Role of radiotherapy boost in women with ductal carcinoma in situ: a single-center experience in a series of 389 patients.

BACKGROUND

The use of adjuvant radiotherapy in ductal carcinoma in situ is accepted by most radiation oncologists worldwide; the role of a boost on the tumor bed is however more controversial.

MATERIALS AND METHODS

We reviewed our Institute experience in DCIS treatment, focusing on main prognostic factors and impact of radiation boost on local relapse. A total of 389 patients treated between 1990 and 2007 were retrospectively analyzed. All patients received adjuvant radiotherapy after breast-conserving surgery for a median dose of 50 Gy; 190 patients (48.8%) received and additional radiation boost on the tumor bed.

RESULTS

At a mean follow up of 7.7 years, we recorded 26 local recurrence (6.7%). Concerning local relapse-free survival, at Cox regression univariate analyses <1 mm surgical margins (p < 0.0001) and young age (p = 0.01) emerged as significant unfavorable prognostic factors. At multivariate analysis Cox regression model, surgical margins (p < 0.001) and radiation boost (p = 0.014) resulted as the significant independent predictors of recurrence.

CONCLUSIONS

Our experience showed the negative prognostic impact of surgical margins <1 mm and the protective role of radiation boost on LR rate. Anyway, results from ongoing prospective Phase III studies are strongly necessary to better identify high-risk DCIS patients.