Nuclear Medicine & Radiation Therapy

40/42Gy in 13 Fractions: A Safe Dose for the Brachial Plexus

Abstract

Gabriela Studer, David Norbert Stocker, Karl Ferdinand Loewenich and Christoph Glanzmann

Aims: The use of hypo fractionated irradiation of the whole breast has regained much interest after the publication of the results of large randomized trials showing equivalent results as using standard fractionation (START A and B, randomized START pilot trials, Canadian trial). Due to the relatively low numbers of patients treated with hypofractionation to the supraclavicular ±axillary (S/A) region, the question of the brachial plexus tolerance continues to be discussed. Aim of this work was to assess the high grade long term tolerance of the brachial plexus in our patients treated with 13x 3.3Gy to the S/A lymph nodes, in order to contribute to the question of plexus tolerance.
Materials and Methods: Between 1967 and 1977, 130 female breast cancer patients underwent postoperative hypo fractionated radiotherapy at the University Hospital Zurich. The most used schedule was 13x 3.3Gy midline dose, 3x/week (n=124) to the S/A region applied by equally rated antero-posterior/postero-anterior portals. A first assessment of the cohort was performed in 1994, which has been updated in December 2013. Patients with a follow up period <5 years or loco-regional disease have been excluded in 1994 (n=4, all without plexopathy). Pre-radiation surgery consisted of radical mastectomy in 98% and breast conserving operation in 2% of all patients, including axillary dissection. Pathological stage was pT1/2/3/4 in 28/58/10/4%; with pN0/pN+ in 57/43%. The mean/median follow up time of the cohort was 28.1/26.6 years (range, 7.2-44.8).
Results: One grade 2 brachial plexus neuropathy was observed.
Conclusion: The long term follow up in our patients corroborates the hypothesis of a total mid plane dose to the S/A region between 40-42Gy in 13 fractions being comparably safe as 25x 2.0Gy to 50Gy.