MIAMI BEACH, Fla--Radiation therapy may not be necessary after the removal of ductal carcinoma in situ (DCIS), Gordon F. Schwartz, MD, said at the 14th International Breast Cancer Conference. In his experience, only 3% of DCIS patients who received breast-conserving surgery alone later experienced invasive breast cancer.
Although his data lack the rigorous scientific standard of a randomized, clinical trial, Dr. Schwartz, professor of surgery, Jefferson Medical College, Philadelphia, believes that his findings still offer encouragement for "the very motivated patient who wants to conserve her breast and does not want to undergo radiation."
The study included 194 breast procedures to eliminate DCIS. After five years of surveillance, cancer returned in 28 women (14.4%), but almost all of the recurrences (23) were also DCIS.
In addition, most of the DCIS recurrences showed up within three years of the first treatment, suggesting, he said, that they might really have been part of the original tumor that was left behind in the first surgery.
More than 180,000 cases of breast cancer will be diagnosed this year, and one fourth--45,000--will be DCIS. At one time, the treatment of choice for DCIS was mastectomy, but, more recently, surgeons have been using breast-conserving lumpectomy. Treatment of DCIS has been controversial, Dr. Schwartz said, "because we do not know the natural history of DCIS."
Mammography has led to the earlier detection of nonpalpable, subclinical DCIS, Dr. Schwartz said. Concurrently, the inevitable progression of DCIS to invasive carcinoma has been questioned, and the traditional use of mastectomy has been challenged for these minute areas of disease.
In his presentation, Dr. Schwartz asked, rhetorically, "Is it reasonable to treat these subclinical areas of malignant cells, which have not yet demonstrated the ability to invade or metastasize--the definition of DCIS--by local excision alone without requiring attention to the whole breast or axilla?" He believes that such an approach is reasonable in carefully selected patients. The women in the Jefferson College study were selected by the surgical team after considering various risk factors.
Dr. Schwartz noted that many surgeons and oncologists seem more concerned with the morphology or architecture of the DCIS in making a decision about further treatment than in the biology of the cancer.
He believes that more important information to quantify parameters of aggressiveness--proliferation markers, steroid receptors, and the like--should be collected on all patients with DCIS to see if other, more precise, predictors of recurrence can be identified.
The ultimate objective, he reiterated, is to identify subsets of patients with subclinical DCIS who are unlikely to suffer recurrence of disease after local excision alone, sparing them from either mastectomy or irradiation.