Testimony of Adi F. Gazdar MD

U.S. House of Representatives

Subcommittee on Human Rights and Wellness of the Committee on Government
Reform

Hearing entitled "The SV40 Virus: Has tainted polio vaccine caused an
increase in Cancer?"

Washington DC, Sept. 10, 2003

Mr. Chairman and members of the Subcommittee,

I welcome the opportunity to address you on the subject of SV40
contamination of human polio vaccine and the role of the virus in the
causation of human cancers.

For more than 30 years, an increasing number of reports have documented
the presence of a monkey virus, simian virus 40 or SV40 in certain
highly specific forms of human cancers. More than 100 reports from more
than 60 laboratories world wide have documented the presence of SV40 in
human tumors, although there have been a few negative studies.
Approximately 40 -- 50% of four types of human tumors, brain tumors,
bone tumors, mesotheliomas and lymphomas contain footprints of the
virus. We have recently extended these findings to human leukemias. Of
great interest, injection of the virus into hamsters results in an
identical tumor spectrum. These tumors will occur in an estimated
113,600 and kill 64,400 Americans this year. Thus approximately 50,000
tumors that occur in this country this year will contain evidence of
SV40.

How did a monkey virus infect humans? The major source appears to be
from stocks of polio vaccine, which was prepared in monkey kidney cells
from the years 1955 to 1963. However, some evidence exists that the oral
vaccines after this date may also have contained live SV40. Some
investigators have suggested that following the administration of
contaminated vaccines, SV40 may have established itself in the human
population, and that the virus may be spread from human to human.
However, this hypothesis remains to be tested.

SV40 is one of the most potent cancer causing agents discovered for
human cells. It contains genes that take control of the growth
mechanisms of infected cells, converting normal cells to tumor cells.
The virus is widely used as a laboratory tool, raising the possibility
of artificial contamination. Initially I was highly skeptical about the
accuracy of the reports, and decided to investigate the matter
personally. Using a technique known as microdissection I was amazed to
find the presence of the virus in the tumor cells but not in the
adjacent non malignant tissues. These experiments ruled out the
possibility of contamination or laboratory artifact. I went from a
skeptic to a believer. My assessment was supported by a review conducted
by a panel of scientists at the National Cancer Institute and chaired by
Dr. J. Pagano and M. Wong. This panel concluded that it had been
definitively proven that SV40 was present in some human tumors. In
agreement with my assessment, the same panel ruled out the possibility
that SV40 detection was caused by laboratory artifacts.

However, the presence of a virus in a given cancer does not prove
causation because the virus might simply be an innocent bystander, or be
the cause or one of the causes of the tumor. To link a given carcinogen
to the overall increase of a type of cancer, scientists use
epidemiological analyses. To link a carcinogen to a specific cancer in a
specific patient, scientists use molecular pathology. These two medical
sciences are complementary: epidemiology allows us to identify the
overall impact of a carcinogen in the human population, while molecular
pathology studies the effect of a carcinogen in a specific patient or
tumor.

The Institute of Medicine reviewed the epidemiological studies linking
SV40 to human cancer and concluded that the epidemiologic studies are
flawed. This conclusion was based on the observation that we are
currently unable to clearly identify in which years individuals received
the vaccine, who received contaminated stocks and who did not. In
addition, among those who received contaminated vaccines some received
stocks with low amounts of SV40 while others received stocks with high
amounts of SV40 and we cannot identify these cohorts. Finally a highly
reliable blood test for evidence for SV40 exposure has not been
identified which further complicates epidemiologic studies.

*Because the epidemiologic evidence is unsatisfactory, the evidence is
inadequate to either accept or reject a causal relationship.*

*The biological evidence is strong that SV40 is a cancer causing virus*

*The biological evidence is of moderate strength that SV40 exposure
could lead to cancer in humans under natural conditions.*

Similar conclusions were reached by an international panel of experts
who met in Chicago in 2001.

Recent molecular pathology studies from my laboratory and others has
conclusively demonstrated that SV40 associated tumors have different
properties than similar tumors that lack the virus. Moreover, it has
been recently proven that SV40 causes specific molecular alterations in
human mesothelial cells and mesotheliomas. These findings conclusively
identify SV40 as a pathogen, not a passenger when present in
mesothelioma. These studies provide very strong evidence that SV40
contributes towards cancer causation in some patients.

Why have we failed to make greater progress in this field? The major
reason is lack of funding. Governmental agencies have failed to target
this issue and have provided only token funds to a handful of
scientists. Even some of the worlds experts on SV40 have failed to
obtain government funding to study this issue. A major effort is needed
both on the part of scientists and of the funding agencies to
investigate an important health issue that may affect many thousands of
Americans every year.