Breast cancer risk after full-term pregnancies among African women from Nigeria, Cameroon, and Uganda.

BACKGROUND: The breast cancer (BC) risk profiles of African women differ significantly from those of women of European ancestry. African women are younger at the age of onset and tend to have high parity. The purpose of this study was to examine the relationship between full-term pregnancy (FTP) and the risk of BC. METHODS: A case-control study was conducted among 1995 women with invasive BC and 2631 controls in Nigeria, Cameroon, and Uganda. Odds ratios (ORs) for individual ages at FTP according to the time since delivery were calculated and adjusted for confounders. A fitted spline model was used to assess the impact of the number of pregnancies on BC risk. RESULTS: In comparison with a nulliparous woman, a parous woman with her first FTP at 20 years showed an OR of 0.76 (95% confidence interval [CI], 0.57-0.99) for developing BC in the following 5 years. Ten years later, this risk was 0.76 (95% CI, 0.58-0.99) and 0.76 (95% CI, 0.58-0.98) for women aged 25 and 30 years, respectively. Similarly, a parous woman with 1 pregnancy had an OR of 0.69 (95% CI, 0.49-0.96), whereas the OR was 0.66 (95% CI, 0.48-0.91) with 2 or 5 pregnancies and 0.67 (95% CI, 0.47-0.94) with 6 pregnancies in comparison with nulliparous women. CONCLUSIONS: In contrast to studies in women of European ancestry, this study showed no transient increase in the risk of developing BC after FTP among African women. Further studies are needed to examine the impact of reproductive factors on early-onset BC in African women.

Breast Cancer Knowledge Assessment of Health Workers in Ibadan, Southwest Nigeria.

PURPOSE: Breast cancer is the most common cancer among women, and in low- to middle-income countries late-stage diagnosis contributes to significant mortality. Previous research at the University College Hospital, a tertiary hospital in Ibadan, Nigeria, on social factors contributing to late diagnosis revealed that many patients received inappropriate initial treatment. METHODS: The level of breast cancer knowledge among health practitioners at various levels of the health system was assessed. We developed a tool tailored to local needs to assess knowledge of symptoms, risk factors, treatments, and cultural beliefs. The recruitment included doctors, nurses, and pharmacists in public hospitals, physicians and pharmacists in private practice, nurses and health care workers from primary health care centers, community birth attendants, and students in a health care field from state schools. RESULTS: A total of 1,061 questionnaires were distributed, and 725 providers responded (68%). Seventy-eight percent were female, and > 90% were Yoruba, the dominant local ethnic group. The majority were Christian, and 18% were Muslim. Median knowledge score was 31 out of 56, and the differences in scores between health care worker types were statistically significant (P < .001). Nearly 60% of the participants believed breast cancer is always deadly. More than 40% of participants believed that keeping money in the bra causes breast cancer, and approximately 10% believed that breast cancer is caused by a spiritual attack. CONCLUSION: Our questionnaire revealed that, even at the tertiary care level, significant gaps in knowledge exist, and knowledge of breast cancer is unacceptably low at the level of community providers. In addition to efforts aimed at strengthening health systems, greater knowledge among community health care workers has the potential to reduce delays in diagnosis for Nigerian patients with breast cancer.

Inherited Breast Cancer in Nigerian Women.

PURPOSE: Among Nigerian women, breast cancer is diagnosed at later stages, is more frequently triple-negative disease, and is far more frequently fatal than in Europe or the United States. We evaluated the contribution of an inherited predisposition to breast cancer in this population. PATIENTS AND METHODS: Cases were 1,136 women with invasive breast cancer (mean age at diagnosis, 47.5 ± 11.5 years) ascertained in Ibadan, Nigeria. Patients were selected regardless of age at diagnosis, family history, or prior genetic testing. Controls were 997 women without cancer (mean age at interview, 47.0 ± 12.4 years) from the same communities. BROCA panel sequencing was used to identify loss-of-function mutations in known and candidate breast cancer genes. RESULTS: Of 577 patients with information on tumor stage, 86.1% (497) were diagnosed at stage III (241) or IV (256). Of 290 patients with information on tumor hormone receptor status and human epidermal growth factor receptor 2, 45.9% (133) had triple-negative breast cancer. Among all cases, 14.7% (167 of 1,136) carried a loss-of-function mutation in a breast cancer gene: 7.0% in BRCA1, 4.1% in BRCA2, 1.0% in PALB2, 0.4% in TP53, and 2.1% in any of 10 other genes. Odds ratios were 23.4 (95% CI, 7.4 to 73.9) for BRCA1 and 10.3 (95% CI, 3.7 to 28.5) for BRCA2. Risks were also significantly associated with PALB2 (11 cases, zero controls; P = .002) and TP53 (five cases, zero controls; P = .036). Compared with other patients, BRCA1 mutation carriers were younger ( P < .001) and more likely to have triple-negative breast cancer ( P = .028). CONCLUSION: Among Nigerian women, one in eight cases of invasive breast cancer is a result of inherited mutations in BRCA1, BRCA2, PALB2, or TP53, and breast cancer risks associated with these genes are extremely high. Given limited resources, prevention and early detection services should be especially focused on these highest-risk women.

Risk factors for pregnancy-associated breast cancer: a report from the Nigerian Breast Cancer Study.

PURPOSE: Little is known about risk factors for pregnancy-associated breast cancer (PABC), diagnosed during pregnancy or postpartum. METHODS: We enrolled 1715 premenopausal women from the Nigerian Breast Cancer Study from 1998 to 2011. Based on recency of last pregnancy from diagnosis, breast cancer cases were categorized as (1) PABC diagnosed 2 years or longer postpartum, (2) PABC diagnosed 3 to 5 years postpartum, or (3) non-PABC diagnosed more than 5 years postpartum. Controls were matched to cases on recency of last pregnancy. Multiple logistic regressions were performed comparing cases and controls within each group. RESULTS: Of the 718 cases, 152 (21.2%) had PABC 2 or more years postpartum, and 145 (20.2%) 3 to 5 years postpartum. Although not statistically significant, women with higher parity tend to have an elevated risk of PABC but reduced risk of non-PABC (p for heterogeneity = 0.097). Family history of breast cancer might be a strong predictor particularly for PABC 2 or more years postpartum (odds ratio, 3.28; 95% confidence interval, 1.05-10.3). Compared with non-PABC cases, PABC 2 or more years postpartum cases were more likely to carry BRCA1/2 mutations (P = .03). CONCLUSIONS: Parity may have different roles in the development of PABC versus other premenopausal breast cancer in Nigerian women. Prospective mothers with multiple births and a family history of breast cancer may have an elevated risk of breast cancer during their immediate postpartum period.