Trial Information

Follow-Up Study of Women Evaluated and Treated for Infertility

BACKGROUND: We previously conducted a retrospective cohort study of 12,193 patients
evaluated for infertility between 1960-1988 at five clinical sites. Detailed information
abstracted from the medical records, along with questionnaires administered to located
patients and cancer incidence and mortality data derived from cancer registries and the
National Death Index, allowed us to examine cancer risk related to different causes of
infertility and treatments while controlling for other patient characteristics. Although
there were some increases of certain cancers related to various causes of infertility, we
generally did not observe substantial relationships related to use of different fertility
drugs. The one exception was some increased risk of uterine cancers with clomiphene use, of
interest given the drug's chemical similarity to tamoxifen. Our numbers of patients with
certain cancers (e.g., ovarian, uterine) were, however, limited and we had insufficient
power to evaluate subgroup effects (e.g., drug relationships among nulligravid women).

OBJECTIVES: We are therefore proposing an updated follow-up of these patients in order to
assess cancer risk in relation to causes of infertility and therapeutic regimens used to
treat these causes.

ELIGIBILITY: This study will attempt to gain an additional 10 years of follow-up among the
patients deemed eligible for the previous investigation. This includes women with both
primary and second infertility. Approximately 39% of the cohort previously were prescribed
clomiphene citrate, while 10% received gonadotrophins.

DESIGN: Passive follow-up will be attempted for patients who previously did not participate
and for whom only information available in clinic records could be retained. All other
patients will be traced for active as well as passive follow-up. Active follow-up will
involve requesting that patients complete a short questionnaire, whereas passive follow-up
will be via linkage to cancer registries and the National Death Index. While cancer risks
will be assessed in relation to the general population, the majority of comparisons will be
internal ones, involving the calculation of relative risks (RRs) associated with different
causes of infertility or treatment regimens while controlling for other cancer risk
predictors.