Breast cancer incidence and mortality worldwide have increased in cohorts of women born since 1900 for reasons not well understood. The incidence of female breast cancer varies markedly between countries and is highest in Northern Europe and the United States, intermediate in Southern and Eastern Europe, and lowest in Asia and the Far East. In Saudi Arabia, breast cancer is one of the most common malignancies among Saudi females. The objective of this study was to identify the most common risk factors among female cases of breast cancer in Riyadh Medical Complex (RMC).
Methodology
Thirty-three breast cancer cases and 65 controls, matched 2:1 according to age (± 5 years) and nationality, were involved in a hospital based case-control study. Odds ratios (ORs) were computed to measure the association between breast cancer risk factors and the study variables; a 95% confidence interval (CI) was used to evaluate statistical significance.
Results
Out of 33 cases, 18 (55%) were Saudis. The mean age at diagnosis was 46 years (range 27-76) for cases; compared to 43 years (range 24-73) for controls. Significant associations were observed between breast cancer and late age at menopause (50 years or older), induced abortion, and abortion at first pregnancy (ORs= 2.1 for each). Breast cancer risk was reduced by breastfeeding (OR=0.43) and prolonged lactation for ≥100 months (OR=0.29). There was no significant difference between breast cancer and total months of breastfeeding among postmenopausal women. Late age at menarche and parity were associated with reduced risk (ORs=0.4 and 0.38 respectively). The number of full-term pregnancies showed only weak association with decreased risk. Two cases gave a history of unilateral breastfeeding; subsequently, they developed cancer in the breast not used for nursing. Increased body mass index (≥30) and decreased physical activity (OR=1.2) were both associated with increased risk of breast cancer. An increased odds ratio was observed among women with first and second-degree family history of breast cancer (ORs= 2.7 and 2.4 respectively). Family history of cancer (other than breast) was also associated with breast cancer risk (OR=1.6). No significant associations were observed between breast cancer risk and contraceptive use (OR=0.63). Increased risk for breast cancer emerged in women with history of benign breast disease (OR= 11.8).
Conclusion
Breast cancer risk factors identified among females in RMC were similar to those stated in the literature. Breastfeeding has a protective effect against breast cancer. However this protective effect does not differ by varying total months of breastfeeding. Lactation for ≥100 months gives a protective effect against breast cancer. Conducting health education programs to increase public awareness and early detection of breast cancer by mammography screening and breast self examination should be encouraged by the Ministry of Health. As no previous studies have been conducted in Saudi Arabia to identify risk factors for breast cancer, it is mandatory to conduct more similar studies, involving more of the population.