Long-Term Pulmonary Outcomes of a Feasibility Study of Inverse-Planned, Multibeam Intensity-Modulated Radiation Therapy (IMRT) in Node-Positive Breast Cancer Patients Receiving Regional Nodal Irradiation.

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Long-Term Pulmonary Outcomes of a Feasibility Study of Inverse-Planned, Multibeam Intensity-Modulated Radiation Therapy (IMRT) in Node-Positive Breast Cancer Patients Receiving Regional Nodal Irradiation.

Int J Radiat Oncol Biol Phys. 2018 Nov 30;:

Authors: Ho AY, Ballangrud A, Li G, Gupta GP, McCormick B, Gewanter R, Gelblum D, Zinovoy M, Mueller B, Mychalczak B, Dutta P, Borofsky K, Parhar P, Reyngold M, Braunstein L, Chawla M, Krause K, Freeman N, Siu CT, Cost Z, Arnold BB, Zhang Z, Powell SN

Abstract
BACKGROUND: Multi-beam IMRT enhances the therapeutic index by increasing the dosimetric coverage of the targeted tumor tissues while minimizing volumes of adjacent organs receiving high doses of RT. The tradeoff is that a greater volume of lung is exposed to low doses of RT, raising concern about the risk of radiation pneumonitis (RP).
METHODS: Between 7/2010-1/2013, patients with node-positive breast cancer received inverse-planned, multibeam IMRT to the breast/chest wall and regional nodes including the internal mammary nodes (IMN). The primary endpoint was feasibility, predefined by dosimetric treatment planning criteria. Secondary endpoints included the incidence of > grade 3 RP and changes in pulmonary function measured by CTCAE v3.0 scales, pulmonary function tests (PFTs) and community acquired pneumonia (CAP) questionnaires, obtained at baseline and at 6 months post-IMRT. Clinical follow-up was q6 months up to 5 years.
RESULTS: Median follow-up was 53.4 months (0-82 months). Of 113 patients enrolled, 104 completed follow-up procedures. Coverage of the breast/chest wall and IMN was comprehensive (median 48.1 Gy and 48.9 Gy, respectively. Median volume of lung receiving high dose (V20Gy) and low dose (V5) was 29% and 100%, respectively. The overall rate of respiratory toxicities was 10.6% (11/104) including 1 grade 3 RP event (.96%). No differences were found in PFT or CAP scores following IMRT. The 5-year rate of locoregional recurrence-free, disease-free and overall survival was 93.2%, 63.6%, and 80.3%, respectively.
CONCLUSIONS: Multi-beam IMRT in breast cancer patients receiving RNI was dosimetrically feasible, based on early treatment planning criteria. Despite the large volume of lung receiving low dose RT, the incidence of grade 3 RP was remarkably low, justifying inverse-planned IMRT as a treatment modality for high-risk breast cancer patients in whom conventional RT techniques prove inadequate.

PMID: 30508620 [PubMed - as supplied by publisher]

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