Ductal Carcinoma In Situ (Intraductal Carcinoma)

Ductal carcinoma in situ (DCIS) in a noninvasive form of breast cancer in which tumor cells are confined to the ductolobular system and surrounded by an intact basement membrane. If left untreated, DCIS has a substantial risk of evolving into invasive ductal carcinoma of the breast. Currently in the United States at least 12% to 15% of newly diagnosed breast cancer cases annually are DCIS. There was a marked increase in DCIS incidence beginning in the early 1980s, correlating with the widespread use of mammography for screening. Average annual increases in rates between 1973 and 1983 and between 1983 and 1992 changed from 5.2% to 18.1% among women aged 50 years or older, compared to 0.3% to 12.0% among women aged 30 to 39 years and 0.4% to 17.4% among women aged 40 to 49 years. Because DCIS cannot cause serious morbidity in and of itself, the major issue in the management of DCIS is the risk of progression to invasive breast cancer. Although many women with DCIS will ultimately develop invasive disease, not all untreated DCIS will go on to become invasive breast cancer in a woman’s lifetime. This issue is particularly important when considering the treatment of DCIS in an older woman with a potentially limited life expectancy.

In the past, mastectomy was the standard treatment for DCIS. In light of the success of breast-conserving surgery with radiation for invasive disease, there has been great interest in breast-conserving therapy with or without breast irradiation for the treatment of DCIS.

NSABP protocol B-17 demonstrated that overall local recurrence rate for patients treated with excision alone was 27% at 8 years compared to 12% for those patients treated with excision plus radiotherapy. Despite the improvement in local recurrence, there was no evidence that survival was compromised in the group that did not receive radiation. The use of tamoxifen as adjuvant therapy for DCIS has also been evaluated. In NSABP protocol B-24, treatment with tamoxifen after breast-conserving therapy yielded a further reduction in breast cancer events (8.2% versus 13.4%; p = 0.0009) including recurrence of noninvasive disease and development of invasive disease. Once again, despite the decreased risk of breast recurrence, there was no impact of tamoxifen on survival. Several recent studies have revealed that older women with DCIS have a significantly decreased risk of recurrence than younger women after local therapy, perhaps due to increased surgical margins obtained among older women. Although radiation and tamoxifen are both considerations for the treatment of an older woman with DCIS, the option of wide excision alone remains a reasonable choice, particularly for patients with low- to intermediate-grade DCIS with clear margins. Although tamoxifen is a consideration, the absence of a survival benefit and the increased risk of complications (thromboembolic disease and endometrial cancer) with tamoxifen mandate careful consideration of the risk and benefits of tamoxifen in an older woman with DCIS.

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Revision date: July 9, 2011
Last revised: by Tatiana Kuznetsova, D.M.D.