423P - Marginalization and factors associated with early mortality among patients diagnosed with de novo metastatic breast cancer in Ontario, Canada

Background

In Ontario, breast cancer affects 1 in 9 women and 2000 women die from breast cancer annually. Early death from breast cancer is uncommon and may be influenced by factors such as biology, age, marginalization, socioeconomic status, and rurality. Our objective was to investigate factors associated with early mortality from advanced de novo metastatic breast cancer in a publicly funded health care system.

Methods

We used linked healthcare administrative data from 2010-2019 to determine the frequency of early mortality, defined as death within 6 months of cancer diagnosis, from de novo metastatic breast cancer. A multivariable logistic regression model was used to determine which patient, cancer, and provider characteristics may be associated with early mortality. The Ontario Marginalization Index, a census and geographically based tool evaluating economic, ethno-racial, age-based and social marginalization, was used.

Results

We identified 4,004 patients with de novo metastatic breast cancer, of whom 22.9% (N=918) experienced early mortality (death within 6 months). Multivariable regression revealed that advanced age and a high marginalization index score (HMIS) were significantly associated with early mortality. [HMIS odd ratio vs low marginalization index score (LMIS) (OR)=1.48, 95% confidence interval (CI)=1.17-1.88, p-value=0.001]. Registration with a family physician was associated with significant decreased risk of early mortality (OR=0.74, 95%CI=0.62-0.89, p-value<0.001). There was variability in early mortality across geographic regions of the province and rurality did not affect early mortality until patients received treatment. Treatment with chemotherapy alone (typically used in triple-negative breast cancer) had higher odds of early mortality. Provider characteristics and acuity of the cancer center were not associated with early mortality.

Conclusions

The results of this study suggest that factors such as marginalization, access to a family physician, and geography play a role in early mortality from breast cancer in the setting of a publicly funded health care system. Improving access to a family physician may help to reduce early breast cancer mortality.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Patient donor.

Disclosure

J. Raphael: Financial Interests, Personal, Advisory Role: Eli Lilly, Merck; Financial Interests, Personal, Advisory Board: Novartis, Roche. M. Lock: Financial Interests, Personal, Advisory Role: Bayer, Abbvie, Tolmar, Eisai, Ferring, Tersera. A. Eisen: Financial Interests, Personal, Project Lead: Ontario Health Breast Cancer Disease Site ; Financial Interests, Personal, Research Funding: RNA diagnostics. P. Blanchette: Financial Interests, Personal, Advisory Role: Canada’s Drug and Health Technology Agency. All other authors have declared no conflicts of interest.