BOX 2-4
Treatment for DCIS

Women with biopsy-proven DCIS are typically treated surgically with either mastectomy or BCS (also known as lumpectomy). Along with BCS, treatment often includes adjuvant radiotherapy (RT) and in some cases, hormone therapy (tamoxifen).22,24 Although BCS is recommended for the majority of DCIS cases, mastectomy remains the treatment of choice for many women in the United States. Mastectomy is specifically indicated for women with two or more primary tumors in the breast or with diffuse malignant-appearing microcalcifications, and also when persistent positive tumor margins remain after reasonable surgical attempts.26,71,114 Mastectomy may also be more appropriate in cases of extensive DCIS that can be removed with only a small negative margin, particularly in small-breasted patients. Total mastectomy is associated with very low rates of local recurrence (1.4 percent) and breast cancer-specific mortality (0.6 percent).69

Treatment guidelines recommend BCS plus RT for localized DCIS (that is, for single, nondiffuse loci) less than or equal to 4 cm, meanwhile acknowledging the inherent difficulty of accurately measuring DCIS lesions.71 Younger women tend to have a greater risk of local recurrence after BCS plus RT, which results at least in part from the biological characteristics of disease in younger women.105

Although no randomized trials have yet been published, retrospective studies indicate that total mastectomy improves disease-free survival of DCIS as compared with BCS plus RT, but there is no evidence to suggest the superiority of mastectomy over BCS plus RT in terms of overall and breast-cancer-specific survival.3,69,89

There have been some reports of low recurrence rates following BCS alone for small-volume lesions with clear margins, but the maximum size of DCIS for which RT could be safely omitted is unknown.69,71 Three recent randomized controlled trials demonstrated that BCS plus RT significantly reduces the incidence of local recurrence of DCIS.30,31,38,47,69 Most nonrandomized trials reported findings consistent with these randomized trials and showed that adjuvant RT after BCS significantly decreased the incidence of ipsilateral (same side) breast tumor recurrence.13,52,69,89,101 Randomized trials show that recurrence with lumpectomy alone is approximately 30 percent at 10 years and reduced by half with radiotherapy. Despite the higher rates of recurrence, there is no difference in the mortality rates for lumpectomy alone versus lumpectomy with RT; rates for both are in the range of mortality for mastectomy, which is about 2 percent. Fifty percent of recurrences are DCIS and the other 50 percent are invasive breast cancer. Although not considered a mandatory part of treatment for DCIS, tamoxifen therapy appears to benefit some patients.32,69,114

grade tumors. DCIS is now recognized to be very heterogeneous is its clinical behavior.46

Although there is an element of overdiagnosis of DCIS in breast cancer screening, this appears to be relatively small. For example, a recent study reported that the average incidence of nonprogressive DCIS is about 1 in



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