Comparative study of breast cancer risk factors at Kenyatta National Hospital and the Nairobi Hospital

Breast cancer rates in high-income countries increased sharply with industrialization and urbanization but are now declining. Rates in low-income countries are instead rising after adoption of western type lifestyles. Some breast cancer risk factors are modifiable for prevention while others are not. The purpose of this study was to find out if wearing of brassieres and psychosocial stress had association with breast cancer occurrence. It was conducted from 09/08/11 to 23/12/12. Women with newly diagnosed breast cancer were matched with controls for age. A questionnaire was administered to detail patterns of brassiere wearing and marital stability, and some known breast cancer risk factors which could be confounders. Multivariate statistical models were used to discriminate confounders, and significance calculated at 95% confidence intervals. Three hundred and thirty-nine cases and 355 controls were included. The median age for cases was 48 years, range 25 to 80 years. The median for controls was 49, range 23 to 83 years. Age at onset of menses, parity, and the number of children who breastfed for at least 12 months was similar between cases and controls. There was no difference in level of education (p=0.783), and marital status (p=0.432) between cases and controls. On the other hand intensity of brassiere use (p<0.001), occupation (p<0.001), area of residence (p=0.045) diet (p=<0.01), duration of use of hormonal contraceptives (p<0.001), and family history of breast cancer (p=0.016), had association with breast cancer occurrence.