Untreated low-grade ductal carcinoma in situ poses long-term risk

05/04/05

Ductal carcinoma in situ (DCIS) of the breast develops into invasive breast cancer (IBC) in approximately 50 percent of women if left untreated, with the risk extending over more than forty years, according to a new study appearing in the June 15, 2005 issue of CANCER (http://www.interscience.wiley.com/cancer-newsroom), a peer-reviewed journal of the American Cancer Society. The study, a four-decade long follow-up of women with low-grade DCIS treated by biopsy alone from 1950-1968, reveals the natural history of this poorly understood breast cancer and supports curative treatment by surgical excision.

In the decades prior to mammographic screening, DCIS--presented as breast lump--was recognized microscopically by its high-grade features similar to invasive cancer, and represented only a small subset of all breast cancers. Small low-grade DCIS lesions simply were not recognized and were thus diagnosed as benign. Over the next 20-30 years, as criteria for diagnosis of DCIS were redefined, DCIS has gradually been recognized as spectrum of disease varying considerably in grade and extent. However, important differences in the clinical course of low- and high-grade disease have not always been appreciated. In addition, the distinction between low-grade and DCIS and the histologically similar but lesser lesions of atypical ductal hyperplasia (ADH) is critical as ADH lesions pose only small malignancy risk and predict risk to both breasts rather than regional risk. With the advent of mammography, DCIS is now identified earlier and is the largest growing subset of breast cancers. Understanding the natural history of low-grade DCIS can provide insight into current and future treatment strategies.

Led by Melinda E. Sanders, M.D. and David L. Page, M.D. of the Vanderbilt University Medical Center in Nashville, researchers followed the course of 28 women treated by biopsy only in the 1950s and 1960s for what were identified at the time as benign lesions. However, they were later recognized to be small DCIS lesions on subsequent examination in the 1970s when DCIS and ADH were better defined. Follow-up investigations of this group of women were previously published in 1982 and 1995.

The study showed low-grade DCIS evolves gradually to IBC in the same breast, with the greatest risk for transformation to IBC within the first 15 years of diagnosis. Forty-six years after the first woman was biopsied, 11 of the 28 women had developed invasive breast cancer. All IBCs were found in the same breast and quadrant as the original DCIS biopsy site. Eight were diagnosed within 12 years of the DCIS biopsy. Three were diagnosed 23 to 42 years after the DCIS biopsy. Five of these 11 women developed metastatic disease as late as 29 years after the original DCIS biopsy and died within seven years of IBC diagnosis.

The authors conclude, "Even low-grade DCIS, left without further treatment, predicts for a regional risk and will eventuate in invasive carcinoma in the same site in the same breast in 30 percent of cases within 15 years."

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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