Assessment of pulmonary function tests in carcinoma esophagus patients treated with three-dimensional conformal radiation therapy versus intensity-modulated radiation therapy

ABSTRACT Background: Three-dimensional conformal radiation therapy (3DCRT) provided enhancement in target delineation for the avoidance of normal structures, but considerable doses are still received by normal tissues. Intensity-modulated radiation therapy (IMRT) manipulates the photon beams of radiation to conform to the shape of a tumor and deliver precise radiation doses to the tumor, while sparing normal tissues. The distinct dosimetric advantages of IMRT have been proven by various studies. Materials and Methods: Forty histologically proven esophageal carcinoma patients were treated in ARM A (3DCRT) and ARM B (IMRT) and were evaluated for clinical lung toxicity in each arm. Pulmonary function tests and chest radiographs were done preradiotherapy, 6 weeks of radiotherapy, and 6 months of radiotherapy for evaluation and thereafter compared for lung toxicity between both arms. RTOG lung toxicity grading was used to assess clinical lung toxicity. Results: We observed in the present study that lung toxicity was seen in patients of esophageal cancer postradiotherapy in both modalities. It was less in IMRT than 3DCRT but not of significant difference. Various levels of restriction were seen in pulmonary function test or spirometry that is mild, moderate, or severe. At 6 weeks of radiotherapy, in ARM A, five patients (25%) and in ARM B, and four patients (20%) had moderate restriction ( P value = 0.295). At 6 months of radiotherapy, in ARM A, seven patients (35%) and, in ARM B, five patients (25%) had severe restriction ( P value = 0.681). Conclusion: We observed that 3DCRT is comparable to IMRT in terms of lung toxicity in esophageal cancer patients as proven from clinical toxicity data. More follow-up is required to see the chronic changes and overall survival.