Do variations in treatment of ductal carcinoma in situ affect outcomes

Ductal carcinoma in situ (DCIS) is a noninvasive form of breast cancer with a distinct disease pathology and natural history compared to invasive breast cancer. Its incidence has increased since the widespread use of screening mammography. Earlier detection of the disease and changing treatment patterns for early invasive breast cancer have led to treatment changes for DCIS without an understanding of the natural history of DCIS. The lack of information on the natural history of DCIS has led to doubts about the best way to treat it and has given rise to substantial variations in treatment patterns for the disease.;The overall objective of this project is to examine the effects of geographic and temporal variation in the treatment of women diagnosed with unilateral DCIS. The study will test two major hypotheses: (1) there is statistically significant geographic and temporal variation in the treatment of women with DCIS, both in type of surgery (mastectomy or breast-conserving surgery) and use of radiotherapy; and (2) variation in treatment of DCIS' has consequences for rates of recurrence of DCIS and development of subsequent; invasive breast cancer.;This research is based on data from the Surveillance, Epidemiology and End Results (SEER) program linked with Medicare claims data from 1991--1998, the Dartmouth Atlas of Health Care in the United States, and US Census data. The longitudinal, observational study uses econometric methods to advance the field of measuring geographic variation and to analyze the impact of treatment choice, region effects, and socioeconomic factors on patient outcomes for women ages 65 and older.;Geographic location and year of diagnosis are significant predictors of treatment choice for DCIS, indicating geographic and temporal variation in treatment patterns. The results of the outcomes analysis strongly suggest that treatment of DCIS with mastectomy or breast-conserving surgery (BCS) with radiotherapy are much better than with BCS alone. Disease-free survival 6 years after diagnosis and treatment by mastectomy or BCS with radiotherapy is 96% compared to 86% for BCS alone. Treatment with mastectomy or BCS with radiotherapy produces superior outcomes compared to BCS alone which is the worst in terms of disease-free survival.