Aim: The aim of this study was to determine dosimetric factors, such as mean dose and oesophageal length, which may influence the incidence and severity of oesophagitis in breast cancer patients receiving radiotherapy to the supraclavicular nodes.
Methods: This was a single-arm prospective observational study. Toxicity grading was undertaken twice weekly to determine the onset of grade 2 oesophagitis in consecutive patients prescribed IMRT to the breast or chest wall and supraclavicular fossa (SCF) nodes. Recorded variables included mean and maximum doses to the oesophagus, oesophageal length and pharynx length within the treatment area. Multivariate logistic regression and Fishers' exact test were used with a 0.05 significance level to compare the onset of grade 2 oesophagitis with these variables.
Results: A total of 77 patients were included in the study. Twenty-four (31%) patients reported grade 2 oesophagitis. There was a higher incidence of grade 2 oesophagitis in patients receiving a mean oesophageal dose of ≥31 Gy compared to those receiving < 31 Gy (18/24 versus 6/24, respectively, P = 0.025). There was a significant difference in the onset of grade 2 toxicity in patients who had ≥ 1 cm of pharynx included in SCF fields compared with those with <1 cm (15/24 versus 9/24, respectively, P = 0.0116). The odds ratios for developing grade 2 oesophagitis were 3.2 (95% CI = 1.05-9.62, P = 0.04) for a mean dose of ≥31 Gy and 3.4 (95% CI = 1.19-9.5, P = 0.022) for ≥1 cm of pharynx in the SCF field.
Conclusion: By limiting the mean dose to the irradiated oesophagus to <31 Gy during the planning process and ensuring that <1 cm of pharynx is included in the radiation field, oesophageal toxicity may be minimised.
Keywords: breast cancer; intensity modulated; oesophagitis; radiotherapy.
© 2019 The Royal Australian and New Zealand College of Radiologists.