Weight gain after 35 linked to increased breast cancer risk

Chinese Academy of SciencesDec 11 2024

The body mass index (BMI) has long been used to measure body fat, but its influence on breast cancer risk is more complex than previously thought. While BMI offers a snapshot of body fat at a given moment, the gradual accumulation of weight over time paints a fuller picture of long-term metabolic changes that may influence cancer risk. Particularly concerning is the timing of weight gain—especially during hormone-sensitive periods such as early and late reproductive years and menopause. Despite the growing recognition of this link, research has remained limited, particularly in non-Western populations, calling for more inclusive studies to explore how weight gain at various life stages impacts breast cancer risk.

In a study (DOI: 10.20892/j.issn.2095-3941.2024.0172) published in Cancer Biology & Medicine, researchers at Seoul National University College of Medicine examined the effect of weight changes throughout the adult life cycle on breast cancer risk. The study, led by Dr. Daehee Kang and his team, focuses specifically on the menopausal transition, offering new insights into this critical area of women's health.

The study analyzed the weight trajectories of 73,192 Korean women, tracking their weight changes across five distinct life stages. It revealed that women who gained more than 10 kg after the age of 35 had a 41% increased risk of developing breast cancer. For premenopausal women, those who gained between 5 and 9.9 kg during this period faced an 89% higher risk, while those with a weight gain of 10 kg or more experienced a 2.23-fold increase in risk. The research also identified a V-shaped relationship between weight gain rate and breast cancer risk, with the highest risk observed in women gaining weight at a rate of 0.25-0.49 kg per year. These findings suggest that managing weight during mid-adulthood could play a pivotal role in reducing breast cancer risk.

Our research points to the critical period after age 35 as a potential window for weight management interventions aimed at breast cancer prevention. By addressing weight gain during mid-adulthood, we may be able to significantly reduce breast cancer risk and shift how we approach cancer prevention strategies for women."

Dr. Daehee Kang, study's lead investigator

The implications of these findings extend far beyond academic research. Identifying post-35 weight gain as a key risk factor offers new opportunities to develop targeted public health initiatives focused on weight management. Such initiatives could include dietary guidance, increased physical activity, and awareness campaigns aimed at empowering women to take control of their health. By focusing on preventive measures, these efforts could not only reduce the incidence of breast cancer but also shape the future of public health policies, transforming how societies tackle cancer prevention and improve overall well-being.