No abstract

IntroductionA comparative study was conducted comparing the difference between (1) conformal radiotherapy (CRT) to the whole breast with sequential boost excision cavity plans and (2) intensity-modulated radiation therapy (IMRT) to the whole breast with simultaneously integrated boost to the excision cavity. The computed tomography (CT) data sets of 25 breast cancer patients were used and the results analysed to determine if either planning method produced superior plans.MethodsCT data sets from 25 past breast cancer patients were planned using (1) CRT prescribed to 50 Gy in 25 fractions (Fx) to the whole-breast planning target volume (PTV) and 10 Gy in 5Fx to the excision cavity and (2) IMRT prescribed to 60 Gy in 25Fx, with 60 Gy delivered to the excision cavity PTV and 50 Gy delivered to the whole-breast PTV, treated simultaneously. In total, 50 plans were created, with each plan evaluated by PTV coverage using conformity indices, plan maximum dose, lung dose, and heart maximum dose for patients with left-side lesions.ResultsCRT plans delivered the lowest plan maximum doses in 56% of cases (average CRT = 6314.34 cGy, IMRT = 6371.52 cGy). They also delivered the lowest mean lung dose in 68% of cases (average CRT = 1206.64 cGy, IMRT = 1288.37 cGy) and V20 in 88% of cases (average CRT = 20.03%, IMRT = 21.73%) and V30 doses in 92% of cases (average CRT = 16.82%, IMRT = 17.97%). IMRT created more conformal plans, using both conformity index and conformation number, in every instance, and lower heart maximum doses in 78.6% of cases (average CRT = 5295.26 cGy, IMRT = 5209.87 cGy).ConclusionIMRT plans produced superior dose conformity and shorter treatment duration, but a slightly higher planning maximum and increased lung doses. IMRT plans are also faster to treat on a daily basis, with shorter fractionation.

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.