Anthropometric factors and breast cancer risk among urban and rural women in South India: a multicentric case-control study.

Breast cancer (BC) incidence in India is approximately twice as high in urban women than in rural women, among whom we investigated the role of anthropometric factors and body size. The study was conducted at the Regional Cancer Centre, Trivandrum, and in three cancer hospitals in Chennai during 2002-2005. Histologically confirmed cases (n=1866) and age-matched controls (n=1873) were selected. Anthropometric factors were measured in standard ways. Information on body size at different periods of life was obtained using pictograms. Odds ratios (OR) of BC were estimated through logistic regression modelling. Proportion of women with body mass index (BMI)>25.0 kg/m(2), waist size >85 cm and hip size >100 cm was significantly higher among urban than rural women. Risk was increased for waist size >85 cm (pre-menopausal: OR=1.24, 95% CI: 0.96-1.62; post-menopausal: 1.61, 95% CI: 1.22-2.12) and hip size >100 cm (pre-menopausal: OR=1.47, 95% CI: 1.05-2.06; post-menopausal 2.42, 95% CI: 1.72-3.41). Large body size at age 10 (OR=1.75, 95% CI: 1.01-3.03) and increased BMI (OR=1.33, 95% CI: 1.05-1.69 for 25.0-29.9 kg/m(2) and OR=1.56, 95% CI: 1.03-2.35 for 30+ kg/m(2)) were associated with pre-menopausal BC risk. Our data support the hypotheses that increased anthropometric factors are risk factors of BC in India.