BACKGROUND: Many studies conducted over the years have recognized the substantial epidemiologic evidence on the contribution of reproductive factors for the occurrence
of breast carcinoma, including parity. However, most studies evaluated relatively homogeneous populations, with a small number of women with high fertility,
and the association of very high parity with breast cancer remains poorly understood. Terefore, we addressed this topic in an African population characterized by
high fertility rates.
METHODS: We conducted a case-control analysis among women that were attending the Taimako breast and cervical cancer-screening centre, which is located in Nasarawa
state of North-Central Nigeria.
RESULTS: Among cases, 34.5% of the women were 39 years or less. About a quarter had ever used oral contraceptives, nearly half had attained menopause, and nearly two
thirds had parity higher than 4 (parity 5-6, 32.1%; parity 7-8, 25.0%, parity =9, 7.1%). Compared to women with parity 1-4 the risk of breast cancer tended to be higher
among nulliparous women (OR=3.44, 95%CI: 0.68-17.54), though it was lower among those aged =45 years (OR=1.43, 95%CI: 0.11-18.22) and higher in participants
aged >45 years (OR=12.07, 95%CI: 0.62-233.00). For women with higher parity, the OR estimates were similar for those with parity 5-6 (OR=2.54, 95%CI: 0.80-8.01)
and 7-8 (OR=2.65, 95%CI: 0.74-9.48).
CONCLUSION: Our results suggest that future increase in incident breast cancer cases in this setting may result from an improvement of screening and diagnostic services,
rather than from a dramatic but unlikely reduction in parity.