A Follow-up Study of Women Evaluated and Treated for Infertility
Condition: Ovarian Cancer; Breast Cancer; Endometrial Cancer; Thyroid Cancer; Colorectal Cancer, Melanoma
MeSH terms: Endometrial Neoplasms; Infertility
Study type: Observational

Summary: 
      To assess the relations of infertility causes and treatment to cancer risk, we will conduct a
      retrospective cohort study of approximately 12,000 women evaluated for infertility between
      1965-1988. These women will be ascertained from several large infertility clinics and private
      practices in various geographic locations in the United States: Boston, Chicago, Detroit, New
      York, and Palo Alto. These practices were selected on the basis of their having large number
      of patients who received ovulation stimulating drugs many years in the distant past.
      Abstractors reviewed clinic medical records to identify eligible study participants and
      abstract data needed to classify causes of infertility and document therapies employed. Using
      a variety of tracing sources (including the National Death Index, credit bureaus, and
      postmasters), the vital status and location of the study subjects were determined. Subjects
      who were traced and identified as alive are being sent a detailed questionnaire that requests
      information on their health status as well as on a number of lifestyle practices. For
      subjects who report a cancer, medical verification is being sought from the diagnosing
      physicians and/or facilities. Death certificates are being sought for deceased subjects.
    

Detailed description: 
      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 therefore conducted 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 gained an additional 10 years of follow-up among the patients deemed
      eligible for the previous investigation. This included 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 was attempted for patients who previously did not participate and
      for whom only information available in clinic records could be retained. All other patients
      were traced for active as well as passive follow-up. Active follow-up involved requesting
      that patients complete a short questionnaire, whereas passive follow-up was via linkage to
      cancer registries and the National Death Index. While cancer risks were assessed in relation
      to the general population, the majority of comparisons were 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.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Subjects were enrolled based on treatment at fertility clinic.@@@
      
Keywords: Gonadotropins; CLOMIPHENE; Ovulation-Stimulating Drugs; Natural History