Modern Rotational Radiation Techniques with Volumetric Modulated Arc Therapy or Helical Tomotherapy for Optimal Sparing of the Lung and Heart in Left-Breast Cancer Radiotherapy Plus Regional Nodal Irradiation: A Comparative Dosimetric Analysis

Background: For advanced breast cancer with lymph node involvement, adjuvant radiotherapy (RT) with regional nodal irradiation (RNI) has been indicated to reduce cancer recurrence and mortality. However, an extensive RT volume is associated with normal organ exposure, which increases the toxicity and affects patient outcomes. Modern arc RT techniques can improve normal organ sparing compared with conventional techniques. The aim of this study was to explore the optimal technique for left-breast RT with RNI. Methods: We retrospectively reviewed patients receiving RT with RNI for left-breast cancer. We used modern arc RT techniques with either volumetric-modulated arc therapy (VMAT) or helical tomotherapy (HT) with a novel block technique, and compared differences in dosimetry parameters between the two groups. Subgroup analysis of RNI with or without internal mammary node (IMN) volume was also performed. Results: A total of 108 eligible patients were enrolled between 2017 and 2020, of whom 70 received VMAT and 38 received HT. The median RT dose was 55 Gy. No significant differences were found regarding the surgery, RT dose, number of fractions, target volume, and RNI volume between the VMAT and HT groups. VMAT reduced the heart mean dose more than HT (3.82 vs. 5.13 Gy, p < 0.001), as well as the cardiac parameters of V5-V20, whole-lung mean dose, lung parameters of V5-V20, and contralateral-breast and esophagus mean dose. In the subgroup analysis of RNI with IMNs, the advantage of VMAT persisted in protecting the heart, lung, contralateral breast, and esophagus. HT was beneficial for lowering the thyroid mean dose. For RNI without IMN, VMAT improved the low-dose exposure of the heart and lung, but HT was similar to VMAT in terms of heart, whole-lung, and contralateral-breast mean dose. Conclusions: For patients with left-breast cancer receiving adjuvant RT with RNI, VMAT reduced the exposure dose to the heart, lung, contralateral breast, and esophagus compared with HT. VMAT was superior to HT in terms of normal organ sparing in the patients who underwent RNI with IMN irradiation. Considering the reduction in normal organ exposure and potential toxicity, VMAT is the optimal technique for patients receiving RNI when deep inspiration breath-hold is not available.

Long Term Arm and Shoulder Toxicities in Breast Cancer Patients Receiving Hypofractionated Radiation Therapy

Aim: The purpose of this study is to evaluate the late toxicities in hypo fractionated radiation schedule in breast cancer patients with regional nodal irradiation (RNI), limited to axilla and supraclavicular regions. Late effects on arm and shoulder were noted as follows: skin edema (lymphedema), restricted shoulder movements (brachial plexus injury) and localised pain.Material and Methods: In this study we randomly enrolled 100 breast cancer post mastectomy cases in the year 2018. All cases were previously asymptomatic after surgery. They were prospectively treated with hypo fractionated local and regional nodal irradiation by 2.67 gray / fraction dose, total 15 fractions (total dose-40 gray). Evaluation was done at 12 months after completion of radiation therapy. Assessment was done by RTOG, LENT- SOMA scales. Results: Significant lymphedema was observed in 17 (17%) cases. Restricted arm mobility was seen in 14 (14%) of patients. Pain (moderate/severe) in arm and shoulder was most commonly seen, in 25 (25%) cases. Conclusions: As hypo fractionated regimes in breast cancer treatment have become new standard; its late term effects are significant and comparable to other conventional radiation therapy regimes. These studies need further and longer duration of evaluation.