Objective:Oral squamous-cell carcinoma(OSCC)accounts for >90% of oral cancers affecting adults mostly between the fourth to seventh decades of life.The most common OSCC treatment is concomitant chemoradiotherapy(CCRT)having both locoregional and distant control,but CCRT has acute and chronic toxic effects on adjacent normal tissue.This study aimed to determine the side effects of CCRT on the oral mucosa and to characterize the clinicopathology of oral lesions in patients with OSCC.Methods:This descriptive,cross-sectional study was certified by the Ethical Review Committee(UHS/Education/126-12/2728)of the University of Health Sciences,Lahore,Pakistan.OSSC patients(n=81)with various histological subtypes,grades,and stages were recruited,and findings on their oral examination were recorded.These patients received 70,90,and 119 Gy of radiotherapy dosages in combination with the chemotherapy drugs cisplatin and 5-fluorouracil.Data were analyzed using SPSS 20.0.Results:The most common presentation of OSCC was a nonhealing ulcer(63%) involving tongue(55.6%).Clinical findings included mucositis(92.6%)and xerostomia of mild,moderate,and severe degrees in 11.1%,46.9%,and 35.8% cases,respectively.Ulcers(87.7%),palpable lymph nodes(64.2%),limited mouth opening(64.2%)and fistula(40.7%) were also observed.In females,the association of radiotherapy dosage with limited mouth opening,xerostomia,and histological grading was statistically significant(P<0.05).The association of chemotherapy drugs with xerostomia(P=0.003)was also statistically significant.Conclusions:CCRT induced mucositis,xerostomia,and trismus in patients with OSCC. Objective: Oral squamous-cell carcinoma (OSCC) accounts for> 90% of oral cancers affecting adults mostly between the fourth to seventh decades of life. The most common OSCC treatment is concomitant chemoradiotherapy (CCRT) with both locoregional and distant control, but CCRT has acute and chronic toxic effects on adjacent normal tissue. This study aimed to determine the side effects of CCRT on the oral mucosa and to characterize the clinicopathology of oral lesions in patients with OSCC. Methods: This descriptive, cross-sectional study was certified by the Ethical Review Committee (UHS / Education / 126-12 / 2728) of the University of Health Sciences, Lahore, Pakistan. OSC patients (n = 81) with various histological subtypes, grades, and stages were recruited, and findings on their oral examination were recorded. These patients received 70,90, and 119 Gy of radiotherapy dosages in combination with the chemotherapy drugs cisplatin and 5-fluorouracil. Data were analyzed using SPSS 20.0. Results: The most common presen The clinical findings included mucositis (92.6%) and xerostomia of mild, moderate, and severe degrees in 11.1%, 46.9%, and 35.8% cases, respectively. Ulcers (87.7%), palpable lymph nodes (64.2%), limited mouth opening (64.2%) and fistula (40.7%) were also observed. Females, the association of radiotherapy dosage with limited mouth opening, xerostomia, and histological grading was Significant (P <0.05). The association of chemotherapy drugs with xerostomia (P = 0.003) was also significantly significant. Conclusions: CCRT induced mucositis, xerostomia, and trismus in patients with OSCC.