786 - Clinical-dosimetric analysis of factors predisposing to chronic dysphagia measured using CTCAE criteria among locally advanced oropharyngeal cancer patients treated definitely by intensity modulated radiotherapy with concurrent chemotherapy

Background

Concurrent chemoradiotherapy in oropharyngeal cancers results in anatomical changes to the pharyngeal constrictors (PCM), larynx and parotid gland leading to chronic dysphagia. This study was done in to find out the incidence of chronic dysphagia after CRT and analyse its correlation with patient clinical factors and specific dose volume parameters of PCM, larynx, oral cavity and parotid glands in locally advanced oropharyngeal cancer patients undergoing concurrent chemoradiotherapy.

Methods

52 patients with KPS ≥70 of stage III-IVA oropharyngeal cancers were enrolled and treated with concurrent chemoradiotherapy between 2012-2014 with IMRT dose of 66Gy in 30 fractions and 5 cycles of weekly cisplatin 40mg/m². Patient clinical factors and Doses to the PCM, larynx, oral cavity and parotid glands such as Mean dose, V₅₀ and V₆₀ were measured from dose volume histograms. Clinical dysphagia was measured at baseline and after 6 months of completing CRT using CTCAE v4.03. These factors were analysed for their correlation with the severity of post CRT chronic dysphagia.

Results

It was found that the clinical factors such as pretreatment dysphagia, nodal stage, TNM stage, tumor volume and mucositis grade at CRT completion had a significant correlation with post CRT chronic dysphagia. On applying spearman's correlation coefficient for dosimetric factors it was found that the Mean dose, V₅₀ and V₆₀ of PCM, larynx and the mean dose of parotid gland and oral cavity had a positive significant correlation with the severity of post CRT chronic dysphagia. On ANOVA statistical analysis it was found that the Mean dose, V₅₀ and V₆₀ of pharyngeal constrictor, larynx were significant in predicting the post CRT chronic dysphagia. Predictive equations to Odds of post CRT chronic dysphagia were generated.

Conclusions

Post CRT chronic dysphagia is significant and based on this study results the following dosimetric parameters are recommended in predicting and reducing post CRT chronic dysphagia.Dose for PCM: Mean dose

Clinical trial identification

Legal entity responsible for the study

Karthik Periasamy

Funding

Bhagwan Mahavir Cancer Hospital and Research Center, Jaipur

Disclosure

All authors have declared no conflicts of interest.