Surgery for Pure DCIS

Historically, DCIS comprised about 3% of breast cancers, and most cases were large palpable tumors. Recently, an increasing portion of patients present with impalpable DCIS. Up to one-third of breast cancers found on screening mammography are DCIS. Consequently, 20-25% of breast cancers seen in a population where screening is widespread will be DCIS.

In the past, the standard treatment for DCIS was total mastectomy. The local recurrence and mortality rates have been uniformly low after mastectomy, and mastectomy remains the gold standard against which lesser treatments are compared. Today, total mastectomy remains the standard treatment for extensive or multifocal DCIS. Despite the paucity of prospective trials for DCIS, the treatment has altered as the pattern of disease has changed. Most surgery for DCIS now comprises wide excision with or without radiation therapy.

The major problem with BCT for DCIS is the risk of local recurrence; specifically, up to 50% of recurrences are invasive. Various factors contribute to the risk of recurrence. Important tumor-related factors are the size and histologic features of the tumor. Positive surgical margins are also associated with recurrence. Young patients may have higher recurrence rates, although it is not certain that age is an independent risk factor.

The NSABP-B17 trial compared wide excision alone to wide excision with postoperative adjuvant radiation therapy in patients with DCIS who were treated conservatively. This trial reported that the addition of adjuvant radiation therapy reduced the incidence of overall recurrence by about 50% and the incidence of invasive recurrence by about two-thirds.

There does not appear to be a survival advantage associated with adjuvant radiation therapy. In the US, most patients with DCIS are treated with surgery and radiation, while in Britain, the lack of survival effect has been frequently interpreted as meaning that radiation is not mandatory.

Attempts have been made to predict the risk of local recurrence in order to help patients and clinicians decide between treatments. The Van Nuyes Prognostic Index is perhaps the best known such attempt. This system rates the grade of DCIS, the size of the tumor, and the excision margin to produce an overall score.

Tumors with a low score may be appropriate for wide excision alone, those with an intermediate score may be appropriate for wide excision with radiation therapy, and those with a high score are at high risk of recurrence, even with radiation therapy, and so might be better treated with mastectomy. The major obstacle to the widespread adoption of the Van Nuyes Prognostic Index lies in the fact that it is very difficult to accurately assess the size of the tumor and to quantify the precise size of the margin of excision.

Patrick I. Borgen and Bruce Mann
Breast conservation therapy for invasive carcinoma of the breast. Current Problems in Surgery 1995; 33:189-256.