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 histologicallyconfirmed
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.