Endocrine Abstracts

Introduction: The contribution of reproductive factors to breast cancer (BC) susceptibility requires further investigation. This study aims to explore the potential link between early puberty (menarche) and the risk of breast cancer in women.

Aim: This study systematically reviews research conducted between 2000 and March 2023, aiming to evaluate the association between early/precocious puberty and the incidence of BC.

Methods: A comprehensive search was performed across databases including Medline, PubMed, Google Scholar, and Web of Science to identify relevant studies. The review encompassed a variety of study designs, including metanalyses, prospective studies, and case-control studies.

Results: A total of 12 studies were analyzed: A comprehensive analysis of 117 epidemiological studies, involving 118,964 women with invasive breast cancer and 306,091 controls, demonstrated that younger age at menarche correlated with an increased BC risk. Each year younger at menarche was associated with a 5% increase in relative breast cancer risk, particularly for luminal A tumors. The risk rose by a factor of 1.050for each year younger at menarche. Endogenous ovarian hormones appeared more influential for estrogen receptor-positive disease and lobular tumors. A case-control study of 237 BC cases and 237 age-matched controls found that early menarche (OR =1.60, 95% CI: 1.08–2.38) significantly heightened breast cancer risk. A prospective US cohort study on women aged 35–74 without BC history but with a diagnosed sister revealed that early ages at thelarche and menarche were positively associated with BC risk. Women with both early thelarche and menarche exhibited a 30% higher risk of breast cancer compared to those without these risk factors. Multiple investigations consistently indicate that commencing menstruation before the age of 11 increases BC risk, while later menarche (14 years) reduces the risk. Sister-matched case-control research involving 1,406 women diagnosed with BC before age 50 and 1,648 controls reaffirmed the relationship between older age at menarche and reduced young-onset breast cancer risk. A study involving 1811 pairs of female twins with BC demonstrated that the twin with earlier puberty was more likely to receive the diagnosis of BC first. The Collaborative group on hormonal factors reported up to an 18% risk reduction in girls with late menarche (≥13) compared to those starting menstruation at 11.

Conclusion: The collective evidence supports the notion that earlier ages at thelarche, and menarche may heighten susceptibility to BC and add an advantage to hormonal suppressive therapy.