A Multicenter Matched Case Control Study of Breast Cancer Risk Factors among Women in Karachi, Pakistan

Background: Breast cancer (BC), the most common female cancer in Pakistan, is associated with a very highmortality. However, the roles of individual risk factors for BC among Pakistani women are still controversial. Toassess potential risk factors for BC, a matched case-control study was conducted in two tertiary care hospitals ofKarachi, Pakistan. Materials and
Methods: The study population included 297 pathologically confirmed incidentcases of BC patients diagnosed between January 2009 and December 2010. 586 controls without any history ofBC were matched on a hospital basis, within 5 years of patient ages.
Results: Family history of BC (MOR=1.72;95%CI: 1.10, 2.80 for first degree vs. none), single marital status (MOR=1.55; 95%CI: 1.10, 2.39 for singlewomen vs. married women), older age at menopause (MOR=3.92; 95%CI: 2.52, 6.18 for menopausal womenaged below 45 years, MOR=6.42; 95%CI: 3.47, 11.98 for menopausal women above 45 years of age comparedwith premenopausal women) conferred an increased risk of BC for women. Increasing parity decreased therisk of BC (MOR=0.90; 95%CI: 0.85, 0.97 for each live birth). Intake of Vitamin D supplements (MOR=0.30;95%CI: 0.12, 0.81 for <3 years and MOR=0.27; 95%CI: 0.13, 0.56 for >3 years) was protective compared tonon-users of Vitamin D.
Conclusions: This study confirmed only few of the recognized risk factors in Pakistaniwomen. The protective effect of Vitamin D is important from public health perspective and needs to be furtherexplored through a randomized controlled trial.