Continuation of Follow-up of DES-Exposed Cohorts

Diethylstilbestrol (DES), a drug first synthesized in 1938, was administered to several
million pregnant women in the U.S. and Europe for the prevention of spontaneous abortion and
premature delivery. In 1971, Herbst reported a strong association between DES use in
pregnancy and the occurrence of vaginal clear cell adenocarcinoma (CCA) in exposed female
offspring. Animal models have demonstrated a range of DES effects on offspring exposed in
utero, including reproductive dysfunction, immune system changes, behavioral and sexual
abnormalities, and increases in various reproductive cancers in males and females. In the
mid-1970's, several separate cohorts of DES-exposed daughters and unexposed comparison groups
were followed for the occurrence of cancer, precursor lesions, and reproductive effects, but
systematic follow-up of these cohorts had ceased by 1990. In 1992, Congress passed a bill
(H;.R. 4178) mandating the continued follow-up of DES-exposed cohorts of mothers, daughters,
sons and grandchildren. The National Cancer Institute, in collaboration with five field
centers, reassembled previously studied cohorts of DES-exposed and unexposed mothers,
daughters and sons, and identified subjects with documented exposure status who had not been
studied previously, through familial links within the cohorts. Standardized baseline
questionnaires were mailed to cohort members to ascertain the risk of cancer and other
disorders. Pathology reports were collected for reported cancers and preneoplastic
conditions. Three separate phases of follow up have been conducted. Patients from the
Registry for Research on Hormonal Transplacental Carcinogenesis at the University of Chicago
will be added to the follow-up effort and mailed the questionaire used in the third phase of
follow-up. A cohort of daughters of women exposed and not exposed to DES in utero have been
added to the study to assess the effects of DES on third generation women.

The purpose of this study as a whole is to continue the follow-up, by means of mailed
questionnaires and medical record collection, which was begun during the first phase of the
study. Concern has arisen that DES-exposed daughters may be at higher risk of breast cancer.
Exposure to high levels of endogenous estrogen in utero has been hypothesized to increase the
risk of breast cancer and DES is a potent estrogen. Cancer risk in the sons will also
continue to be assessed, especially for increased risks of prostate cancer. Since the
offspring who were exposed to DES in utero are currently reaching their late forties, when
cancer rates begin to rise, it is important to continue the follow-up of these cohorts to
determine if there are long-term increases in cancer risk.

We are planning to add a biospecimen collection component to the study. We propose to conduct
a pilot study, nested within our ongoing combined cohort of DES-daughters, at Boston
University to determine the feasibility of recruiting women participating in our study for
phlebotomy and to investigate potential differences in the hormone metabolites and
methylation patterns of germline DNA in 60 of these samples representing three groups of
women: those exposed to high doses of DES prenatally, those exposed to low-doses of DES
prenatally, and unexposed. Hormone metabolites and DNA methylation will be assessed in
relation to DES exposure. Hormone metabolites will be measured at NCI s Frederick laboratory.
DNA methylation will be assessed by Dr. Shuk-Mei Ho, the Jacob G. Schmidlapp Chair of the
Department of Environmental Health, Director of the Center for Environmental Genetics, and
Co-Leader of the Hormonal Malignancies Program in the Joint Cancer Center, at the College of
Medicine in the University of Cincinnati, OH, and at Stephen Chanock s laboratory at NCI. The
findings of this pilot study may have profound implications for the mechanisms by which
endocrine disruption in the fetus influences human health. IRB approval of the data
collection protocol has been received from Boston University.

- INCLUSION CRITERIA:

Exposed daughters and unexposed daughters originally identified at: Baylor College of
Medicine, University of Southern California (USC), Gunderson Clinic, Mayo Clinic, and
Massachusetts General Hospital (MGH).

Male and female offspring of mothers who were enrolled in a clinical trial to assess the
effectiveness of DES at the University of Chicago.

Offspring of mothers who were treated with DES by an infertility specialist, Dr. Herbert
Horne, in the Boston area.

Offspring of DES-exposed mothers and unexposed mothers who were followed for breast cancer
risk during the 1980s.

Exposed sons and unexposed sons who were originally identified and followed at the Mayo
Clinic during the late1970's for the occurrence of cancer, genital abnormalities and
infertility.

Subjects from the Registry for Research on Hormonal Transplacental Carcinogenesis.