Primary care access tied to fewer early deaths in metastatic breast cancer

Clinical takeaway: Patients with de novo metastatic breast cancer who lack a regular primary care physician or live in marginalized communities appear more likely to die within 6 months of diagnosis, highlighting the importance of timely access to primary care, screening, and oncology services.

Although survival has improved for metastatic breast cancer, some patients still die soon after diagnosis. Limited Canadian data have examined how social factors and healthcare access contribute to these early deaths in patients whose cancer is already metastatic when first detected.

In a population-based Ontario study, researchers analyzed 4,004 adults diagnosed with de novo metastatic breast cancer between 2010 and 2019. Overall, 918 patients, or 22.9%, died within 6 months of diagnosis, including 6.5% who died within 1 month.

Older age, greater comorbidity burden, and higher levels of housing and material deprivation were associated with a greater likelihood of early death. Patients living in the most marginalized communities had roughly 20% to 30% higher odds of dying within 6 months than those in the least marginalized communities.

Access to primary care appeared protective. Patients registered with a primary care physician had 26% lower odds of early death than those without one. They were also more likely to have undergone mammography within the previous 2 years, with screening rates of nearly 60% versus 42% among those lacking a primary care physician.

Among the 2,390 patients who received systemic therapy, higher marginalization remained linked to worse outcomes. Rural and semi-urban residents experienced approximately 76% and 55% higher odds of early death, respectively, than urban residents, suggesting ongoing barriers to cancer care after treatment begins.

The authors also found substantial geographic variation across Ontario and noted that patients with triple-negative breast cancer had particularly high rates of early death.

“Optimizing cancer prevention and mammography screening in marginalized communities may reduce the likelihood of presenting with metastatic disease,” the authors concluded. “Our findings highlight the need for better primary care access.”

Source: Thomas P, et al. (2026 Oct 19) CMAJ. Factors associated with early death from de novo metastatic breast cancer in Ontario, Canada