A nationwide population study recently published in the journal BMC Women's Health shows that if obese and physically inactive women sit for a long time, the incidence of breast cancer will increase significantly, and regular physical exercise can effectively eliminate this risk. This finding provides an important basis for the prevention of breast cancer in obese women. The study

was led by a team from Meizhou People's Hospital in China and analyzed 9,706 obese women based on data from the National Health and Nutrition Examination Survey (NHANES) of the United States. The subjects were divided into four groups according to the daily sitting time: less than 4 hours, 4-6 hours, 6-8 hours, and more than 8 hours. The results showed that among obese women who lacked exercise, the longer the sitting time, the higher the risk of breast cancer-compared with those who sat for less than 4 hours a day, the fully adjusted odds ratios (OR) of the groups sitting for 4-6 hours, 6-8 hours and more than 8 hours were 2.56, 2.12 and 2.43, respectively, showing a nonlinear dose-response relationship. It is worth noting that this association was not observed in obese women who maintained exercise habits.

The study further pointed out that the risk associated with long-term sitting is particularly prominent in women aged 60 years and above, non-Hispanic whites, those with higher education, postmenopausal women, and severely obese people with a BMI ≥ 35kg/m². Socioeconomic factors also have an impact: obese women with family income below the poverty line (income to poverty ratio <1.3) have a more significant increase in the risk of cancer caused by long-term sitting.

The researchers speculate that sedentary behavior may increase hormone levels through obesity, insulin resistance, and systemic inflammatory responses, thereby increasing the risk of breast cancer. Regular exercise can regulate sex hormone and metabolic hormone levels, reduce visceral fat, improve insulin sensitivity, and reduce inflammation, thereby offsetting the negative effects of sitting.

The study emphasized that limiting daily sitting time to less than 4 hours and maintaining exercise habits may be an effective strategy for obese women to reduce the risk of breast cancer. However, the study used a cross-sectional design and could not confirm the causal relationship between sitting and breast cancer, which needs to be verified through longitudinal studies in the future. In addition, breast cancer diagnosis data rely on self-reporting by subjects, which may be biased.

The research results have been published in BMC Women's Health, providing scientific reference for the formulation of targeted intervention measures in the field of public health.