Helical tomotherapy for bilateral breast cancer: Clinical experience

We report our initial clinical experience with using Helical tomotherapy to irradiate the bilateral breasts/chest-wall and regional nodes. Methods: The records of patients who received bilateral irradiation of the breast/chest-wall and regional nodes with tomotherapy were retrospectively reviewed. Clinical outcomes for tumor and normal tissues were assessed. Results: From August 2011 to January 2016, nine women were identified; median age 52 years (range 37-74), mean follow up was 10.3 months (range 0.3-34). In two patients, tomotherapy represented re-irradiation to one side. All received regional nodal irradiation. The average lung V20 was 29% (range 25-35), average lung V5 was 66% (range 51-75). Average heart mean dose was 20 Gy (range 13-28). Normal tissue outcomes: Acute toxicity during radiation included dysphagia (5/9), fatigue (4/9), nausea and weight loss (1/9) and skin desquamation (9/9). Two patients were lost to long follow-up and one patient recently completed treatment. Longer-term toxicity included: pneumonitis (1/6), elevated liver function tests (1/6) and sternal osteonecrosis (1/6; in patient with prior sternal surgery). Conclusions: Despite the small numbers of patients and relatively short follow-up, significant clinical toxicities were observed. Given the rarity of this situation and relatively high rate of complications in this small series, considerable care should be taken in minimizing dose to normal structures. Longer follow up with larger numbers of patients will be needed to establish safe dosimetric parameters for bilateral breasts/chest wall and nodal irradiation with tomotherapy.