Dosimetric analysis and clinical outcomes of brachial plexus as an organ‑at‑risk in head‑and‑neck cancer patients treated with intensity‑modulated radiotherapy

Prakash, Bhanu B and Yathiraj, Prahlad H and Sharan, Krishna T and Singh, Anshul and Reddy, Anusha S and Chandraguthi, Srinidhi Gururajarao and Subramanian, Ramya Bala and Nagesh, Jyothi and Nair, Sarath S and Fernandes, Donald J and Vidyasagar, Sudha (2019) Dosimetric analysis and clinical outcomes of brachial plexus as an organ‑at‑risk in head‑and‑neck cancer patients treated with intensity‑modulated radiotherapy. Journal of Cancer Research and Therapeutics, 15 (3). pp. 522-527. ISSN 0973-1482

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Abstract

Objectives: To document the dose received by brachial plexus (BP) in patients treated with intensity-modulated radiotherapy (IMRT) for head-and-neck squamous cell carcinoma (HNSCC) and report the incidence of brachial plexopathy. Methods: Newly diagnosed patients of HNSCC treated with radical or adjuvant IMRT were included in this retrospective study. No dosimetric constraints were applied for BP maximum dose equivalent dose (EQD2 α/β = 3). Patients with minimum 6‑month follow‑up were included and patients with suspicion of plexopathy were evaluated further. Results: Sixty‑seven patients were eligible and 127 BP were analyzed. The mean BP maximum dose (BPmax) was 62.4 Gy (+6.9), while mean BP volume was 28.1 cc (+4.1). Proportion of patients receiving BPmax >66 and >70 Gy were 34.7% and 14.2%. The mean BPmax for T4 tumors was significantly higher than T1 tumors (65 vs. 57.5 Gy, P = 0.005) but when adjusted for N‑category, T‑category was not independently significant in accounting for BPmax >66 or >70 Gy. Mean BPmax for N0 versus N2+ was 59.8 versus 65.6 Gy (P = 0.0001) and N1 versus N2+ was 61.6 versus 65.6 Gy (P = 0.018). After adjusting for T‑category, patients with N2+ had a mean 4.2 Gy higher BPmax than N0‑N1 (P = 0.0001). Stage III–IV patients had a mean six Gy higher BPmax doses than Stage I–II disease (P = 0.0001). With a median follow‑up of 28 months (interquartile range 16–42), no patient had brachial plexopathy. Conclusion: Clinically significant plexopathy was not seen in spite of majority having over 2‑years follow‑up and a third of patients having dose above the recommended tolerance. Only nodal category independently influenced dose to the brachial plexii.

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