RISK FACTORS ASSOCIATED WITH BREAST CANCER AMONG WOMEN IN TWO REFERRAL CENTRES IN NIGERIA

Abstract

Breast Cancer (BC) is a common cause of death among Nigerian women. Past studies suggest that diet, lifestyle and environmental pollutants are more important risk factors in the aetiology of cancers. Identifying some of these factors is vital to directing strategies for intervention in specific locations. This study was carried out to determine risk factors associated with BC among women in two referral hospitals in Nigeria. A case-control study was carried out among 266 women aged 20-80 years. Warri Central Hospital and University College Hospital were purposively selected based on their Management's approval to be part of the study. 35 and 30 cases of BC were recruited from the hospitals, respectively. For the controls, consenting women in Warri ( 111) and Ibadan (90) were enlisted from neighbouring households in the same enumeration areas as the cases. Cases and controls were matched in the ratio of 1:3 for age and duration of stay in area of residence. A semi-structured questionnaire was used to collect data on socio-demographic characteristics, family history of breast cancer, dietary pattern, nutritional status, physical activity and environmental factors. Food frequency questionnaire was used to assess high risk food intake where consumption of high calorie-containing food ≥3 times week was categorised as high and <3 times a week as low. Body mass index (kg/m2) and waist-to-hip ratio were used to determine respondent's nutritional status and abdominal fat, respectively. Physical activity was measured using WHO standard (where exercise for at least a three times per week was categorised as good while less than three times a week as poor. Frequency of exposure to automobile, generator, industrial fumes and effluents was categorised qualitatively as daily, occasional and rarely. Data were analysed using descriptive statistics, Chi-square test and logistic regression at 5% level of significance. The mean age of the respondents was 48.7±11.8 years. Family history of breast cancer was reported by 6.2% of the cases and 5.0% of controls. Dietary pattern revealed that cases (69.2%) and controls (54.7%) significantly had high risk consumption pattern for high calorie containing foods. Cases were significantly more overweight than the controls (41.5% versus 21.4%). Higher proportion of controls (58.6%) than the cases (22.9%) had high risk abdominal obesity. Significantly more controls than cases had good exercise (17.9% versus 6.2%). The odds of developing breast cancer was four times higher among women who reported daily exposure to fumes from automobiles and generators than those who were rarely exposed (OR-=4.40, CI= 1.25-15.57), seven times higher among women who reported occasional exposure to wastes from operating industries than those who were rarely exposed (OR=6.91, CI=2.87-16.66). Major risk factors for breast cancer among women in Warri and Ibadan were lack of exercise, high calorie containing food intake, environmental pollutants and nutritional status. Health education to improve knowledge of self-protection against pollutants and adoption of healthy dietary habits may reduce risk of breast cancer.