Shinshu Med J, 70⑶：157～167, 2022

Follow-up System for Childhood Cancer Survivors
Via Germline Clinical Sequencing
Tatsuo Watanabe1）, Koichi Hirabayashi1）＊, Daisuke Morita1）2）
Tomomi Yamaguchi3）4）5）, Eri Okura1）, Hirokazu Morokawa1）
Shoji Saito1）, Miyuki Tanaka1）, Yozo Nakazawa1） and Tomoki Kosho3）4）5）6）1） Department of Pediatrics, Shinshu University School of Medicine
2） Institute for Biomedical Sciences, Shinshu University Interdisciplinary Cluster for Cutting Edge Research3） Department of Medical Genetics, Shinshu University School of Medicine
4） Center for Medical Genetics, Shinshu University Hospital5） Research Center for Supports to Advanced Science, Shinshu University
6） Division of Clinical Sequencing, Shinshu University School of Medicine

Background : A second malignant neoplasm (SMN) has the greatest impact on the prognosis of childhood cancer
survivors (CCSs). Although germline abnormalities in cancer predisposition genes have been reported as a causeof SMN in CCSs, the genetic background is not considered for SMN surveillance in the follow-up guidelines.
This study aimed to present an SMN surveillance system for CCSs using germline cancer predisposition genes
and evaluate their efficacy. We also aimed to elucidate the psychological impact of a surveillance system on CCSs
and their guardians.
Methods : CCSs who visited the long-term follow-up clinic at Shinshu University Hospital were recruited. They
underwent next-generation sequencing-based germline genetic investigation using a custom panel including 165
cancer predisposition genes and a multiplex ligation-dependent probe amplification method for TP53. Based on
the molecular findings, appropriate SMN surveillance was proposed. A questionnaire-based survey was conductedto comprehend the thoughts of CCSs and/or their guardians regarding SMN, clinical sequencing, and SMN sur­veillance.
Results : As of March 2021, 16 CCSs, mostly with leukemia as a primary cancer, participated in this study. No
pathogenic or likely pathogenic variants were detected in any of the participants. Variants of uncertain significancewere found in four CCSs showing increased anxiety.
Conclusions : This study could not show the efficacy of an SMN surveillance system for CCSs, because no patho­
genic or likely pathogenic variants were detected. Further evaluation, including more CCSs with a wider spec­
trum of cancers, would be necessary to evaluate this system. Genetic counseling might require careful anticipa­
tory guidance for clinical sequencing and follow-up services. Shinshu Med J 70 : 157―167, 2022
(Received for publication December 24, 2021 ; accepted in revised form January 12, 2022)
Key words : cancer predisposition genes, childhood cancer survivor, clinical sequencing, follow-up system,
second malignant neoplasm

Ⅰ＊

Corresponding author : Koichi Hirabayashi
Department of Pediatrics, Shinshu University School of
Medicine, 3-1-1 Asahi, Matsumoto, Nagano 390-8621, Japan
E-mail : kohira@shinshu-u.ac.jp

No. 3, 2022

Introduction

The improvement in the cure rate of pediatric can­cer in recent years has led to an increase in childhood
cancer survivors (CCSs)1）2）. Consequently, late effects
in CCSs have become a serious problem3）. A second
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Watanabe・Hirabayashi・Morita et al.

malignant neoplasm (SMN) has the greatest impact

this study at the LTFU Clinic of the Department of

4）

on long-term life prognosis among the late effects .

Pediatrics in Shinshu University Hospital. Upon agree­

Therefore, early detection and early stage treatment

ing to participate in the study, CCSs and/or theirof CCSs with SMN is very important to improve theirguardians were referred to the Center for Medical

long-term life prognosis5）.

Genetics for genetic counseling for clinical sequenc­

Anticancer drugs and/or radiation therapy areing provided by a clinical geneticist (TK), a pediatricwell-known causes of SMN. Additionally, germline

oncologist (TW), and certified genetic counselors.

abnormalities in cancer predisposition genes in CCSs

Informed consent was obtained from adult CCSs andhave also been reported as a cause of SMN in recent

guardians of minor CCSs (younger than 20 years old).

6）

years . CCSs have been shown to have a higher prob­

As of March 2021, 16 CCSs participated in the study.

ability of carrying germline abnormalities in cancer

Ｂ

Clinical sequencing

6）7）

.

After obtaining consent from the participantsHence, the assessment of germline abnormalities in

and/or their guardians, 5 mL of peripheral blood wascancer predisposition genes for CCSs could be usefulcollected from CCSs with no history of allogeneic he­for the stratification of the risk for development ofmatopoietic stem cell transplantation (allo-HSCT). In

SMN. However, in the current follow-up guidelines

contrast, both nails and hair were collected from CCSs

for CCSs, the genetic background is considered onlywith a history of allo-HSCT. To extract genomic DNA

in some SMN screening systems, such as breast can­from the samples, QIAcube (Qiagen, Hilden, Germany)cer (BRCA 1/2), and the stratification of SMN risk is

was used for peripheral blood, and ISOHAIR (NIP­8）

mainly based on the history of anticancer therapies .

PON GENE, Tokyo, Japan) was used for nails andTherefore, we introduced a surveillance system

hair. All exons and the flanking sequences of 165

using clinical sequencing of germline cancer predis­

cancer predisposition genes (Table 1) were analyzed

position genes for CCSs to assess the risk of develop­

using a next-generation sequencer, Ion GeneStudioing SMN in a long-term follow-up (LTFU) clinic at

S5 (Thermo Fisher Scientific, Waltham, MA) accord­

Shinshu University Hospital. The purpose of thising to the manufacturer’s protocol. These 165 cancer

study was to present the clinical and molecular find­predisposition genes, selected from literature reviews

ings in CCSs, application of SMN surveillance, andand National Comprehensive Cancer Network (NCCN)

discuss the thoughts of the participants obtained

guidelines, have been reported to cause cancers asso­

through this follow-up system. The study also aimed

ciated with germline abnormalities6）9）-16）.

predisposition genes than the general population

to evaluate the efficacy of the follow-up system.
Ⅱ Methods
Ａ

Participants

Sequencing data were mapped to human genome
hg19 using Torrent Suite software (Thermo Fisher
Scientific), and single nucleotide variants and small
insertions/deletions were detected from the mapped

An outline of this study is presented in Fig. 1. The

data using the Torrent Variant Caller plug-in. De­

participants were CCSs who were recruited from thetected variants were annotated using SnpEff17） and

LTFU clinic at Shinshu University Hospital. The

SnpSift using the processed vcf file of the Genome

LTFU clinic was established in 2014 and included

Aggregation Database (gnomAD) version 2.1.118） andapproximately 140 CCSs as of October 2020, some of

Human Genetic Variation Database version 2.319）.

whom were introduced from other hospitals after theMis­sense variants were analyzed with dbNSFP3.4c,completion of their cancer therapy. This study was

and splice site alterations were analyzed using

approved by the Ethics Committee of Shinshu Uni­

dbscSNV1.1. Integrative Genomics Viewer (Broad Institute,

versity School of Medicine in January 2019 (approval

Cambridge, MA, USA) was used to visualize the read

number : 633) and was initiated in August 2019.

alignments and sequencing errors.

We informed the CCSs and/or their guardians of
158

In addition, copy number variants were analyzed
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CCSs follow-up using clinical sequencing

Fig. 1 Outline of this study
COG, Children’s Oncology Group ;LTFU, long-term follow-up ;SMN, second malignant neoplasm

Table 1

List of 165 cancer predisposition genes analyzed in this study

ABCB11, ACD, ALK, ANKRD26, APC, ATM, AXIN2, BAP1, BLM, BMPR1A, BRAF,
BRCA1, BRCA2, BRIP1, BUB1B, CBL, CDC73, CDH1, CDK4, CDKN1B, CDKN1C,
CDKN2A, CEBPA, CHEK2, COL7A1, CTC1, CYLD, DDB2, DDX41, DICER1, DIS3L2,
DKC1, DOCK8, EGFR, ELANE, EPCAM, ERCC1, ERCC2, ERCC3, ERCC5, ETV6,
EXT1, EXT2, FAH, FANCA, FANCB, FANCC, FANCD2, FANCE, FANCF, FANCG,FANCI, FANCL, FANCM, FANCQ, FANCR, FANCT, FH, FLCN, GATA2, GBA, GFI1,
GJB2, GPC3, GREM1, HAX1, HFE, HMBS, HRAS, IKZF1, ITK, KIT, KRAS, MAP2K1,
MAP2K2, MAX, MEN1, MET, MLH1, MPL, MSH2, MSH3, MSH6, MTAP, MUTYH,
NBN, NF1, NF2, NHP2, NOP10, NRAS, NTHL1, PALB2, PAX5, PDGFRA, PHOX2B,
PMS2, POLD1, POLE, POLH, PRKAR1A, PRSS1, PTCH1, PTEN, PTPN11, RAD51C,
RAD51D, RAF1, RB1, RBBP6, RECQL4, RET, RHBDF2, RMRP, RPL5, RPL11, RPL35A,
RPS10, RPS17, RPS19, RPS24, RPS26, RTEL1, RUNX1, SAMD9, SAMD9L, SBDS,
SDHA, SDHAF2, SDHB, SDHC, SDHD, SERPINA1, SH2B3, SH2D1A, SHOC2,
SLC25A13, SLX4, SMAD4, SMARCA4, SMARCB1, SMARCE1, SOS1, SRY, STAT3,
STK11, SUFU, TERC, TERT, TGFBR1, TINF2, TMEM127, TNFRSF6, TP53, TRIM37,
TSC1, TSC2, UROD, VHL, WAS, WRAP53, WRN, WT1, XPA, XPC
No. 3, 2022

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Watanabe・Hirabayashi・Morita et al.

using the multiplex ligation-dependent probe amplifi­

the two surveys, a paired t-test was performed

cation method for TP53, the most common gene re­using the GraphPad Prism software package (version

lated to leukemia and pediatric cancers, using Ap­

9.2 ; GraphPad Software, San Diego, CA, USA).

plied Biosystems VRTi Dx and Applied Biosystems

Ⅲ Results

3500 Genetic Analyzer (Thermo Fisher Scientific, Wal­
tham, MA), according to the manufacturer’s protocol.

As of March 2021, 37 CCSs were informed of this

Detected variants were assessed through Humanstudy, and 16 of them wished to participate. The clin­

Gene Mutation Database professional 2020.1 (Qiagen)ical and molecular findings of the participants are

20）

and ClinVar . If not registered, they were interpret­

presented in Table 3. Types of childhood cancer in­ed according to the 2015 American College of Medical

cluded acute lymphoblastic leukemia (ALL, n＝9),

Genetics and Genomics or the Association for Molec­

acute myeloid leukemia (AML, n＝2), neuroblastoma

21）

by a clinical geneticist(n＝2), myeloid/NK cell precursor acute leukemia (n(TK), pediatric oncologist (TW), and molecular genet­＝1), juvenile myelomonocytic leukemia (n＝1), andicist (TY). Genetic counseling was provided to CCSs

Wilms tumor (n＝1). The median age of the CCSs

and/or their guardians by presenting the results ofundergoing clinical sequencing was 22 years (range,clinical sequencing and relevant surveillance plans.

15-42 years), six of whom were minors. The male-Ｃ

to-female sex ratio was 1 : 1. Four CCSs had a historyular Pathology guidelines

Surveillance for SMN
When pathogenic or likely pathogenic variantsof SMN. No pathogenic variants corresponding towere detected in TP53, surveillance for SMN was

likely pathogenic or pathogenic variants were detect­5）

proposed according to the Toronto protocol in com­

ed in any of the participants. Twelve variants of un­bination with the guidelines of the Children’s Oncolo­certain significance (VUSs) were detected in 10 par­8）

ticipants. Most VUSs (eight of 12) were missensegy Group (COG) LTFU program .

When pathogenic or likely pathogenic variants inother genes, for which surveillance methods were22）

variants.
Since Patient 1 had four cancers (ALL, rectal can­specified in the NCCN guidelines , American Asso­cer, ovarian cancer, and breast cancer) and a family

ciation for Cancer Research-Childhood Cancer Pre­history of gastric cancer, she was supposed to have adisposition Workshop review articles

23）
-39）

, and/or

germline pathogenic variant of some cancer predis­

GeneReviews , SMN surveillance was proposed ac­

position genes. Contrary to our expectations, only thecording to the COG LTFU guidelines. In contrast,

VUSs of SAMD9L and POLD1 genes were detected.

when pathogenic or likely pathogenic variants wereNo specific SMN surveillance has been proposed todetected in genes for which no guidelines were es­

date. Patient 10 developed three tumors (neuroblas­

tablished, SMN surveillance was proposed based ontoma, cervical cancer, and meningioma), but only aprevious reports in combination with COG LTFU

VUS of the MPL gene was detected. No specific SMN

guidelines.

surveillance has been proposed to date. Patient 13

Ｄdeveloped ALL and meningioma, but no pathogenic

40）

Questionnaire-based survey
To comprehend the thoughts of CCSs and/or theirvariants were detected. In Patient 16, who developed

guardians regarding SMN, clinical sequencing, andAML, a heterozygous variant was detected in the

SMN surveillance, a questionnaire-based survey was

MUTYH gene. The variant was interpreted as aconducted. The questionnaire consisted of six ques­

20）
VUS, according to ClinVar®
, in which the variant

tions, each of which had five choices (strongly dis­

was registered as likely benign in three cases, VUS

agree, disagree a little, neither agree nor disagree,

in five cases, likely pathogenic in three cases, andagree a little, and strongly agree) (Table 2). The same

pathogenic in one case. MUTYH-related polyposis issurvey was conducted before and after clinical sequen­

an autosomal recessive disease associated with ancing. To assess differences in their thoughts between

increased risk of colorectal cancer (CRC) ; however,160

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CCSs follow-up using clinical sequencing
Table 2

The questionnaire used in this study

Q1. Are you worried about your child developing a second malignant neoplasm (SMN) in the future?
Strongly disagree
1

Disagree a little

Neither agree nor disagree

Agree a little

2

3

4

Strongly agree
5Q2. Do you think that this clinical sequencing of cancer predisposition genes is useful for yourself (or your child)?
Strongly disagree
1

Disagree a little

Neither agree nor disagree

Agree a little

2

3

4

Strongly agree
5Q3. Do you want to tell the results of this clinical sequencing of cancer predisposition genes to your family?
Strongly disagree
1

Disagree a little

Neither agree nor disagree

Agree a little

2

3

4

Strongly agree
5Q4. Do you want to receive regular follow-up examinations of late eﬀects (including SMN) in the future?
Strongly disagree
1

Disagree a little

Neither agree nor disagree

Agree a little

2

3

4

Strongly agree
5Q5. Do you want to receive periodic follow-up by a clinical geneticist and/or certiﬁed genetic counselor?
Strongly disagree
1

Disagree a little

Neither agree nor disagree

Agree a little

2

3

4

Strongly agree
5Q6. Do you want to know about late eﬀects apart from the SMN?
Strongly disagree
1

Disagree a little

Neither agree nor disagree

Agree a little

2

3

4

Strongly agree5

the risk of CRC and extraintestinal cancer in individ­

before and after clinical sequencing of the CCSs or

41）

uals with pathogenic variants in MUTYH is unclear .

guardians who participated in this study (Table 2).

Since Patient 16 was treated with anticancer agents

Table 4 summarizes the results of the questionnaire-and underwent allo-HSCT using total body irradia­

based survey. No significant change in scores wastion, he was considered to have a relatively high riskobserved in any of the questions before and afterof SMN. Therefore, we proposed the option of SMN

clinical sequencing. For the first question, which fo­surveillance in this case. No specific or further SMN

cused on anxiety about SMN, the results were un­surveillance was proposed for other patients withchanged before and after clinical sequencing in seven

VUSs.
We also conducted a questionnaire-based survey
No. 3, 2022

CCSs. However, anxiety increased in four CCSs, anddecreased in five CCSs. All four patients with in­
161

162

Shinshu Med J

42

22

27

37

16

24

15

16

19

32

22

34

30

20

16

16

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

M

F

F

M

F

M

F

M

F

F

M

M

M

F

M

F

Sex

AML

ALL

WT

ALL

NB

AML

NB

ALL

JMML

ALL

ALL

ALL

9

3

5

5

6

0

0

14

15

13

13

4

12

10

Myeloid/NK
cell precursor
acute leukemia

ALL

14

15

Age at onset ofprimary disease(years)ALL

ALL

Primary
disease---Meningioma (22)--

Cervical cancer (20)
Meningioma (31)

-

-

-

-

-

-

-

Paternal grandfather : gastric cancer, lung cancer
Maternal grandfather : gastric cancer

Maternal grandfather : lung cancer

-

-

-

-

-

Mother : breast cancer
Paternal grandmother : kidney cancer

-

-

-

-

Paternal grandmother : malignant lymphoma

Maternal grandfather : prostate cancer

Mother : bilateral breast cancer--

Maternal grandfather : cholangiocarcinoma
Maternal grandmother : breast cancer
Maternal grandmother : uterine cancer

-

-

-

-

-

-

P

-

-

Maternal grandmother : cancer

Paternal grandmother : cancer

Maternal grandfather : colorectal cancer

Colorectal polyps(20, 22)-

Father : gastric cancer
Paternal grandfather : gastric cancer

Family history of malignancy

Rectal cancer (30)
Ovarian cancer (30)
Breast cancer (42)Second tumor(age, years)

Clinical and molecular findings in 16 participants

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

LP

MUTYH (NM_001128425.2 : c.934-2A＞G) : splice-site variant

GJB2 (NM_004004.5 : c.508_511dup) : frameshift variant

-

-

-

SAMD9L (NM_152703.3 : c.2357C＞G) : missense variant

MPL (NM_005373.2 : c.853G＞T) : missense and/or splicesite variant

MSH6 (NM_000179.2 : c.3772C＞G) : missense variant-

BRCA1 (NM_007294.3 : c.626C＞T) : missense variant-

CDK4 (NM_000075.3 : c.887A＞G) : missense variant-

POLE (NM_006231.3 : c.76A＞G) : missense variant

ATM (NM_000051.3 : c.323C＞G) : missense variant
BRIP1 (NM_032043.2 : c.2830C＞G) : missense variant

SAMD9L (NM_152703.3 : c.2256G＞A) : missense variant
POLD1 (NM_002691.3 : c.1138-7C＞A) : splice-site variant

VUS

Detected variant(s)ALL, acute lymphoblastic leukemia ; AML, acute myeloid leukemia ; F, female ; JMML, juvenile myelomonocytic leukemia ; LP, likely pathogenic ; M, male ; NK, natural killer ; P, pathogenic ; VUS, variant of
uncertain significant ; WT, Wilms tumor

Age at clinicalsequencing(years)Patient
no.

Table 3

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CCSs follow-up using clinical sequencing
Table 4 Responses of childhood cancer survivors or their guardians to the questionnaires regarding anovel follow-up system
Q1

Q2

Q3

Q4

Q5

Q6

Patient
no.

Pre

Post

Pre

Post

Pre

Post

Pre

Post

Pre

Post

Pre

Post

1

5

5

5

5

4

4

5

5

5

5

5

5

2

2

2

5

5

5

5

5

5

5

5

4

5

3

3

4

5

4

4

5

5

5

4

5

5

5

4

5

4

4

5

5

5

5

5

4

5

4

4

5

4

5

5

5

5

5

4

4

3

4

4

4

6

4

4

5

5

4

4

5

5

3

3

4

4

7

1

1

5

5

5

5

5

5

5

5

5

4

8

4

2

5

5

5

5

5

5

5

4

5

5

9

3

4

5

5

4

5

4

5

4

5

4

4

10

5

3

5

5

5

5

5

5

5

5

5

5

11

3

4

4

5

4

4

4

5

4

4

4

4

12

4

3

4

4

4

4

4

4

2

4

4

4

13

5

3

5

4

5

5

5

5

5

5

5

5

14

2

2

4

4

4

4

5

5

3

3

4

4

15

4

4

4

4

4

4

4

4

4

3

4

4

16

4

4

5

5

5

5

5

5

3

3

4

4

Mean
p-value

3.6

3.4

4.7

4.7

4.5

4.6

4.7

4.8

4.0

4.3

4.4

0.362

1.000

0.164

creased anxiety were CCSs who were found to have

0.164

0.216

4.4
1.000

No pathogenic or likely pathogenic variants in the
165 germline cancer predisposition genes were de­

VUS.
Ⅳ Discussion

tected in this study. The prevalence of pathogenic
variants ranged from 5.8 ％ to 11.5 ％6）42）43）according

In this study, we described the preliminary data of

to previous reports on germline abnormalities in can­an originally established SMN surveillance systemcer predisposition genes in CCSs. Possible causes forfor CCSs, considering the results of clinical sequenc­

detecting no pathogenic or likely pathogenic variants

ing for germline cancer predisposition genes. The

in this study are estimated as follows : First, thepurpose of this system is to detect SMNs in CCSs at

number of CCSs who underwent clinical sequencing

an early stage and consequently improve their long-

was small. Second, the types of primary cancer were

term prognosis. A distinctive feature of this systembiased, as 13 of 16 participants in the current study

is the introduction of a germline genetic investiga­

developed acute leukemias as primary cancer ; CCSs

tion, as a clinical basis, into a previously established

who had Li-Fraumeni syndrome-related solid tu­

LTFU clinic in the Department of Pediatrics in ourmors (e.g., adrenocortical cancer, osteosarcoma, rhab­

hospital. There have been several reports regarding

domyosarcoma) as primary cancer and were likely tothe detection of pathological variants of cancer pre­have pathogenic variants in TP53 6） were not includ­disposition genes in CCSs using the gene panel6）42）43）,

ed in this study.

but there has been no report of an SMN follow-up

Four participants (25 ％) developed secondary tu­

system routinely linking clinical sequencing for ger­mors at the time of participation in this study. Patientmline cancer predisposition genes.

1 had four malignant tumors by the age of 42 and met

No. 3, 2022

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Watanabe・Hirabayashi・Morita et al.

the Chompret criteria44） because a relative developed

recruited. In this system, the clinical sequencing andyoung-onset cancer. However, no pathogenic variants,

relevant genetic counseling costs approximately

including copy number abnormalities in TP53, were

53,000 JPY (about＄485), which is not covered by thedetected. She received both chemotherapy and allo-

health insurance system in Japan. We were con­

HSCT after a 12-Gy total body irradiation-based con­cerned that CCSs and their parents might be reluc­ditioning regimen for ALL. Chemotherapy at onset

tant to receive genetic services at their own expenseconsisted of cyclophosphamide, etoposide, pirarubicin,

because most of the costs of treatment for specificand mitoxantrone, which are at high risk for SMN. In

pediatric chronic diseases, including cancer, are cov­

addition, allo-HSCT at the time of relapse may beered by the health insurance system. Low estimatedassociated with SMN.

detection rates for pathogenic or likely pathogenic

The risk of CRC in individuals heterozygous for avariants and possible anxieties through the risk ofgermline MUTYH pathogenic variant was slightly in­

SMN and uncovering hereditary cancer predisposing

creased in large population-based and family-based

syndromes could have been negative factors for par­studies, while the frequency of colonic and upper gas­

ticipation in this study. However, the fact that 16

trointestinal polyps did not increase in 62 heterozy­

CCSs (43 ％) participated in this study suggests that

gotes for MUTYH

41）. Although a slightly increaseda certain proportion of CCSs and their guardians

cumulative risk for MUTYH heterozygotes for gastric,

would potentially like to know the risk of developing

hepatobiliary, endometrial, and breast cancers has been

SMN. A further questionnaire-based survey regard­

reported, other case-control studies did not find an

ing participation in this study to the remaining CCSs

association between MUTYH heterozygosity and risk

who did not accept the proposal might clarify the41）

for breast cancer or hepatocellular carcinoma . Basedcauses of their non-participation.

on the history of treatment and pathogenicity ofThis study has some limitations. First, the number

the variant, the patient was considered to have a re­of participants is small, and experiences of actionable

latively high risk of SMN and an SMN surveillancepathogenic variants have been lacking, which would

was proposed as a precautionary measure.

be required for discussing the efficacy of SMN sur­A questionnaire-based survey was conducted toveillance in this system. Second, the types of primary

comprehend the thoughts of CCSs and/or theircancer were biased, as 13 of 16 participants in theguardians regarding SMN, clinical sequencing, andcurrent study developed acute leukemias as primary

SMN surveillance. Anxiety about SMN did not change

cancer. Third, selection of the target genes (165 can­significantly before and after clinical sequencing,cer predisposition genes) might not have been suffi­

but all four CCSs who were found to have VUS show­

cient. It is presumed that more cancer predisposition

ed increased anxiety. This result suggests that thegenes will be newly discovered in the future, andpresence or uncertainty of variants in cancer pre­hence, it would be necessary to update the surveil­

disposition genes could increase anxiety about SMN for

lance guidelines as appropriate. Fourth, the estimat­

CCSs and their families, even after genetic counsel­

ed pathogenicity of the detected variants in theseing. Genetic counseling in the current system wouldcancer predisposition genes could change. Therefore,

require more careful anticipatory guidance for this

it would be useful to estimate the pathogenicity ofclinical sequencing (e.g., low detection rates, possibilities

detected variants on a regular basis (e.g., searchingof VUS) as well as follow-up services, including

the ClinVar®website at the time of the annual LTFU

variant interpretation and psychological aspects.

clinic). Fifth, specific interpretation of the detected

During the study period, the current clinical se­

variants may be difficult (e.g., a heterozygous variant

quencing-based surveillance system was proposed toin MUTYH might or might not be a risk for CRC or

37 CCSs and their families in the LTFU clinic, and 16

extraintestinal cancer depending on the relevant popu­of them wished to participate in this study and werelation or the study design).

164

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CCSs follow-up using clinical sequencing

In summary, our novel follow-up system for CCSs

study was supported by Project Mirai Cancer Re­

is presented, comprising germline clinical sequencing

search Grants in 2018 (Japan Cancer Society ; DM)of 165 cancer predisposition genes and relevant SMN

and Childhood cancer survivor follow-up research insurveillance. No pathogenic or likely pathogenic

2020 (Heart Link Working Project ; TW).

variants were detected among the 16 participants,

Disclosure

who mainly developed leukemia as a primary cancer,
and currently the efficacy of an SMN surveillance

YT and TK are members of an endowed chairsystem for CCSs could not be shown. The presence

named the “Division of Clinical Sequencing, Shinshu

or uncertainty of variants in cancer predisposition

University School of Medicine” sponsored by BML,

genes could increase anxiety about SMN in CCSs

Inc. and Life Technologies Japan Ltd. of Thermo

and their families. Further evaluation, including more

Fisher Scientific Inc.

CCSs with a wider spectrum of cancers, would be

Author Contribution

necessary to evaluate this system. Genetic counselingmight require careful anticipatory guidance for clini­

TW, DM, YN, and TK designed the study ; TY

cal sequencing and follow-up services, including

performed molecular investigation and interpreted

variant interpretation and psychological aspects.

the molecular data with TW and TK ; KH, DM, EO,
HM, SS, MT, and YN recruited participants and collect­

Acknowledgments

ed clinical information ; TW and KH combined and

We are grateful to the participants in this study.

interpreted the whole data (molecular and clinical

We also thank Dr. A. Fujikawa, MD, and Ms. Y.

investigation ; questionnaire-based survey) and wrote

Takiguchi for their technical support, and Editage

the manuscript ; all authors read and approved the(www.editage.com) for English language editing. This

final manuscript.

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