RESUMO
INTRODUCTION: Breast cancer is the commonest cancer for females in Malaysia, with a prevalence of 86.2 per 100,000 women in 1996. Breast cancer mortality rate shows an increasing trend in Malaysia from 0.61 in 1983 to 1.8 per 100,000 women in 1992. The aim of this study was to identify the risk factors for breast cancer in women in Malaysia. METHODS: A matched case-control study was carried out at referral hospitals in Kelantan from July 2000 to June 2001. A standardised questionnaire that comprised socio-demographical factors, obstetrical and gynaecological histories, anthropometric measurements, and other potential risk factors for breast cancer, was used to interview 147 histologically-confirmed breast cancer patients and 147 controls. Controls were non-breast cancer patients who were matched for age and ethnicity, and excluded those with malignancies, or having gynaecological, hormonal or endocrine problems. Simple and multiple conditional logistic regressions were used for analyses. RESULTS: Factors contributing toward increased risk of breast cancer were nulliparity (odds ratio [OR] of 15.3; 95 percent confidence interval [CI] of 3.2, 72.4), overweight (OR of 2.1; 95 percent CI of 1.1, 3.9), family history of breast cancer (OR of 4.3; 95 percent CI of 1.3, 14.1) and previous use of oral contraceptives (OR of 2.5; 95 percent CI of 1.3, 4.8). CONCLUSION: This study reconfirmed that similar risk factors identified in Western populations were responsible for the occurrence of breast cancer in Kelantan. It also supported the theory that breast cancer occurrence was related to oestrogen exposure and familial factors. It suggested the importance of having children, maintaining ideal body weight and caution for oral contraceptive users and women with a family history of breast cancer.
