Risk factors for breast cancer for women in Punjab, Pakistan: Results from a case-control study

Over the last three decades an increase in the incidence of breast cancer has been observed in the previously low-risk Asian countries. This study is designed to determine the risk factors of breast cancer for Pakistani women as little information exists in this regard. A case-control study of 564 female breast cancer cases diagnosed at the two cancer hospitals at Lahore (INMOL and SKMCH) during the time period Jan 1, 1998 to Dec 31, 1998 was carried out. Four hundred and forty eight women aged 24-80 years out of 564 cases were complete with respect to defined criteria and were eligible for the study. Population-based controls were selected to match for age of cases in the ratio 1:2. The data were analyzed considering ‘all women’ and then separate analyses were done for ‘premenopausal’ and ‘postmenopausal women’. Women with family history of breast cancer, history of consanguineous marriage, smoking and high BMI (≥28) are at increased risk of breast cancer for all three groups. Early menarche (<13 years) was not a risk factor for this study. Late age at menopause (>45 years) was a strong determinant of breast cancer. Higher number of full-term pregnancies (>3) was protective for ‘all women’ and ‘premenopausal women’ but in case of ‘postmenopausal women’ the poor with higher number of pregnancies were significantly protected. Late age at first FTP (>25 years) is a significant risk factor for postmenopausal women.