Adherence to treatment guidelines and survival in triple-negative breast cancer: a retrospective multi-center cohort study with 9156 patients

Background: Triple-negative breast cancer (TNBC) remains a challenging topic for clinical oncologists. This study sought to evaluate TNBC versus other breast cancer subtypes with respect to survival parameters. We evaluated possible differences in survival in TNBC by age and by the extent to which evidence-based treatment guidelines were adhered. Methods: This German retrospective multi-center cohort study included 9156 patients with primary breast cancer recruited from 1992 to 2008. Results: The rates of guideline adherence are significantly lower in TNBC compared to non-TNBC subtypes. These lower rates of guideline adherence can be observed in all age groups and are most pronounced in the >65 subgroup [<50 (20.9% vs. 42.0%), 50-64 (25.1% vs. 51.1%), and >65 (38.4% vs. 74.6%)]. In TNBC patients of all age groups, disease-free survival and overall survival were associated with an improvement by 100% guideline-adherent adjuvant treatment compared to non-adherence. Furthermore, TNBC patients of all ages had similar outcome parameters if 100% guideline-adherent adjuvant treatment was applied. Conclusion: The rates of guideline-adherent treatment were significantly lower in TNBC, even though guideline adherence was strongly associated with improved survival. In the case of 100% guideline-adherent treatment, no difference in survival was observed over all the age groups examined, even in the group of >65-year-old TNBC patients.