Key clinical point: Loss-of-function mutations in four breast cancer risk genes account for much of the disease among Nigerian women with the disease.
Major finding: Inherited mutations of the BRCA1, BRCA2, PALB2, or TP53 gene account for 12% of breast cancer in Nigerian women.
Study details: The Nigerian Breast Cancer Study comprised 1,136 women with invasive breast cancer and 997 controls.
Disclosures: Dr. Olopade had no financial disclosures. The study was largely funded by the National Institutes of Health and the Susan G Komen Foundation.
Olopade et al. J Clin Oncol. 2018 Aug 21. doi: 10.1200/JCO.2018.78.3977.
The findings of the Nigerian Breast Cancer Study make a case for large-scale breast cancer gene screening. But even in a wealthy country with good infrastructure, such a program would be dauntingly complex, Ophira Ginsburg, MD, and Paul Brennan, PhD, wrote in an accompanying editorial.
“Given the estimated 40,983 women in Nigeria younger than age 65 years who will be newly diagnosed with breast cancer in 2030, the estimated mutation carrier frequency for a high-risk gene of 11%-12% translates to approximately 5,000 women with breast cancer each year who might benefit directly from tailored risk-reducing strategies. Moreover, 50% of these women’s sisters and daughters would also stand to benefit,” they wrote.
However, 32 million women would need to be screened to find the 220,000 with one of the mutations – a task that is “clearly beyond the scope of most countries.
“Furthermore, women with pathogenic variants would require intensive follow-up and intervention strategies to reduce their risk of developing breast, ovarian/fallopian tube, and potentially other cancers depending on the gene involved. Importantly, this approach would not address the larger problem of the high breast cancer mortality among the vast majority of women without a pathogenic variant but who make up approximately 85% of the breast cancer burden.”
The World Health Organization recognizes this challenge; the agency doesn’t even recommend mammogram-based population screening unless there is a basic, reliable infrastructure including electricity, quality-assurance measures, referral and recall mechanisms, and monitoring and evaluation frameworks. But WHO does suggest some core elements to guide a country’s comprehensive cancer management strategy, including:
• Considering the whole continuum from prevention to palliation.
• Providing a sustainable strategic plan on the basis of the country’s cancer burden, risk factor prevalence, and the resources available to implement the plan.
• Developing an evidence-based approach generated by population-based cancer registries.
“As many countries improve their cancer systems, investing in human resources, infrastructure, monitoring, and evaluation, it is timely to consider how to evaluate readiness to undertake a population-level cancer genetics intervention and consider the core elements that should be in place to make a substantive effect on cancer mortality.”
Dr. Ginsburg is with the Perlmutter Cancer Center of New York University. Dr. Brennan is with the International Agency for Research on Cancer, Lyon, France.
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