Most cases of DCIS are detectable only by mammography, and the large increases in DCIS incidence rates since 1982 are a direct result of better mammography screening practices. Although invasive breast cancer incidence rates have remained level since 1988, DCIS incidence rates have continued to increase. This, however, reflects a shift in the stage of the disease at diagnosis toward earlier, more curable cancers rather than a true increase in occurrence. It is sometimes difficult to distinguish between DCIS and atypical hyperplasia, a benign breast condition consisting of more breast cells than is normal, some with atypical features. A second-opinion of the biopsy may therefore be appropriate.
Accurate diagnosis is important because of the significant differences in treatment options.
There is disagreement among breast cancer experts about whether mastectomy is an appropriate treatment for DCIS that is localized to one area of the breast and that could be removed by a lumpectomy. Some feel breast removal is not justified for a diagnosis that may never lead to breast cancer. An ongoing national study being conducted by the National Cancer Institute is seeking to learn whether lumpectomy followed by radiation therapy and tamoxifen is more effective than lumpectomy followed only by radiation. Results are not yet available. In the News A number of promising studies are resulting in a better understanding of ductal carcinoma in situ and how best to treat the disease.