The relationship between microscopic margins of resection and the risk of local recurrence in patients with breast cancer treated with breast-conserving surgery and radiation therapy

Abstract

Background. The relationships among the involvement of tumor at the final margins of resection, the presence of an extensive intraductal component (EIC), and the risk of local recurrence are important considerations in patients treated with conservative surgery and radiation therapy for early stage breast cancer but have not been defined adequately. Methods. Between 1982 and 1985, 885 patients were treated for clinical Stage I or II invasive breast cancer. The study population was limited to 181 patients with an infiltrating ductal carcinoma who received a radiation dose to the surgical site of 60 Gy or greater, whose final microscopic margins of resection were evaluable, and who had at least 5 years of follow‐up. A positive margin was defined as tumor present at the inked margin of resection, a close margin as tumor within 1 mm of the inked margin, and a negative margin as no tumor within 1 mm of the inked margin. A focally positive margin was defined as tumor at the margin in three or fewer low‐power fields. In 157 patients (87%), the tumor was evaluable for the presence or absence of an EIC. The median follow‐up was 86 months. Results. In 12 of 181 patients (7%), a recurrence developed at or near the primary site (true recurrence/marginal miss [TR/MM]) within 5 years. The 5‐year rate of TR/MM (with 95% confidence intervals) among patients with negative, close, focally positive, and more than focally positive margins was 0% (0‐4%), 4% (0‐20%), 6% (1‐17%) and 21% (10‐37%), respectively. Patients with positive margins also were more likely to have a distant failure within 5 years (14%, 8%, 25%, and 32% in the four groups, respectively). However, patients with positive margins more often had positive axillary lymph nodes than patients with negative or close margins (59% vs. 38%, P < 0.02). The 5‐year rate of TR/MM was 20% for patients with an EIC‐positive tumor and 7% for patients with an EIC‐negative tumor. However, among the 127 patients with an EIC‐negative tumor, the 5‐year rate of TR/MM was less than 10% in all margin groups. Among the 30 patients with an EIC‐positive tumor, the 5‐year rate of TR/MM was 0% when margins were negative or close but 50% when margins were more than focally positive. Conclusions. These results provide support for the use of breast‐conserving surgery and breast irradiation in all patients with uninvolved margins, whether the tumor is EIC‐positive or EIC‐negative. This study suggests that breast‐conserving therapy (including a radiation boost to the primary site) also may be a reasonable option for some patients with an EIC‐negative tumor and margin involvement.

Standard for Breast Conservation Therapy in the Management of Invasive Breast Carcinoma

“…87,88 Most recently, the EORTC has reported the favorable impact of boost on local failure rates. 88 Several considerations may be involved in the decision to use a boost: histological studies show that residual cancer following resection of the primary cancer usually is in the vicinity of the primary site; 89 recurrences following treatment usually are seen at or near the primary site; 90 and boost treatment can be delivered without significant morbidity. 91 Although boost irradiation generally is used, the precise indications for its use are not well defined.…”

Needle core biopsy characteristics identify patients at risk of compromised margins in breast conservation surgery

“…Certainly, other authors have shown that DCIS in core biopsies is a marker of extensive intraductal component, 9,10 a previous relative contraindication for breast conservation, [20][21][22] which had been considered to increase the risk of compromised margins. 23,24 In this study, a DCIS component on core biopsy was associated with extratumoural DCIS on excision specimen. This relationship appeared particularly pronounced in patients who had a high percentage of DCIS on core biopsy, with 57% of patients with extratumoural DCIS having 450% DCIS component on core biopsy.…”

Improving local control with breast‐conserving therapy

“…11,[42][43][44] Consistent with these reports, in the study reported here, the presence of negative margins was associated with improved IBTR-free survival in both univariate and multivariate analyses. Therefore, our multidisciplinary emphasis on improving margin status may have contributed to the declining IBTR rates in our study.…”