60. Factors detremining local control in patients (Pts) with locally advanced breast cancer (Labc) managed with radiotherapy (RT) as the primary locoregional treatment
Abstract
Introduction
RT plays an important role in the management of LABC, yet clinical outcomes still remain far from satisfactory. The aim of this study was to evaluate retrospectively factors determining local control in a large series of consecutive LABC pts managed with RT as the primary locoregional treatment.
Material and methods
The records of 261 primarily inoperable LABC pts treated between 1991 and 1997 at two institutions: Medical University of Gdansk, Poland and Velindre NHS Trust, Cardiff, UK were analysed. All pts received megavoltage RT to the breast with two tangential fields, and the adjacent lymph node areas were irradiated using customised fields. Due to a large scale of RT doses and fractionation schedules, normalised total dose (NTD) was calculated for all patients using a linear quadratic model. In 241 pts RT constituted the only local treatment and the remaining 20 pts were subsequently subjected to mastectomy. Most pts received chemotherapy and/or endocrine therapy prior or after RT.
Results
Within the median follow-up of 37 months, locoregional recurrence occurred in 95 of 251 evaluable pts (38%). Three-year and five-year locoregional-free survival rates were 59% and 48%, respectively. At multivariate analysis of variables predicting the risk of locoregional relapse, inflammatory carcinoma (p<0.01; RR 2.1), T4 disease (p<0.01; RR 2.9) and involvement of supraclavicular lymph nodes (p<0.01; RR 2.4) were the most significant clinical factors, whereas response to RT (p<0.01; RR 1.2) and NTD (p<0.01; RR 0.7) were the most important therapeutic factors. Increasing the total dose to the tumour by 10 Gy was associated with 30% reduction of local relapse.
Conclusions
Due to large heterogeneity of LABC pts, judicious tailoring of RT, particularly in terms of dose prescribing, is essential to increase the chance of locoregional cure.