Remarks given during a session of the ASCO Breast Cancer Symposium titled Ductal Carcinoma in Situ Debate: Treatment vs. Observation
Dr. Kuerer comments: There has been a marked increase ductal carcinoma in situ (DCIS) in what is being called overdiagnosis, and this is leading to concerns of overtreatment, which has been in the news now for several years. We have more than 60,000 cases of DCIS diagnosed per year in the United States. We’re trying to prevent invasive breast cancer and distant metastases. The problem is identifying which patients will go on to develop invasive disease. That’s really unknown.
At M.D. Anderson, looking at 10-year follow-up of 2,449 patients, the rate of developing distant metastases was 0.1%. The problem with this is that no prominent variables were associated with the development of invasive metastatic disease. Overall, we are doing a good job at preventing death from breast cancer when we treat DCIS, with less than 1% of patients dying of breast cancer (Ann. Surg. Onc. 2011;18:2873-8).
Dr. Henry M. Kuerer
Dr. Shelley E. Hwang and her group very elegantly started exploring preoperative systemic therapy as a way to get a clue about which patients might be safely observed alone (that is, a core biopsy diagnosis of DCIS and then just follow-up without surgery or other treatments). At M.D. Anderson, we studied whether or not we could eradicate DCIS in patients with human epidermal growth factor receptor 2 (HER2) overexpression by treatment with trastuzumab prior to surgery, under the hypothesis that if we could eradicate the DCIS, we might eventually use this drug potentially to prevent HER2-positive invasive breast cancers. We saw very dramatic responses in their immune response with antibody-dependent cellular cytotoxicity mediated by natural killer cells, which is exciting, but there were no histopathologic changes. The most important finding was that 42% of our patients who we thought only had DCIS actually had occult invasive breast cancer (Cancer 2011;117:39-47). This is concerning because without surgery, we may be missing or leaving untreated invasive breast cancers in some patients.