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Adjuvant chest wall radiotherapy (RT) is routinely offered to all patients (pts) with T3 and T4 disease.  Historically, radiotherapy was not offered to all pts with high risk T1 and T2 disease and those with N1 disease.  This study analyses the incidence and pattern of local recurrence (LR) in a retrospective cohort of pts post mastectomy in a single institution over a three-year period.

The Edinburgh Cancer Centre departmental database was accessed to identify all pts managed surgically, in a single institution, with a mastectomy following a diagnosis of invasive breast cancer from 1st January 2012 to 31st December 2014.   The search identified 443 eligible patients.

The median age of pts at time of surgery was 58 years (range: 34-84).  At a median follow up of 90 months, 23 pts (5%) had developed a local recurrence. 35% (n=8) were under 50 years old at the time of recurrence (median age 60, range 36-88). Median duration between diagnosis and recurrence was 20 months with 4 pts having local recurrence within 1 year of diagnosis.

At original diagnosis of invasive cancer, 11/23 pts had triple negative disease. 19/23 pts had received chemotherapy (8 neoadjuvant, 9 adjuvant) and the 10/23 ER positive pts all received adjuvant endocrine treatment.

15/23 pts were assessed for post mastectomy RT due to high-risk pathological features (4 or more nodes after axillary clearance (n=3), involved nodes + high risk features (G3, ER negative, HER2 positive) (n=5), T3 or T4 disease (n=6), involved margin (n=1)). Only 11 patients received adjuvant RT, 4 patients did not due to co morbidities (n=2), patient choice (n=1), and recurrence (n=1) prior to starting adjuvant RT.

The overall LR rate following mastectomy is low at 5% with median 8 year follow up. Those with LR had higher risk disease at diagnosis, which, despite chemotherapy, recurred mostly within 2 years after treatment. Adjuvant chest wall RT following mastectomy improves local control (1) and is now offered in our centre to patients with T3 and T4 disease at presentation, but also to patients with T1 and T2 disease with 1-3 nodes positive at the time of axillary node clearance in presence of a high-risk feature e.g. grade 3, triple negative, HER 2 positive cancers to further decrease LR.  

References 

(1)    Hypofractionated versus conventional fractionated postmastectomy radiotherapy for patients with high-risk breast cancer: a randomised, non-inferiority, open-label, phase 3 trial. Lancet Oncol. 2019; 20: 352-360