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Although neoadjuvant chemoradiotherapy (CTRT) followed by surgery is preferred, definitive CTRT is also one of the recommended management strategies for squamous cell carcinoma of middle oesophagus (ME-SCC). Definitive CTRT protocols are evolving. We aimed to prospectively evaluate the acute toxicity and early clinical outcome in ME-SCC treated with definitive CTRT using volumetric modulated arc therapy (VMAT) with simultaneous integrated boost (SIB).

We enrolled 15 patients of histologically proven ME-SCC in a prospective interventional study (IEC 54/19) between December 2019 to December 2020. 60 Gray at 2 Gray per fraction was delivered to the gross disease and elective nodes were irradiated to 48 Gray at 1.6 Gray per fraction, 5 fractions per week with SIB-VMAT. Concurrent cisplatin 75mg/m2 (on day 1 and day 21) and 5-Fluorouracil 1000 mg/m2 (day 1 to 4 and day 21 to 25) were delivered. Acute toxicities are reported with Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.

Median age was 52 years (32- 68 years) and 60% were female. Median Karnofsky performance scale was 80. Stage distribution was II:III in  9:6 patients respectively. 13 patients (86.6%) completed CTRT as per protocol. Due to treatment related toxicity, one patient received 50Gy with 2 cycles of concurrent chemotherapy and one patient succumbed after 5 fractions of radiotherapy due to unknown reason.

Median V95 for planning target volume (PTV) for primary and elective nodes was 98.42±1.48% and 99.43±0.82% respectively. Median mean dose received by both lungs was 18.64±2.81 and median lung volume receiving 20Gy (V20) was 33.16±5.23% of the total lung volume. Median Dmax of cord and median mean dose to heart were 42.5±1.15Gy and 27.17±6.05Gy respectively. 

Median follow-up was 13 months (5-19 months). 10 (67%) patients had complete response till the time of last follow-up, 1 patient had recurrence of disease after six months of completion of treatment, 3 patients had residual disease at the time of first follow-up. Acute toxicity profiles observed were grade 3 in 3 patients (20%), grade 4 (dysphagia) in 1 patient (6.6%). None had grade 5 toxicity. The highest grade of various Grade 1-3 toxicities assessed are enumerated in Table 1. At the end of 3 months only 1 patient with no radiological evidence of disease, had grade 3 dysphagia.

In patients of ME-SCC treated with definitive CTRT, SIB-VMAT yields a favourable dosimetry with sparing of organs at risk. The treatment regimen is well tolerated with acceptable acute toxicity profile and excellent early clinical outcome with complete response in 2/3rd of patients.