Background: The incidence of ductal carcinoma in situ (DCIS) of the breast has dramatically increased over the past 25 years. Most cases initially were treated with mastectomy; however, breast-conserving therapy (with or without radiation) has become more common. Although breast-conserving therapy provides a better cosmetic result, it is associated with a higher rate of local recurrence, distant spread, and cancer-related mortality. Lee and colleagues studied outcomes in women treated for DCIS between 1972 and 2005 and compared the outcomes of mastectomy versus breast-conserving treatment strategies.

The Study: They identified 1,236 patients with DCIS. The mean follow-up time was 72 months. In general, women who had small lesions (up to 40 mm) with clear margins (at least 1 mm) were advised to follow breast-conserving treatment strategies; however, other patients were advised to undergo mastectomy, usually with immediate reconstruction. The study outcomes included recurrence with invasive disease, distant recurrence, and breast cancer–specific mortality.

Results: Overall, 150 women had local recurrences: 87 were noninvasive and 63 were invasive. The calculated overall 12-year local recurrence probability was 19 percent, the probability of local invasive recurrence was 8 percent, and breast-cancer specific mortality was 1 percent.

For the 430 women treated with mastectomy, the 12-year probability of local invasive recurrence was 0.5 percent and the probability of death from breast cancer was 0.8 percent. For 806 women treated with breast-conserving strategies, the 12-year probability of local invasive recurrence was 12 percent and the probability of death from breast cancer was 1 percent. The probability of local invasive recurrence was identical for patients who received radiation and local excision and for those who only had excision. Conversely, patients who were treated with radiation had higher rates of distant disease (2 versus 0.4 percent). For the 150 women who developed local recurrence, the probability of distant disease was 7 percent and the probability of death from breast cancer was 6 percent. No patient with non-invasive local recurrence developed distant disease or died from breast cancer. In the 63 women who developed local invasive recurrence, the probability of distant disease was 15 percent, and the probability of death from breast cancer was 12 percent.

Conclusion: The authors emphasize that patients with DCIS have a good prognosis regardless of treatment strategy. They also note that treatments have evolved considerably since their data collection, and the current prognosis may be better than reported. Although breast preservation treatment strategies were associated with somewhat worse outcomes in this series, many of the differences were not statistically significant and there was no survival advantage following mastectomy. The authors encourage physicians to remind their patients that the breast cancer survival rates for DCIS are 99 percent or more.