Lactation in relation to postmenopausal breast cancer

Area of Science:

• Epidemiology
• Oncology
• Reproductive Health

Background:

• Lactation demonstrates an inverse association with breast cancer risk, particularly in premenopausal women.
• Certain breastfeeding patterns, like prolonged duration and early age at first lactation, are linked to risk reduction.
• These associations have not been consistently observed for postmenopausal breast cancer.

Purpose of the Study:

• To investigate the relationship between breastfeeding characteristics and postmenopausal breast cancer risk.
• To determine if lactation duration and timing influence breast cancer risk in older women.

Main Methods:

• A multicenter, population-based case-control study involving 3,633 postmenopausal breast cancer cases and 3,790 controls (aged 50-79).
• Data collected via telephone interviews on lactation history and other breast cancer risk factors.
• Statistical analysis adjusted for age, parity, age at first birth, and other relevant factors.

Main Results:

• Breastfeeding for at least two weeks was associated with a modest reduction in postmenopausal breast cancer risk (RR=0.87).
• A longer cumulative duration of lactation showed a suggestion of inverse association with risk (RR=0.73 for ≥24 months).
• The protective effect appeared to persist for up to 50 years after first lactation; age at first lactation was not consistently associated with risk.

Conclusions:

• Lactation may confer a slight, potentially long-lasting protective effect against postmenopausal breast cancer.
• Findings suggest that breastfeeding duration is a significant factor in this protective association.
• Further research may elucidate the biological mechanisms underlying lactation's role in breast cancer prevention.