A Comparative Study of the Acute Toxicities of Three-Dimensional Conformal Radiotherapy (3D-CRT) Versus Intensity-Modulated Radiotherapy (IMRT) in Locally Advanced and Inoperable Oral Cavity Cancer.

Background Oral cavity cancer is a substantial and increasing public health burden in Bangladesh due to widespread tobacco abuse and betel nut chewing. According to GLOBOCAN 2022, oral cavity cancer is the second most common cancer in Bangladesh after esophageal cancer. Locally advanced and medically inoperable oral cavity cancer can be treated with concurrent chemoradiotherapy (CCRT) as an established standard of care, which can be delivered using either three-dimensional conformal radiotherapy (3D-CRT) or intensity-modulated radiotherapy (IMRT) techniques. Methods This quasi-experimental study was carried out among 84 patients with locally advanced and inoperable oral cavity cancer (LAIOCC) from December 2022 to October 2023 who fulfilled the eligibility criteria and were equally distributed (42 in each arm) into two treatment arms. Arm A received CCRT with 3D-CRT and weekly cisplatin (40 mg/m²), whereas Arm B received IMRT with weekly cisplatin (40 mg/m²). Follow-up was conducted weekly during chemoradiotherapy and at the sixth week after completion of treatment. Results Xerostomia was observed more frequently in the 3D-CRT arm than in the IMRT arm (p = 0.04). Similarly, dysphagia occurred more often in the 3D-CRT arm than in the IMRT arm (p = 0.02). However, the difference in mucositis was not statistically significant (p = 0.22). Likewise, the difference in dermatitis between the two arms was not statistically significant (p = 0.63). Acute hematological toxicities, including anemia (p = 0.75), leukopenia (p = 1.00), and thrombocytopenia (p = 0.52), also did not differ significantly between the arms. Conclusion IMRT was associated with a lower incidence of dysphagia and xerostomia than 3D-CRT. Therefore, the IMRT technique provides a significant benefit to patients with oral cavity carcinoma compared with the 3D-CRT technique in terms of acute toxicities, particularly xerostomia and dysphagia.