0
0
VANCOUVER, British Columbia — Organized mammography screening programs significantly improve the 10-year net survival rates for Canadian women aged 40-49 years at no or moderate risk for breast cancer, according to findings presented at the 2024 Family Medicine Forum.
The research challenges draft guidelines from the Canadian Task Force on Preventive Health Care, which recommend against routine mammography screening for women in this age group.
Significant Survival Benefits
Dr. Anna N. Wilkinson, a family physician and cancer care lead at the University of Ottawa, explained that her team analyzed data from the Canadian Cancer Registry, focusing on women aged 40-49 and 50-59 diagnosed with breast cancer between 2002 and 2007. By comparing jurisdictions with and without organized screening programs, they identified a clear survival advantage for women aged 40-49 in areas offering mammography.
The study found a 10-year net survival rate of 84.8% in regions with screening programs, compared to 82.9% in regions without. This 1.9-percentage-point improvement was particularly notable among women aged 45-49, where the difference increased to 2.6 percentage points.
“Net survival is critical because it isolates the impact of the specific cancer in question,” Wilkinson said. Her analysis revealed that breast cancer was the primary cause of mortality in 90.7% of deaths among women diagnosed in their 40s.
The Debate Over Overdiagnosis
Wilkinson also challenged concerns about overdiagnosis, the detection of indolent cancers that may not lead to death or require treatment. She argued that earlier detection generally leads to less invasive treatments and better outcomes, including reduced time off work and lower healthcare costs.
“One of the biggest benefits of screening women in their 40s is the ability to diagnose cancer at an earlier stage, which means fewer intensive therapies and less long-term morbidity,” she emphasized.
Modeling Supports Caution
However, the Canadian Task Force on Preventive Health Care, led by Dr. Guylène Thériault, defends its draft guidelines. The task force reviewed data from 165 studies, including randomized trials and observational research, and used modeling to assess the impact of mammography for women aged 40-49 over a decade.
Their model suggested that for every 1,000 women screened, 368 would experience false positives, 55 would undergo biopsies, and 19 would be diagnosed with breast cancer. Of those, two would be treated for cancers that would not cause harm (overdiagnosis), while one or two deaths would be prevented.
Without screening, the model predicted 17 breast cancer cases per 1,000 women, with two resulting in death, but no overdiagnosis.
Thériault emphasized the importance of shared decision-making, urging family physicians to discuss these trade-offs with patients.
Future Implications
Wilkinson argued that the study’s findings could inform updates to screening guidelines, underscoring the survival benefits for women aged 40-49. “Our data suggest that screening programs in this age group lead to better outcomes without significantly increasing diagnoses,” she concluded.
The study was supported by the University of Ottawa’s Department of Family Medicine. Wilkinson disclosed consulting work with Thrive Health, while Thériault reported no relevant financial relationships.
