The Value of Ipsilateral Breast Tumor Recurrence as a Quality Indicator: Hospital Variation in the Netherlands

All Dutch hospitals are obliged to report their 5-year ipsilateral breast tumor recurrence (IBTR) rate after breast cancer surgery. Experts decided that these rates should not exceed 5 %. This study determined the value of IBTR as an indicator to compare quality of care between hospitals.

All patients with breast cancer (pT1-3, any N, M0) who underwent surgery in 1 of 92 Dutch hospitals from 2003 to 2006 were identified in the Netherlands Cancer Registry. Data of recurrence was retrieved from hospital records. Five-year IBTR rates for breast-conserving surgery (BCS) and mastectomy were calculated by using the Kaplan-Meier method. Hospital variation was presented in funnel plots. Multivariate analysis was used to assess hospital characteristics associated with IBTR rates.

A total of 40,892 breast cancer patients were included. The overall 5-year IBTR rate was 2.85 % (95 % confidence interval 2.68-3.03) and was significantly lower for BCS than for mastectomy (2.38 vs. 3.45 %, p < 0.001). IBTR rates decreased over time in both groups. Rates varied between 0.77 and 5.70 % between hospitals. When random variation is taken into account, only extremely high IBTR rates can be detected as deviant from the target value of 5 %. Adjusting for tumor and patient characteristics, analyses showed that a higher volume of mastectomies is associated with lower IBTR rates.

Our population-based findings show that IBTR rates in the Netherlands are low and have improved over time. The 5-year IBTR rate as an indicator for quality of care of individual hospitals is of limited value.