Is standard treatment of ductal carcinoma in situ of the breast (DCIS) overtreatment? A retrospective multicenter study of 450 patients.

Abstract

Purpose: The current standard treatment for all cases of ductal carcinoma in situ of the breast (DCIS) is full surgical excision with or without postoperative radiotherapy (RT). Is this overtreatment? This study is aimed at appraising retrospectively the outcomes of the therapeutic approaches adopted in DCIS-affected patients and to define whether the standard treatment can be tailored on the basis of immunohistochemistry and surrogate molecular classification.
Methods: 450 patients treated for DCIS between 2006 and 2016 at the Umberto I Hospital of Turin and at the Candiolo Cancer Institute – FPO, IRCCS were enrolled in this retrospective multicenter study. Correlation between treatment received and local recurrence (LR) was analyzed.
Results: The median follow-up was 81 months and the LR rate was 8.22%. Patients treated with breast-conserving surgery (BCS) alone showed a fourfold greater risk of relapsing when compared with those treated with mastectomy (OR 4.61, 1.74–12.20). No significant risk difference was observed between BCS+RT and mastectomy. Sentinel lymph node biopsy was performed in 56.5% of patients treated with BCS and in 98.9% of those treated with mastectomy: the positivity rate was 8.8% for microinvasive DCIS, and 0.4% for pure DCIS. The risk of relapsing was more than halved in patients with hormone receptor-positive DCIS treated with tamoxifen (OR 0.38, 0.19–0.74). The St. Gallen 2013 surrogate molecular subtype definitions were used to categorize the molecular patterns of 105 patients with pure DCIS; this revealed a non-significant trend for triple negative DCIS to relapse more, and sooner, than luminal DCIS.
Conclusions: Current treatment for DCIS allows to LR rates to be kept low. Molecular classification of DCIS appears to be of little help in the everyday management of the disease.

PDF