Abstract
Background/Aims
Ductal carcinoma in situ (DCIS) makes up approximately 25% of all breast cancer diagnoses and is considered to be a precursor to invasive cancer. Most DCIS diagnoses will not progress to invasive cancer, but reliable prognostic and predictive markers to guide treatment have not been established. Considerable debate exists about how to best treat DCIS, and many have expressed concern that DCIS is over-diagnosed and over-treated. This study examined patterns of DCIS incidence and treatment across six regions of Kaiser Permanente (KP).
Methods
Women aged ≥ 18 years of age diagnosed with DCIS between 2000 and 2010 were identified from tumor registries at each region using distributed code. Annual age-adjusted incidence rates of DCIS were estimated overall and by region and were standardized to the 2000 US population. The annual incidence of DCIS was also estimated for women aged ≥ 45 years and stratified on hormone replacement therapy status at DCIS diagnosis. Demographic characteristics and variation in first course of therapy were compared.
Results
Across six KP regions, overall age-adjusted incidence was 35.2/100,000 in 2000, increased to a high of 47.2/100,000 in 2007, and then decreased to 42.6/100,000 in 2010. Age-adjusted incidence rates for women on estrogen plus progestin hormone therapy prior to diagnosis were higher than for women on estrogen only or no hormone therapy. The most common first course therapy was breast conserving surgery plus radiation (38%); however, we observed different treatment patterns across regions. These patterns will be explored further in additional analyses that will include examining variation in treatment patterns by age, year of diagnosis, and histopathologic characteristics such as hormone receptor status and tumor grade.
Conclusions
Although age-adjusted incidence rates from six KP regions were consistent over time, we observed differences in treatment patterns. Differences in patient mix, tumor characteristics, patient, or physician preferences may have contributed to the variation in treatment patterns. These results may be of clinical use in determining factors associated with DCIS diagnosis and in understanding and evaluating regional treatment differences.
Keywords: Ductal carcinoma in situ, Breast cancer treatment