Overdiagnosis and overtreatment of breast cancer: rates of ductal carcinoma in situ: a US perspective

Abstract

The incidence of breast ductal carcinoma in situ (DCIS) in the USA exceeds that of other countries. This cannot be explained entirely by the frequency of mammographic screening in the USA and may result from differences in the interpretation of mammograms and/or the frequency with which biopsies are obtained. Although the percentage of DCIS patients treated with mastectomy has decreased, the absolute number is unchanged and the use of lumpectomy with whole-breast radiotherapy has increased in inverse proportion to the decrease in mastectomy. Treatment of DCIS with tamoxifen is still limited.

Figure 1

Treatment of DCIS in the USA, 1973 to 2002. Source: SEER (Surveillance, Epidemiology, and End Results). These data were compiled at the Northern California Cancer Center from Surveillance, Epidemiology, and End Results (SEER) Program SEER*Stat Database: Incidence – SEER 9 Regs Public-Use, Nov 2004 Sub (1973–2002), National Cancer Institute, DCCPS, Surveillance Research Program, Cancer Statistics Branch, released April 2005, based on the November 2004 submission, which is a sum of data from population-based cancer registries at nine distinct geographic sites collected for the period 1 January 1973 to 31 December 2002. The query was limited to women with non-invasive in situ breast cancer, excluding lobular carcinoma in situ. Rates were age-adjusted with US census data from 2000. Patients with any evidence of microinvasive disease would be considered by SEER to have invasive breast cancer and thus were excluded from the study. For this time interval 45,597 cases met this definition, 189 cases in 1973 and 3,335 in 2002. The distribution of patients by type of surgery or use of radiotherapy is based on the patients for whom there is a specific indication that the therapy was given or not given. The denominator for analyses of other therapies is based on the total number of patients diagnosed. The number of patients included in the calculation for 'lumpectomy' includes those who had a single surgical procedure and those who had an initial surgical procedure plus a re-excision. A few patients in the latter category might have been counted twice if the two procedures were performed in different years. XRT, radiotherapy.

Figure 2

Recommended management guidelines for DCIS developed by and subscribed to by American breast cancer specialists. The scheme shown here is based primarily on guidelines developed by the National Comprehensive Cancer Network (NCCN), a coalition of 19 academic cancer centers in the USA. The American College of Surgeons Commission on Cancer, the American Society of Clinical Oncologists, and the American Society for Therapeutic Radiation Oncologists do not at present endorse any specific guidelines for the management of DCIS but refer to those of the NCCN (Clinical Practice Guidelines in Oncology, Breast Cancer, V.2.2005: Ductal Carcinoma in Situ, DCIS-1 to 3) in their literature (or where information is provided on the Internet, link to the NCCN site [21]). ALND, axillary lymph node dissection; ER, estrogen receptor; XRT, radiotherapy.