Women who have ductal carcinoma in situ ( DCIS ) are very likely to develop invasive breast cancer if left untreated.
The risk extends over more than forty years

Invasive ductal carcinoma, unlike ductal carcinoma in situ, invades the fatty tissue of the breast. This invasive carcinoma has the potential to metastasize and spread through the bloodstream or lymphatic system.
It is important to detect and treat invasive ductal carcinoma before it has had time to metastasize and spread to other organs.

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 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.

Researchers, led by Melinda E. Sanders and David L. Page of the Vanderbilt University Medical Center in Nashville, 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.

They were later recognized to be small DCIS lesions on subsequent examination in the 1970s when DCIS and ADH were better defined.

The study has showed low-grade DCIS evolves gradually to invasive breast cancer in the same breast, with the greatest risk for transformation to invasive breast cancer 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 invasive breast cancers 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 invasive breast cancer diagnosis.

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

Source: Cancer, 2005


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