Variations in treatment of ductal carcinoma in situ of the breast: A population-based study in the East Netherlands

AIMS: Differences in treatment of ductal carcinoma in situ (DCIS) of the breast were analysed for a geographically defined population in the East Netherlands. METHODS: Data from the Cancer Registry of the Comprehensive Cancer Centre East Netherlands were analysed for treatment of DCIS in the period between January 1989 and December 2003. The study population consisted of 800 female patients with a first diagnosis of DCIS of whom 798 underwent surgical treatment. The distribution of tumour characteristics and treatment were compared for several time periods. RESULTS: Surgical treatment was specified for 648 patients: 51% underwent breast-conserving surgery. The proportion of patients treated with breast-conserving surgery increased: 43% in the period 1994-1998 and 55 after 1999 (p<0.01). An axillary staging procedure was performed in 149 patients (19%), of whom 2 (1%) had tumour-involved lymph nodes. Of patients treated with breast-conserving surgery, 133 (40%) received radiation therapy: 7% in the period 1994-1998 compared to 62% after 1999 (p<0.01). Patients (60%) of 50 years or younger were treated with mastectomy compared to 44% in patients aged 50-69 years and 50% in patients of 70 years and older (p<0.01). The rate in use of radiation therapy after breast-conserving surgery was comparable to both age groups. CONCLUSION: This study shows variability in the treatment of DCIS in a geographically defined region. Approximately half of all patients were treated with mastectomy and 19% underwent an axillary staging procedure; this may represent aggressive, unwarranted treatment. In contrast, 38% of patients treated with breast-conserving surgery were not treated with radiation therapy after 1999, which may represent under-treatment.