Why does oestrogen-only hormone therapy have such a small impact on breast cancer risk? A hypothesis

Potential Intervention Targets in Utero and Early Life for Prevention of Hormone Related Cancers

Hormone-related cancers have long been thought to be sensitive to exposures during key periods of sexual development, as shown by the vulnerability to such cancers of women exposed to diethylstilbestrol in utero. In addition to evidence from human studies, animal studies using new techniques, such as gene knockout models, suggest that an increasing number of cancers may be hormonally related, including liver, lung, and bladder cancer. Greater understanding of sexual development has also revealed the "mini-puberty" of early infancy as a key period when some sex hormones reach levels similar to those at puberty. Factors driving sex hormones in utero and early infancy have not been systematically identified as potential targets of intervention for cancer prevention. On the basis of sex hormone pathways, we identify common potentially modifiable drivers of sex hormones, including but not limited to factors such as obesity, alcohol, and possibly nitric oxide. We review the evidence for effects of modifiable drivers of sex hormones during the prenatal period and early infancy, including measured hormones as well as proxies, such as the second-to-fourth digit length ratio. We summarize the gaps in the evidence needed to identify new potential targets of early life intervention for lifelong cancer prevention.

Risk-reducing surgery in hereditary gynecological cancer: Clinical applications in Lynch syndrome and hereditary breast and ovarian cancer

Risk-reducing surgery (RRS) is defined as a prophylactic approach with removal of organs at high risk of developing cancer, which is performed in cases without lesions or absence of clinically significant lesions. Hereditary gynecological cancers for which RRS is performed include hereditary breast and ovarian cancer (HBOC) and Lynch syndrome. For HBOC, RRS in the United States (US) is recommended for women with mutations in the breast cancer susceptibility (BRCA)1 and BRCA2 genes and bilateral salpingo-oophorectomy (BSO) is generally performed. This procedure may reduce the risk of breast, ovarian, Fallopian tube and primary peritoneal cancer, although ovarian deficiency symptoms occur postoperatively. For Lynch syndrome, RRS in the US is considered for postmenopausal women or for women who do not desire to bear children and BSO and hysterectomy are usually performed. This approach may reduce the risk of endometrial and ovarian cancer, although ovarian deficiency symptoms also occur. For RRS, there are several issues that must be addressed to reduce the risk of cancer development in patients with HBOC or Lynch syndrome. To the best of our knowledge, this is the first review to discuss RRS with a focus on hereditary gynecological cancer.