Cancer risk after evaluation for infertility.

Area of Science:

• Reproductive Endocrinology
• Oncology
• Epidemiology

Background:

• Previous research suggested a link between progesterone deficiency in infertile women and increased breast cancer risk.
• The etiology of various cancers in relation to infertility causes requires further investigation.

Purpose of the Study:

• To evaluate the association between different causes of infertility and subsequent cancer risk.
• To specifically examine the relationship between progesterone deficiency and breast cancer risk in infertile women.

Main Methods:

• A retrospective cohort study of 2,335 women evaluated for infertility between 1935 and 1964 at the Mayo Clinic.
• Analysis of cancer incidence using standardized incidence ratios (SIR) and comparison of cancer risk between women with and without progesterone deficiencies.

Main Results:

• Overall cancer risk was similar to expected frequencies, except for thyroid (SIR = 2.6) and other endocrine gland cancers (SIR = 6.7).
• Women with progesterone deficiencies showed a 20% higher overall cancer risk, with excesses in lung, cervix, ovary, thyroid cancers, and melanoma.
• No elevated breast cancer risk was observed in women with progesterone deficiencies (SIR = 0.9) or other infertility causes (SIR = 1.0).

Conclusions:

• The study does not support a link between progesterone deficiency and elevated breast cancer risk in infertile women.
• Progesterone deficiency may be implicated in the etiology of other cancers, including thyroid cancer and melanoma.
• Further research is needed to clarify the role of progesterone deficiency in the development of specific cancer types.