Washboard abs, it now appears, are not just desirable for cosmetic reasons. A higher waist circumference and waist-to-hip ratio — or central obesity — can increase the risk of breast cancer by three times among South Asian women, a new study has found.
The study, published recently by Elsevier, was conducted at the Tata Memorial Hospital and cites central obesity as a key risk factor for breast cancer among both premenopausal and postmenopausal women. Doctors who authored the study say the findings have a strong public health message — to control that expanding waistline, irrespective of age.
The study also busts the BMI (body mass index) link to breast cancer. “High BMI protects pre-menopausal women from breast cancer, while a high BMI in post-menopusal women increases the risk. So, BMI is not an indicator. But central obesity, which is based on waist circumference, increases the risk three-fold for all kinds of breast cancers among both pre- and post-menopausal women,” Dr. Rajesh Dikshit, professor of epidemiology and in-charge, Public Health, Tata Memorial Centre, who has co-authored the study, told The Hindu on Wednesday.
A flabby abdomen is a breast cancer risk for all tumour subtypes, says the study. “Furthermore, the association of central obesity with increased insulin levels and insulin-like growth factors may stimulate the growth of breast cancer cells,” it states.
Conducted over nearly five years, the study had participants from across India, but a majority of them were from western parts of the country. The participants mapped their increase in body size (based on pictograms they were shown) from the time they were 10.
Accelerated growth in the 10-20-year age category — be it weight or height — was identified as cause for concern. “If there is a sudden increase in weight from 10 to 20 years, it is reflective of accelerated growth and there is a risk of pre-menopausal breast cancer,” said Dr. Dikshit, emphasising a point made in the study — it is not just the weight but the distribution of fat in the body. “Our results indicate that distribution of body fat, rather than BMI, is a more important risk factor for breast cancer in this Asian population,” the study says.
Dr. Dikshit further said that even if a woman’s BMI is low or normal, but central obesity is high, she is at risk, pointing to the pattern observed in India where even lean women tend to have paunches. The study points out that a large number of women enrolled into the study had a normal BMI but a high waist-to-hip ratio. “The relationship between obesity and breast cancer is complex, with different ethnic populations showing different patterns of risk,” the study states.
The study has been authored by the Centre for Cancer Epidemiology at Tata Memorial Centre, Munbai, Center for Global Health, US National Cancer Institute, among other premier institutions.
