Selective use of whole breast radiotherapy after breast conserving surgery for invasive breast cancer and DCIS

Abstract

Background: Radiotherapy following breast conservation is routine in the treatment of invasive breast cancer and is commonly used in ductal carcinoma in situ to decrease local recurrence. However, adjuvant breast radiotherapy has significant short and longer-term side effects and consumes substantial health care resources. We aimed to review the randomised controlled trials and attempted to identify clinico-pathological factors and molecular markers associated with the risk of local recurrence.

Methods: A literature search using the Medline and Ovid databases between 1965 and 2011 was conducted using the terms 'breast conservation' and radiotherapy, and radiotherapy and DCIS. Only papers with randomised clinical trials published in English in adult were included. Only Level 2 evidence and above was included.

Results: Three meta-analyses and 17 randomised controlled trials have been published in invasive disease and one meta-analysis and four randomised controlled trials for DCIS. Overall, adjuvant radiotherapy provides a 15.7% decrease in local recurrence and 3.8% decrease in 15-year risk of breast cancer death. The key clinico-pathological factors, which enable stratification into high, intermediate or low risk groups include age, oestrogen receptor positivity, use of tamoxifen and extent of surgery. Absolute reductions in 15-year risk of breast cancer death in these three prediction categories are 7.8%, 1.1%, and 0.1% respectively Adjuvant radiotherapy provides a 60% risk reduction in local recurrence in DCIS with no impact on distal metastases or overall survival. Size, pathological subtype and margins are major risk factors for local recurrence in DCIS.

Conclusions: Adjuvant radiotherapy consistently decreases local recurrence across all subtypes of invasive and in-situ disease. While it has a survival advantage in those with invasive disease, this is not seen with DCIS and is minimal in invasive disease where the risk of local recurrence is low. This group includes women over 70 with node negative, ER positive tumours<2 cm.

Keywords: Adjuvant radiotherapy; Breast conserving surgery; DCIS; Invasive breast cancer.