Early outcomes of breast cancer patients treated with post-mastectomy uniform scanning proton therapy. (March 2019)

• Record Type: Journal Article
• Authors: Luo, Leo; Cuaron, John; Braunstein, Lior; Gillespie, Erin; Kahn, Atif; McCormick, Beryl; Mah, Dennis; Chon, Brian; Tsai, Henry; Powell, Simon; Cahlon, Oren
• Is Part Of: Radiotherapy and oncology. Volume 132(2019)
• Page Start: 250
• Page End: 256
• Publication Date: 2019-03
• Subjects: Breast cancer -- Postmastectomy radiation -- Proton therapy -- Clinical outcome -- Toxicity; Oncology -- Periodicals; Radiotherapy -- Periodicals; Tumors -- Periodicals; Medical Oncology -- Periodicals; Neoplasms -- radiotherapy -- Periodicals; Radiotherapy -- Periodicals; Radiothérapie -- Périodiques; Cancérologie -- Périodiques; Tumeurs -- Périodiques; Electronic journals; 616.9940642
• DOI: 10.1016/j.radonc.2018.10.002
• Languages: English
• ISSNs: 0167-8140

Abstract

Highlights: This study represents the longest follow-up of patients who received post-mastectomy proton radiation with median follow-up of 35 months. Proton postmastectomy radiation achieves equivalent and excellent clinical outcomes compared to photon radiation with over 95% loco-regional control rate and overall survival rate. Proton radiation is able to significantly reduce the dose to heart and lung, but the clinical correlation is unclear due to limited follow-up period. Abstract: Background: Postmastectomy proton radiotherapy improves normal tissue sparing in comparison to photon-based approaches. Several studies have reported dosimetry comparison and tolerable acute toxicity profile with limited follow-up. We report our institutional experience of postmastectomy proton radiation including clinical efficacy and toxicities. Methods: From December 2013 to February 2015, 42 consecutive patients who received mastectomy for non-metastatic breast cancer were treated with adjuvant chest wall and regional nodal proton therapy at a single proton center. 3D conformal uniform scanning with en face matching fields was used. Results: The median follow-up among patients was 35 months (range 1–55 months). There was one local failure, zero regional nodal failure, and six distant failures. The 3-year rate of locoregional disease-free survival was 96.3%, metastasis-free survival was 84.1%, and overall survival was 97.2%. The only local failure event occurred on the chest wall within the radiation field, approximately 2.5 years after the completion of radiation. Skin dermatitis, fatigue, and esophagitis were the most common acute toxicity. All patients developed grade 1 or 2 acute skin toxicity and there was no grade 3 or 4 acute skin toxicity. Proton radiation is able to achieve excellent target coverage with median PTV V95 over 95% and heart sparing with median mean heart dose less than 1 Gy (RBE). Conclusion: With close to three years of median follow-up, post-mastectomy proton radiation has shown excellent locoregional control rates and favorable toxicity profile. Long-term adverse effect of heart-sparing radiation will require longer follow-up time and randomized clinical trials.