Compliance with consensus recommendations for systemic therapy is associated with improved survival of women with node-negative breast cancer

Abstract

Purpose: The impact of consensus recommendations for systemic therapy on outcome of disease is unclear. We evaluated if compliance with guidelines for systemic adjuvant treatment is associated with improved survival of women with node-negative breast cancer.

Patients and methods: The study population included women diagnosed with invasive node-negative breast cancer in Québec, Canada, in 1988 to 1989, 1991 to 1992, and 1993 to 1994. Information was collected by chart review, linkage with administrative databases, and queries to attending physicians. Guidelines from the 1992 St Gallen conference were used as standard of care. Survival was estimated by Kaplan-Meier and Cox proportional hazards analyses.

Results: Among 1,541 women, 358 died before December 1999. Median follow-up was 6.8 years. Seven-year event-free and overall survivals were 66% and 81%, respectively. Survival was 88%, 84%, and 74% in women at minimal, moderate, or high risk of recurrence. Virtually all women at minimal risk were treated according to the consensus (98.4% of 370). In comparison, adjusted hazard ratios of death were 1.0 (95% CI, 0.6 to 1.7) and 2.3 (95% CI, 1.3 to 4.0) among women at moderate risk treated according to the consensus or not, respectively. Among women at high risk, adjusted hazard ratios of death were 2.0 (95% CI, 1.4 to 2.8) and 2.7 (95% CI, 1.9 to 3.9), respectively. Both risk category (P <.0005) and compliance with guidelines (P <.0005) were independent significant predictors of survival.

Conclusion: Treatment according to consensus recommendations is associated with improved survival of women with breast cancer in the community. Promoting the adoption of guidelines for treatment is an effective strategy for disease control.