RESUMO
Context: Breast cancer incidence rates are high in developed countries and much lower in less developed countries including India. Aims: The aim of the following study is to compare breast cancer incidence rates in rural, urban and metro regions of India and to estimate risk of developing breast cancer associated with residence in a rural area. Settings and Design: Descriptive and analytical study design. Materials and Methods: We extracted age adjusted incidence rate from 26 population-based cancer registries and data from hospital-based case-control study to estimate rate and risk ratio for developing breast cancer in an urban region compared with a rural residence. Statistical Analysis: The rate ratios and 95% confidence interval (CI) for developing breast cancer in the urban and metro region compared with rural registry of Barshi were estimated. The odds ratio (OR) and 95% CI for developing breast cancer in women residing in a rural region was estimated by fitting unconditional logistic regression using hospital-based case-control study data. Average annual percentage change in most recent 15 years (1996-2010) for Barshi (rural), Aurangabad (urban), and Mumbai (metro) cancer registry was obtained by fitting a log-linear model using joint point regression. Results: Living first 20 years of life in a rural area reduces the risk of breast cancer (OR = 0.65, 95% CI: 0.56-0.76). Conclusions: The current study demonstrates that lifestyle operative in a rural area is protective against risk of developing breast cancer.