Court Opinion

ID: 9900389
Source: CourtListenerOpinion
Date Created: 2023-11-18 22:12:02.995234+00
Date Added: 2024-06-11T09:21:05.100401
License: Public Domain

396                   August 9, 2023               No. 406

         IN THE COURT OF APPEALS OF THE
                 STATE OF OREGON

           In the Matter of the Compensation of
             Maurice Stadeli, DCD, Claimant.

                   CITY OF SALEM,
                        Petitioner,
                             v.
              Maurice STADELI, Deceased,
                       Respondent.
              Workers’ Compensation Board
                   2000008; A177746

  Argued and submitted April 20, 2023.
   Rebecca A. Watkins argued the cause for petitioner. Also
on the briefs were Jaime M. Carlton and SBH Legal.
   Nelson Robert Hall argued the cause for respondent. Also
on the brief was Bennett Hartman, LLP.
   Before Aoyagi, Presiding Judge, and Joyce, Judge, and
Jacquot, Judge.
  JOYCE, J.
  Affirmed.
Cite as 327 Or App 396 (2023)                                           397

          JOYCE, J.
         After working as a firefighter paramedic for
employer City of Salem for many years, claimant Maurice
Stadeli was diagnosed with tonsillar cancer. He under-
went treatment but died about six months later. This case
requires us to assess whether the Workers’ Compensation
Board (“board”) properly construed and permissibly applied
the so-called “firefighters’ presumption” when it reversed
employer’s denial of claimant’s occupational disease claim.
Under that presumption, when a firefighter contracts a
specified disease, including cancer of the throat and mouth
(and meets other criteria, undisputed here), the firefighter
need not satisfy the usual occupational disease standard:
that work was the major contributing cause of the disease.
ORS 656.802(2)(a). Instead, the disease is an occupational
disease presumed to be caused by the firefighter’s employ-
ment. ORS 656.802(4), (5). As applicable here, the employer
may rebut the presumption—and may deny a claim for a
condition or health impairment caused by the disease—
only “on the basis of clear and convincing medical evidence
that the condition or impairment was not caused or contrib-
uted to in material part by the firefighter’s employment.”
ORS 656.802(5)(b).1
         We state the facts supported by substantial evi-
dence consistently with the board’s order. ORS 656.298(7);
ORS 183.482(8)(c). Claimant worked as a firefighter for over
25 years. He also chewed tobacco for “many years.” In 2018,
a biopsy of claimant’s right tonsil revealed an invasive squa-
mous cell carcinoma that was positive for the human papil-
lomavirus 16 (HPV-16).
         All four physician experts who offered evidence in
this case agreed that HPV is a cause of tonsillar cancer
generally, and all three who evaluated claimant’s situation
agreed that HPV was a probable cause of claimant’s cancer
specifically. The three experts on whom the board relied in
reaching its decision—Drs. Pierce, Orwoll, and Beer—also

    1
      As we discuss below, 327 Or App at 405-07, a slightly different standard
applies to employers attempting to rebut the presumption for another group of
diseases. ORS 656.802(4)(a).
398                                      City of Salem v. Stadeli

agreed that HPV was the most significant probable cause of
claimant’s cancer.
         Those experts were also asked about the probability
that either claimant’s habit of chewing tobacco or his work
as a firefighter were causally connected to his cancer. As to
both, no expert was able to cite studies in medical litera-
ture supporting a connection between either tobacco or fire-
fighting and tonsillar cancer, but neither were they able to
definitively state that either had no connection to claimant’s
cancer.
          Pierce, Orwoll, and Beer all had varying opinions
regarding whether tobacco contributed to claimant’s cancer:
(1) Pierce viewed it as a “probable” or “possibly minor” cause.
Although he admitted that the medical literature tended to
support a connection only to front-of-mouth cancers, none-
theless “it’s not good to have carcinogens in your mouth.
You’re going to swallow them past your base of tongue and
tonsil.” (2) Orwoll could not “disagree that [claimant’s] use
of smokeless tobacco might have contributed to his cancer[.]”
She found “ample” data to connect smoking and non-HPV
oropharyngeal cancer, as well as data connecting snuff with
head and neck cancer. “Data in reference to chewing tobacco
for a posterior pharynx cancer are not readily available. I
have been able to determine nothing which would suggest
that there was a significant causal relationship in this
claimant’s case.” (3) Beer concluded that “tobacco use [was]
not a clear contributor in [claimant’s] case.” He noted:
   “Tobacco use is a well-recognized risk factor for oropharyn-
   geal cancer in general. The strongest and most extensive
   evidence supports a strong relationship between smoking
   and oropharyngeal cancer. The risk for smokers is as high
   as 10-fold higher than in non-smokers. The data for chew-
   ing tobacco is less extensive. Chewing tobacco is a risk fac-
   tor for oral cancers overall, but most of the impact appears
   to be on cancers of the front of the mouth (lips, che[e]ks, and
   gums). The impact of chewing tobacco products on tonsillar
   cancer is not as well established and is certainly smaller
   than smoking.”
        Pierce, Orwoll, and Beer also had slightly vary-
ing opinions regarding whether firefighting contributed to
Cite as 327 Or App 396 (2023)                            399

claimant’s cancer: (1) Although Pierce acknowledged that
firefighting “can’t be excluded” as contributing to claim-
ant’s cancer, “the way we understand it[,] it’s not thought
to” materially contribute. He noted that a number of stud-
ies show correlations between carcinogen exposure that can
occur with firefighting and “certain types of cancer”—such
as lymphoma, mesothelioma, and kidney cancer, as well as
“laryngeal cancers but not other head and neck cancers”—
but no study addressed tonsillar cancer: “[I]t’s really hard
to find anything specific on tonsillar cancer in firefighting.
I couldn’t find it, actually.” When asked whether certain
“known or probable human carcinogens” to which firefight-
ers are exposed play a “contributing role” in tonsillar can-
cer, Pierce responded: “Any known human carcinogen would
have the potential to contribute to any individual’s develop-
ment of cancer. * * * [C]ertainly no one would argue that any
of the known carcinogens couldn’t contribute to the develop-
ment of cancer.”
         (2) Orwoll believed that it was “extremely unlikely
that [claimant’s] occupational exposure materially contrib-
uted to cause his cancer.” Similar to Pierce, Orwoll acknowl-
edged that “[o]ne could certainly never say that there is
absolutely no chance that any [of claimant’s firefighting
activities] could have any effect whatsoever on cancer devel-
opment.” In Orwoll’s view, the medical literature shows
“inconsistent and inconstant association” between firefight-
ing and all types of head and neck cancer, and found “no
reliable medical evidence that paramedic/firefighting activ-
ities create an elevated risk for tonsillar cancer[.]”
         (3) Beer concluded that, “to a reasonable degree
of medical probability, [claimant’s] work as a paramedic/
firefighter was not a fact of consequence in causing or con-
tributing to his cancer.” Like Pierce and Orwoll, in the con-
text of his opinion regarding the lack of connection between
firefighting and tonsillar cancer, Beer acknowledged that
“it is never possible in medicine to reach 100% confidence
with regard to causation of cancer” and admitted that “no
specific test or marker * * * can prove that [claimant’s] work
as a firefighter didn’t contribute to his tonsillar cancer in
some minor way.” However, Beer observed that “[n]umer-
ous studies have examined potential relationships between
400                                      City of Salem v. Stadeli

firefighting and cancer risk.” Existing research inconclu-
sively “posits that firefighters may have an increased risk
of certain types of cancer due to carcinogen exposure” but
that research “does not demonstrate an increase in risk of
oropharyngeal cancer or specifically tonsillar cancer among
firefighters.”
        Notably, the experts differed in their opinions about
whether HPV alone caused claimant’s cancer. Pierce main-
tained that HPV alone was insufficient, identified tobacco
as the most likely cofactor in claimant’s case, but admitted
that anything else could be a cofactor. By contrast, Orwoll
and Beer were of the view that HPV was the sole cause of
claimant’s cancer.
         As noted above, in Pierce’s opinion, claimant’s can-
cer was likely caused by HPV and tobacco use. He further
opined that HPV alone was insufficient to cause tonsillar
cancer. He specifically explained that HPV infection is com-
mon, while throat cancer is not. “HPV is a very important
[factor in tonsillar cancer], but there are other factors, cer-
tainly.” Given the state of current medical science, Pierce
indicated that it is (1) uncertain or “all to be worked out”
what those other factors are, which could include other car-
cinogens or the biology of the host, and (2) impossible to
exclude anything as a possible contributing cause:
   “we know that having HPV increases your risk of getting
   tonsillar or base of tongue cancer by 1,400 percent. But for
   a given patient sitting in front of us, with all their genetics
   and individual exposures, there’s no way for us to exclude
   anything, to be honest. Nothing. No way ever.”
         Orwoll concluded that claimant’s cancer “was caused
by the HPV virus * * *, which is known to be the cause of
this sort of cancer.” Her opinions reiterate several times that
HPV was “the” cause of claimant’s cancer. Orwoll was not
asked about, nor did she address, Pierce’s theory that the
low rate of tonsillar cancer among the HPV-infected implies
that other cofactors must be at play.
        In his initial opinion, Beer stated that HPV “alone
was the most likely cause.” When Beer was asked to respond
to Pierce’s testimony that “medical science is incapable of
excluding all possible causes of cancer, particularly in the
Cite as 327 Or App 396 (2023)                                  401

case of an individual patient,” Beer agreed with Pierce’s
statement. As to the point that few HPV infected people
develop cancer, Beer agreed:
            “Claimant’s counsel has tried to minimize the
   likely impact of HPV, pointing out that not everyone who
   has HPV goes on to develop cancer. It is true that not
   everyone who has HPV will develop cancer. Likewise, not
   everyone who smokes develops lung cancer; not every life-
   guard unwilling to lather themselves in sunscreen will
   develop skin cancer; nor will every person who has worked
   with asbestos develop mesothelioma. However, scientific
   research informs that tobacco use does cause lung, mouth
   and throat cancer; sun exposure does cause skin cancer;
   and exposure to certain chemicals, like asbestos does cause
   mesothelioma. The same is true of HPV and weighing the
   totality of the facts, it is the most probable explanation for
   [claimant’s] cancer.”
Beer stood by his view that claimant’s “cancer likely resulted
from his underlying HPV.”
         A fourth physician, Holland, also provided evidence,
which we summarize separately because the board did not
rely on it. Unlike the other experts, Holland did not exam-
ine claimant or his records. His evidence consisted of an
opinion he had provided regarding another firefighter, Matt
Laas, who also contracted tonsillar cancer, and a letter in
which he agreed that his analysis, opinions, and conclusions
in the Lass matter also applied to claimant’s matter. Like
the other physicians, Holland agreed that tonsillar cancer
is associated with HPV; he opined that HPV had “played
a causative role in the development of Mr. Laas’ tonsil can-
cer.” In Holland’s view, “[o]ther carcinogens almost certainly
play a role in the development of HPV-associated squamous
cell carcinoma.” In particular, he cited studies supporting
a causal connection between smoking and the development
of cancer in HPV-positive individuals. As to firefighting,
Holland stated:

           “I am not an expert on the carcinogens that fire-
   fighters are exposed to in their work. Still, ORS 656.802
   acknowledges that firefighters with at least five years
   employment have an increased risk of cancer of the throat.
402                                    City of Salem v. Stadeli

   Just as tobacco smoke has been shown to play a role in
   the carcinogenesis of a distinct form of HPV-associated
   oropharyngeal cancer, I believe that the carcinogens that
   Mr. Laas has been exposed to as a firefighter likely played
   a role in the development of his tonsil cancer.”

        The administrative law judge (ALJ) weighed all the
evidence, including the opinions of all four physicians, and
the presumption itself, and found that the evidence “pre-
ponderates in the employer’s favor because there is clear
and convincing medical evidence from Drs. Beer, Orwoll,
and Pierce that claimant’s squamous cell carcinoma of
the right tonsil was not caused or contributed to in mate-
rial part by claimant’s employment.” Accordingly, the ALJ
upheld employer’s denial of claimant’s occupational disease
claim.
         On review, the board reversed the ALJ’s order and
set aside employer’s denial of claimant’s occupational dis-
ease claim. As explained in more detail below, the board was
“not persuaded that [the opinions of Drs. Pierce, Orwoll, and
Beer] establish by clear and convincing medical evidence
that the decedent’s cancer was not caused or contributed to
in material part by his employment.”
         On judicial review, the parties’ arguments center on
whether the board permissibly determined that employer had
not rebutted the presumption. Although the parties and the
board generally agreed about the standard the board should
apply in evaluating whether employers have rebutted the
firefighters’ presumption, construing ORS 656.802(5)(b)—
the standard for rebutting the presumption that applies
here—is an issue of first impression. For that reason, we
address the parameters of the standard before turning to
the board’s decision.
            I. THE APPLICABLE STANDARD
        We first consider whether the board correctly con-
strued the standard for rebutting the firefighters’ pre-
sumption in ORS 656.802(5)(b). We review the board’s
interpretation of statutes for errors of law. ORS 656.298(7);
ORS 183.482(8)(a).
Cite as 327 Or App 396 (2023)                                                403

          The firefighters’ presumption is set out in
two subsections of the occupational disease statute,
ORS 656.802(4) and (5).2 The subsections share certain sim-
ilarities: they afford the firefighters’ presumption (1) to fire-
fighters with five or more years of employment (2) when death,
disability, or impairment is from a specified disease. Neither
of those two facets of the statutory scheme is disputed in this
case. The subsections differ in several ways, two of which are
germane to our analysis: the specified diseases and the stan-
dards for rebutting the presumption. We briefly describe the
two subsections, highlighting those two differences.
        ORS 656.802(4), enacted in 1961, specifies “any
disease of the lungs or respiratory tract, hypertension or
cardiovascular-renal disease.” Or Laws 1961, ch 583, § 1.
As the Supreme Court has observed, “[p]roponents of the

   2
     ORS 656.802 provides, in part:
        “(4)(a) Death, disability or impairment of health of firefighters of any
   political division who have completed five or more years of employment as
   firefighters, caused by any disease of the lungs or respiratory tract, hyperten-
   sion or cardiovascular-renal disease, and resulting from their employment
   as firefighters is an ‘occupational disease.’ Any condition or impairment of
   health arising under this subsection shall be presumed to result from a fire-
   fighter’s employment. However, any such firefighter must have taken a phys-
   ical examination upon becoming a firefighter, or subsequently thereto, which
   failed to reveal any evidence of such condition or impairment of health which
   preexisted employment. Denial of a claim for any condition or impairment
   of health arising under this subsection must be on the basis of clear and
   convincing medical evidence that the cause of the condition or impairment is
   unrelated to the firefighter’s employment.
        “* * * * *
        “(5)(a) Death, disability or impairment of health of a nonvolunteer fire-
   fighter employed by a political division or subdivision who has completed five
   or more years of employment as a nonvolunteer firefighter is an occupational
   disease if the death, disability or impairment of health:
        “(A) Is caused by brain cancer, colon cancer, stomach cancer, testicular
   cancer, prostate cancer, multiple myeloma, non-Hodgkin’s lymphoma, cancer
   of the throat or mouth, rectal cancer, breast cancer [or] leukemia * * *;
        “(B) Results from the firefighter’s employment as a nonvolunteer fire-
   fighter; and
        “(C) Is first diagnosed by a physician after July 1, 2009.
        “(b) Any condition or impairment of health arising under this subsection
   is presumed to result from the firefighter’s employment. Denial of a claim for
   any condition or impairment of health arising under this subsection must
   be on the basis of clear and convincing medical evidence that the condition
   or impairment was not caused or contributed to in material part by the fire-
   fighter’s employment.”
404                                             City of Salem v. Stadeli

bill explained that, according to statistical studies, fire-
fighters are more likely than other occupations to develop
heart and lung diseases, due to smoke and gas exposure in
strenuous conditions, and that firefighters should not bear
the burden of demonstrating that a disease or condition
was caused by firefighting.” SAIF v. Thompson, 360 Or 155,
158, 379 P3d 494 (2016) (citing Minutes, Senate Labor and
Industries Committee, HB 1018, Mar 8, 1961). Although
the presumption was always “disputable,” the legislature
amended the provision several times to clarify the scope of
both the presumption and the standard for rebutting it. See
Thompson, 360 Or at 158-60. Under the current version of
ORS 656.802(4):
   “if the claimant prove[s] certain predicate facts, it [is] pre-
   sumed that the claimant’s condition resulted from * * *
   employment as a firefighter. Employers [may] deny a claim
   only ‘on the basis of clear and convincing medical evidence
   that the cause of the condition or impairment is unrelated to
   the firefighter’s employment.’ ”
Thompson, 360 Or at 160 (emphasis added; citation and
some internal punctuation omitted).
         ORS 656.802(5), enacted in 2009, specifies a differ-
ent, longer list of diseases and, as pertinent here, includes
“cancer of the throat or mouth.” Or Laws 2009, ch 24, § 1;
ORS 656.802(5)(a)(A). The standard for rebutting the fire-
fighter’s presumption is also worded slightly differently:
   “Denial of a claim for any condition or impairment of
   health arising under this subsection must be on the basis
   of clear and convincing medical evidence that the condition
   or impairment was not caused or contributed to in material
   part by the firefighter’s employment.”
ORS 656.802(5)(b) (emphasis added).
       The board and the parties concur that the phrase
“in material part” in ORS 656.802(5)(b) should have the
same meaning as the identical phrase in ORS 656.245(1)(a).3
   3
     ORS 656.245(1)(a) provides:
        “For every compensable injury, the insurer or the self-insured employer
   shall cause to be provided medical services for conditions caused in material
   part by the injury for such period as the nature of the injury or the process
   of the recovery requires, subject to the limitations in ORS 656.225, including
Cite as 327 Or App 396 (2023)                                             405

In Mize v. Comcast Corp-AT & T Broadband, 208 Or App
563, 569-70, 145 P3d 315 (2006), we concluded that “the
words ‘in material part’ [in ORS 656.245(1)(a)] refer to a fact
of ‘consequence’ ” and explained that “any contribution by a
work-related injury to a claimant’s current condition could
be a ‘material’ factor * * * without regard to the amount of
its contribution so long as the injury is a fact of consequence
regarding the claimant’s condition.” (Emphasis in original;
footnote omitted). We applied standard methods of statutory
construction to reach that construction. Nothing we con-
sulted in that interpretational endeavor has since changed:
the statutory and dictionary definitions remain the same,
as do the related statutes within ORS Chapter 656. See id.
at 569-70. Notably, in Mize, we were construing a phrase
within the same statutory scheme as the statute at issue
here. And, as we noted in Mize, “[i]f the same term is used
throughout a statutory scheme, it is presumed that the leg-
islature intended the term to have the same meaning.” Id.
at 569.
         We perceive no reason to construe “in material
part” differently now in ORS 656.802(5)(b) than we did in
Mize in ORS 656.245(1)(a). Therefore, in ORS 656.802(5)(b),
“in material part” refers to a fact of consequence, without
regard to the amount of causation or contribution beyond
being a fact of consequence. For that reason, rebutting the
firefighter’s presumption under ORS 656.802(5)(a) requires
clear and convincing medical evidence that the firefighter’s
employment was not a fact of consequence of any amount in
causing or contributing to a claimant’s condition or impair-
ment. The board correctly construed “in material part” in
ORS 656.802(5)(b) to refer to a “fact of consequence.”
               II. THE BOARD’S DECISION
         We next consider whether the board permissi-
bly applied the standard in ORS 656.802(5)(b) in deciding
that employer failed to rebut the presumption in this case.
Critically, our review of the board’s action in that regard is
   such medical services as may be required after a determination of permanent
   disability. In addition, for consequential and combined conditions described
   in ORS 656.005(7), the insurer or the self-insured employer shall cause to be
   provided only those medical services directed to medical conditions caused in
   major part by the injury.”
406                                   City of Salem v. Stadeli

limited to assessing whether the board reasonably found, on
the evidence before it, that employer had failed to satisfy its
burden of persuasion. Thompson, 360 Or at 157-58. Because
the answer turns on our standard of review as illuminated
by the Supreme Court in Thompson in connection with the
original firefighters’ presumption provision, ORS 656.802(4),
we begin by reviewing that opinion and explaining how it
applies in this case, which involves the later-enacted ORS
656.802(5).
         First, Thompson instructs that, once a claimant
establishes predicate facts, the employer must meet both
the burden of production and the burden of persuasion to
rebut the presumption. In Thompson, the Supreme Court
explained that, since the legislature added the phrase “on
the basis of clear and convincing medical evidence” to the
standard for rebutting the firefighters’ presumption in
ORS 656.802(4)(a), once a claimant proves the predicate
facts, both the burden of production and persuasion shift
to the employer. 360 Or at 160-61. ORS 656.802(5)(b) also
employs the phrase “on the basis of clear and convincing
medical evidence.” Accordingly, once claimant in this case
proved the predicate facts to support the presumption, which
no one disputes, then both the burden of production and the
burden of persuasion shifted to employer.
          Second, Thompson makes clear that, even if an
employer meets its burden of production, the board may
evaluate the evidence favoring the employer and reasonably
find it lacking in persuasive value—that is, an employer may
meet its burden of production and yet fail to meet its bur-
den of persuasion. See Thompson, 360 Or at 166, 169. As we
explain below, the board in this case evaluated the evidence
favoring employer and permissibly found that employer had
not met its burden of persuasion.
         In Thompson, the claimant firefighter suffered a
heart attack caused by atherosclerosis (a blocked artery due
to coronary artery disease). 360 Or at 161. It was undis-
puted, as here, that the claimant had proved the predicate
facts to give rise to the firefighters’ presumption. Id. at 157,
162. The claimant offered no medical evidence to prove that
his work caused his atherosclerosis; he relied entirely on the
Cite as 327 Or App 396 (2023)                                 407

firefighters’ presumption. Id. at 162. To attempt to rebut
the presumption, SAIF offered evidence from Dr. Semler,
who had examined the claimant and reviewed his medical
records. Id. at 162-64.
         Responding to the ultimate question that he under-
stood that SAIF had asked him to address, Semler con-
cluded that “it is highly probable that [claimant’s] work as a
firefighter is not the major contributing cause of his cardiac
condition.” Thompson, 360 Or at 162 (brackets in original;
internal quotation marks omitted). As the Supreme Court
explained, Semler’s evidence “reduced to three propositions”:
(1) The causes of atherosclerosis are unknown; (2) the claim-
ant exhibited none of the known risk factors for atheroscle-
rosis; and (3) atherosclerosis is unrelated to firefighting (a
conclusion Semler based on the dearth of medical literature
linking firefighting to atherosclerosis). Id. at 163-64, 167-68.
       In concluding that SAIF had not rebutted the pre-
sumption, the board reasoned:
       “ ‘We are not persuaded * * * that Dr. Semler’s opinion
   satisfies SAIF’s ‘clear and convincing’ burden to overcome
   the statutory presumption. Dr. Semler conceded that the
   cause of atherosclerosis is unknown. Despite that conces-
   sion, Dr. Semler ruled out any contribution from claimant’s
   employment as a firefighter. Dr. Semler did not persua-
   sively explain, however, how he was able to make such a
   categorical exclusion, given that the causes of that condi-
   tion were unknown. The lack of such a persuasive explana-
   tion is particularly significant, given that the record does
   not establish that claimant had any identified ‘risk factors’
   for atherosclerosis.’ ”
Thompson, 360 Or at 164.
         On judicial review, this court reversed the board’s
order. SAIF v. Thompson, 267 Or App 356, 340 P3d 163
(2014), rev’d, 360 Or 155, 379 P3d 494 (2016). The Supreme
Court accepted review, reversed our decision, and affirmed
the board’s order. Thompson, 360 Or at 157-58.
        The Supreme Court observed that the board had
done “what ORS 656.802(4) directed it to do once claimant
established, by means of the firefighters’ presumption, that
408                                      City of Salem v. Stadeli

his atherosclerosis ‘result[ed]’ from his employment as a fire-
fighter: The board asked whether SAIF had persuaded it by
clear and convincing medical evidence that claimant’s ath-
erosclerosis was ‘unrelated’ to his employment.” Thompson,
360 Or at 166 (brackets in original). And, in the end, “the
board reasonably could (and did) find that Semler’s report
and his testimony were not persuasive[.]” Id. at 167.
         The steps the court took to reach that conclusion
inform our analysis here, and so we review each step and
apply it to this case in turn, beginning with the standard
that the experts were asked to address and moving through
the evidence the experts proffered. Our goal is to discern
whether the evidence was such that the board could rea-
sonably be unpersuaded that firefighting was not a fact of
consequence of any amount in causing or contributing to
claimant’s cancer.
         To begin, we quote the board’s reasoning in this
case:
       “Dr. Pierce’s opinion does not support the employer’s bur-
   den. Specifically, he opined that although HPV-16 was an
   important contributor to the decedent’s cancer, other con-
   tributors, including firefighting, could not be ruled out. He
   explained that HPV alone is not sufficient to cause cancer,
   but that something in addition to HPV contributed to the
   decedent’s cancer. Under such circumstances, Dr. Pierce’s
   opinion does not support a conclusion, on a ‘clear and con-
   vincing’ basis, that the decedent’s cancer was not caused
   or contributed to in material part by his employment. See
   656.802(5)(b).
       “Further, we are unpersuaded by the opinions of Drs.
   Orwoll and Beer. Although these physicians opined that
   HPV was the most likely cause of the decedent’s cancer, they
   did not persuasively explain how that conclusion ruled out
   firefighting as a fact of consequence. In light of Dr. Pierce’s
   opinion that something in addition to HPV contributed to
   the decedent’s cancer, the opinions of Drs. Orwoll and Beer
   are conclusory and not well explained.
      “Moreover, Dr. Orwoll’s and Dr. Beer’s opinions are
   internally inconsistent. Specifically, Dr. Orwoll stated that
   the medical literature regarding firefighting and tonsillar
   cancer was inconclusive; yet, she affirmatively eliminated
Cite as 327 Or App 396 (2023)                                 409

   firefighting as a fact of consequence in the decedent’s case.
   In addition, Dr. Orwoll stated that although HPV was ‘the
   presumed cause’ and she did not know of any data correlat-
   ing oropharynx cancer and chewing tobacco, she could not
   rule out the decedent’s tobacco use as a contributing factor.
   However, in contrast to her tobacco conclusion, Dr. Orwoll
   eliminated firefighting as a fact of consequence based on
   those very same factors (i.e., because HPV was the most
   likely cause and the medical literature regarding firefight-
   ing and head and neck cancer was inconclusive).
      “Similarly, Dr. Beer stated that there was no test to
   prove that the decedent’s employment did not contribute to
   his tonsillar cancer in some minor way. Yet, he eliminated
   the decedent’s firefighting as fact of consequence, which, as
   set forth above, includes even a ‘minor cause.’ [S]ee Mize,
   208 Or App at 571.
      “Without further explanation for the foregoing inconsis-
   tencies, we are unpersuaded by the opinions of Drs. Orwoll
   and Beer on a ‘clear and convincing’ standard.”
(Emphasis in original; some citations omitted.)
         The first proposition that the Supreme Court dis-
cussed in Thompson was Semler’s testimony that the causes
of atherosclerosis are unknown. 360 Or at 167-68. The court
observed that the board was entitled to find that that testi-
mony provided no persuasive evidence that claimant’s con-
dition was unrelated to the claimant’s employment. Id. That
kind of testimony is merely a “confession of an inability to
identify a cause” of a claimant’s condition, “rather than evi-
dence that [the] claimant’s condition or impairment is unre-
lated to” employment. Id. at 168 (brackets and emphasis in
original; internal quotation marks omitted).
         Here, unlike in Thompson, all three physicians
agreed that one cause of tonsillar cancer is known: HPV
infection. Their opinions diverged, however, as to whether it
is known that HPV alone can cause tonsillar cancer. Even
assuming that both Orwoll and Beer were of the view that
HPV alone could cause tonsillar cancer, each also acknowl-
edged that other causes could not be excluded. Moreover,
Pierce testified that HPV alone was insufficient to cause
tonsillar cancer, pointing to the fact that few HPV-infected
individuals go on to develop tonsillar cancer, and that the
410                                            City of Salem v. Stadeli

exact nature of possible cofactors is presently unknown.
Beer responded to Pierce’s testimony by emphasizing that
HPV is definitively linked to tonsillar cancer. However clear
that link is, that clarity does not bear on whether other
causes exist. The board reasonably could have found itself
more persuaded by Pierce’s testimony that something other
than HPV is likely at play in developing tonsillar cancer,
given that the population of the HPV-infected is so much
larger than the population of those with tonsillar cancer.
And it also reasonably could have found that Beer’s remon-
strance, based only on the close connection between HPV
and tonsillar cancer, did not detract from the persuasive-
ness of Pierce’s testimony.
         In Thompson, the Supreme Court next addressed
Semler’s testimony that the claimant had none of the known
risk factors for atherosclerosis. 360 Or at 168. The court
explained that that testimony only ruled out the known risk
factors, it did not bear on the possibility that the claimant’s
work was a cause of his condition, and so the board reason-
ably could have ascribed no persuasive value to that evi-
dence. Id.
         Here, the evidence was unanimous that claimant
had the primary known risk factor for tonsillar cancer:
HPV. As to whether other risk factors were known, the
experts agreed that being male and over 40, claimant was
in the demographic group that is most likely to develop ton-
sillar cancer. As to tobacco use and firefighting, the experts
were generally consistent: No compelling evidence of causal
connection currently exists between either tobacco use or
firefighting and the particular kind of cancer claimant suf-
fered from; however, neither can be excluded as a possible
cause of tonsillar cancer. The board was entitled to find that
that level of uncertainty did not persuade it that claimant’s
employment was not a fact of consequence in causing or con-
tributing to his condition.4
        Finally, in Thompson, the Supreme Court addressed
Semler’s opinion that the claimant’s atherosclerosis was
unrelated to firefighting, based on his inability to find in
   4
     See also Thompson, 360 Or at 163 n 6 (observing that the board could rea-
sonably find equivocal testimony about causation unpersuasive).
Cite as 327 Or App 396 (2023)                                 411

the medical literature a proven connection between fire-
fighting and atherosclerosis. Thompson, 360 Or at 168. The
board had observed that Semler had also testified that the
causes of atherosclerosis are unknown, and that the claim-
ant had no known risk factors for atherosclerosis. Id. In
light of that other testimony, the board found that the basis
for Semler’s opinion that the claimant’s atherosclerosis was
unrelated to firefighting was not apparent and accordingly
not sufficiently persuasive to meet SAIF’s burden of persua-
sion. Id. In the eyes of the Supreme Court, the board acted
permissibly:
   “As we read the board’s opinion, the board evaluated the
   persuasive value of Semler’s opinion and found it lacking.
   As the board explained, Semler’s opinion that atherosclero-
   sis is unrelated to firefighting was at odds with his testi-
   mony that the causes of atherosclerosis are unknown. The
   latter testimony undercut the former, or so the board rea-
   sonably could find.”
Id. at 169.
        Here, the experts similarly and unanimously
reported that no medical literature showed an association
between firefighting and tonsillar cancer, and that lack of
empirical data led each to give the opinion that firefighting
was unlikely to have been materially related to causing or
contributing to claimant’s condition.
         As to Pierce’s opinion, the board reasoned that it did
“not support a conclusion * * * that [claimant’s] cancer was
not caused or contributed to in material part by his employ-
ment.” To the extent that Pierce also responded that it was
“completely unknown” whether there were no other contrib-
utors other than HPV to claimant’s cancer, the board was
entitled to weigh that evidence against employer’s burden.
          As to Orwoll’s and Beer’s opinions, the board
explained that they were unpersuasive for several reasons.
Again, the board was entitled to find those opinions unper-
suasive. One reason the board gave was that Orwoll and
Beer “did not persuasively explain how [the strong link
between HPV and tonsillar cancer] ruled out firefighting as
a fact of consequence.” To the extent that Orwoll and Pierce
gave opinions that firefighting was unlikely to be a fact of
412                                  City of Salem v. Stadeli

consequence in causing or contributing to claimant’s con-
dition, the board could reasonably see the opinions as not
establishing that it was highly probable that firefighting
was not a fact of consequence.
         The board gave two other reasons for finding the
opinions of Orwoll and Beer to be unpersuasive. First, the
board observed that “[i]n light of Dr. Pierce’s opinion that
something in addition to HPV contributed to [claimant’s]
cancer, the opinions of Drs. Orwoll and Beer are conclusory
and not well explained.” On this record, the board could rea-
sonably find Pierce’s opinion more persuasive—that is, the
board could find compelling Pierce’s reasoning that it was
likely that other factors contribute to tonsillar cancer, given
that so few HPV-infected persons develop cancer—and that
Orwoll’s and Beer’s opinions did not undercut the persua-
sive value of Pierce’s opinion. But the primary reason that
the board was entitled to find persuasive the testimony of
all three of the experts is that all the opinions indicate that
the state of medical science is presently uncertain as to the
causation of tonsillar cancer, not that Orwoll and Pierce
were overly confident that science is certain in eliminating
firefighting as a cause.
         For the above reasons, (1) the board did not err as
a matter of law in construing the standard to rebut the
firefighters’ presumption in ORS 656.802(5)(b), and (2) the
board permissibly could find that the record did not meet
employer’s burden of persuasion under that standard.
        Affirmed.