Rates of Inherited Breast Cancer in Nigerian Women


Key Points

  • 1 in 8 cases of invasive breast cancer was associated with inherited mutations in BRCA1, BRCA2, PALB2, or TP53.
  • BRCA1 and BRCA2 mutations were the greatest contributors to risk.

In a study reported in the Journal of Clinical Oncology, Zheng et al found a high frequency of inherited breast cancer among Nigerian women, with presence of deleterious mutations posing very high risk of disease.

As noted by the investigators, “…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.”

Study Details

The study involved 1,136 women with invasive breast cancer (mean age at diagnosis = 47.5 years) identified in Ibadan, Nigeria, and 997 controls without breast cancer (mean age at interview = 47.0 years) from the same communities. BROCA panel sequencing was used to identify loss-of-function mutations in known and candidate breast cancer genes.

Deleterious Mutations and Risk

Among the 577 patients with data on tumor stage, 497 (86.1%) were diagnosed at stage III (n = 241) or IV (n = 256). Among 290 patients with data on hormone receptor and HER2 status, 133 (45.9%) had triple-negative disease.

Among all cases, 167 patients (14.7%) vs 18 controls (1.8%) harbored a known deleterious mutation in a breast cancer gene, including 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. BRCA1 mutation (odds ratio [OR] =23.40, P < .001) and BRCA2 mutation (OR = 10.76, P < .001) were the greatest contributors to risk of disease. Increased risk for patients vs controls was also associated with PALB2 mutation (11 cases vs 0 controls, P = .002) and TP53 mutation (5 cases vs 0 controls, P = .036). Compared with other patients, those with BRCA1 mutation were younger (P < .001) and more likely to have triple-negative breast cancer (P = .028).

The investigators concluded, “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.”

The study was supported by grants from the National Institutes of Health, Susan G. Komen for the Cure, Breast Cancer Research Foundation, Ralph and Marian Falk Medical Research Trust, and John and Editha Kapoor Charitable Foundation.

Olufunmilayo I. Olopade, MD, of the Center for Clinical Cancer Genetics and Global Health, University of Chicago, is the corresponding author for the Journal of Clinical Oncology article.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.