Percentage of local recurrence following treatment for breast cancer is not a suitable performance indicator

OBJECTIVE: To describe the percentage of local recurrences within 5 years after surgery for breast cancer as a performance indicator for Dutch hospitals. DESIGN: Descriptive, cohort study. METHOD: All women diagnosed with a primary invasive breast cancer in 2003 for which they underwent curatively intended surgical treatment (with or without radiotherapy), were selected from the Netherlands Cancer Registry (NCR). NCR registration clerks collected additional information on recurrences within 5 years after initial diagnosis following standardized protocol. Percentages of local recurrences per hospital were estimated using Kaplan Meier analysis and were presented in forest plots and funnel plots. RESULTS: In 2003, 9898 women diagnosed with primary breast cancer were curatively treated in one of the 99 Dutch hospitals. 266 patients experienced local recurrences within 5 years. The 5-year percentage of local recurrences was 3.03% (95% CI: 2.69-3.41). Following breast conserving surgery the 5-year percentage of local recurrence was 2.63% (95% CI: 2.21-3.12), and following mastectomy 3.50% (95% CI: 2.97-4.13). Stratification by hospital shows large variation in recurrence rates (0-17%). However, the number of patients treated in most hospitals is too small to provide reliable estimates. CONCLUSION: The percentage of local recurrences following surgical treatment for breast cancer in the Netherlands was lower than the accepted standard of 5% within 5 years. Statements on differences in quality of care between hospitals cannot be made on the basis of these data, on account of the low average recurrence rate and the small number of cases per hospital.