Aim: There are only limited studies available in literature that discuss methods to reduce the oesophageal dose and acute oesophagitis during breast cancer radiotherapy. The aim of this study is to compare dose volumetric parameters of oesophagus in radiation treatment of breast with and without oesophagus delineation. Methods: Treatment plans of 44 patients, who underwent chest wall and supraclavicular fossa irradiation, were selected for the study. Oesophagus was later delineated and treatment replanned using three-dimensional conformal radiotherapy (3DCRT) considering oesophagus as an organ at risk (OAR). The dose prescribed was 40 Gy/15 fractions to the planning target volume (PTV). Dose volumetric parameters of oesophagus such as maximum dose (Dmax), mean dose (Dmean), the percentage of oesophagus volume receiving ≥15Gy (V15), ≥25Gy(V25), ≥33Gy(V33) and ipsilateral lung volume parameters V4, V8 and V16 were compared with already executed plans in which oesophagus was not delineated. Results: Contouring the oesophagus as an OAR as a part of the radiotherapy treatment for Carcinoma Breast resulted in statistically significant reduction in dose to the oesophagus. No statistically significant change was found in the ipsilateral lung volume parameters. No compromise in plan quality was required as evident from the statistically non-significant differences in Homogeneity index and Conformity index. Findings: 3DCRT planning with oesophagus delineation can be considered as a method to reduce oesophageal dose and the acute oesophageal toxicity during radiotherapy for carcinoma breast.
BACKGROUND Acute esophagitis (AE) is a common toxicity seen in patients undergoing radiotherapy (RT) for breast cancer, which can affect their quality of life. Thus, majority of our patients receiving hypo fractionated dose of 40 Gy in 15 fractions were having AE. We conducted this study to evaluate the dosimetric parameters of oesophagus and correlate with published literature. METHODS Treatment plans of 80 post mastectomy patients who underwent radiotherapy for carcinoma of breast (Ca breast) with a dose of 40 Gy in 15 fractions to the chest wall along with supra clavicular fossa (SCF) were selected. Out of these, 44 patients (22 each in right and left side) were simulated in neck straight position and 36 in neck tilted position (18 each in right and left side). The oesophageal volume was contoured in already executed plans from the inferior border of cricoid cartilage to the inferior border of the SCF planning target volume (PTV). No plan modification was done after contouring the oesophagus. Dosimetric parameters like the maximum dose (Dmax) and mean dose (Dmean) to oesophagus, volume of oesophagus receiving ≥ 5 Gy (V5), ≥ 10 Gy (V10), ≥ 15 Gy (V15), ≥ 20 Gy (V20), ≥ 25 Gy (V25), ≥ 30 Gy (V30) were derived from dose volume histogram (DVH) data and analysed. RESULTS Dmean in straight neck group irrespective of side was 18.57 (± 7.30) Gy and in tilted neck 22.94 (± 9.53,) Gy, P = 0.023. Subgroup analysis shows Dmean was significantly high in patients with left sided disease than those with right sided disease (24.10 vs. 13.03, P = 0.00) in the straight neck cases. In the neck tilted group there was a nonsignificant increase in Dmean in left sided cases (25.36 vs. 20.53, P = 0.13). CONCLUSIONS Evaluation of oesophageal dosimetric parameters in hypofractionated dose showed that DmeanEQD2 was within the values of published studies in conventional fractionation. KEYWORDS Oesophageal Dosimetric Parameters, Breast Cancer
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