Female breast cancer is the most commonly diagnosed cancer in the world, with wide variations in reported survival by country. Women in low-income and middle-income countries (LMICs) in particular face several barriers to breast cancer services, including diagnostics and treatment. Memorial Sloan Kettering Cancer Center’s Hedvig Hricak, MD, PhD, and Larry Norton, MD, joined with researchers from the Harvard T.H. Chan School of Public Health, (Rifat Atun, MBBS, MBA, DIC, and Zachary Ward, PhD) and other international institutions, to estimate the potential impact of scaling up the availability of treatment and imaging modalities on breast cancer survival globally, together with improvements in quality of care. The team of international experts estimated that this combination could improve global 5-year net breast cancer survival by nearly 15 percentage points.
The researchers estimated that 5-year net survival for women diagnosed with breast cancer in 2018 was nearly 70 percent, but that there exist extremely large disparities in survival depending on where a woman lives. It is estimated that women in high-income countries have 5-year net survival of 87 percent, compared to only 3.5 percent in low-income countries – a 25-fold difference. These findings highlight the importance of studies which not only estimate the burden of disease, but also provide quantitative guidance on the impact of potential strategies to improve global health.
“We found that a scale-up of traditional imaging and treatment modalities and quality-of-care improvements could achieve 70 percent of total potential gains, with substantial impact in LMICs,” explained Dr. Hricak. “This approach provides a more feasible pathway to improving breast cancer survival in these settings even without the benefits of future investments in targeted therapy and advanced imaging.”
Among individual treatment modalities, scaling up access to surgery alone was estimated to yield the largest survival gains globally and scaling up CT alone would have the largest global impact among imaging modalities. Scaling up a package of traditional modalities (surgery, chemotherapy, radiotherapy, ultrasound, and x-ray) could improve global 5-year net survival to 75.6 percent, with survival in low-income countries improving from 3.5 percent to 28.6 percent. Adding concurrent improvements in quality of care could further improve global 5-year net survival to 78.2 percent, with a substantial impact in low-income countries, improving net survival to 55.3 percent. Comprehensive scale-up of access to all modalities and improvements in quality of care could improve global 5-year net survival to 82.3 percent.
The researchers found that a survival gap still exists by country income group after comprehensive scale-up due to a worse stage at diagnosis in low-income regions. Dr. Norton explains, “early diagnosis of breast cancer has a major impact on curability, which is why we are so concerned about a drop in screening worldwide as a consequence of the COVID-19 pandemic. This novel but verified modeling approach has shown us that enormous gains could result from scaling up the availability of established quality treatments, but also from investments in cancer prevention and early detection. We hope that these findings will provide guidance to policymakers everywhere as they seek to improve the health of their populations. Moreover, this work underscores the value of comprehensive analysis based on real-world experience in projecting the impact of healthcare interventions.”
