RESUMO
A prospective, non-randomized study was carried to assess the role of serial cytological assay in predicting radiosensitivity of squamous cell cancer of oral cavity in patients on fractionated radiotherapy (RT) and to evaluate the relationship of radiosensitivity with the histological grade of oral cancer. We studied 54 histologically proven cases of squamous cell carcinoma on cyclical radiotherapy treatment. Radiosensitivity was assessed using serial scrape smears taken before, during and after treatment with radiotherapy (4 & 8 weeks). Depending on the observed cytological change, patients were grouped in those showing good radiation response (sensitive) and those with poor radiation response (resistant) and their relation to cumulative dose of radiotherapy was analyzed for statistical significance. The changes such as multinucleation, micronucleation, karyorrhexis and cytoplasmic vacuolation occurring in irradiated cancer cells, had a statistically significant dose related increase with radiotherapy (P < 0.05). Less differentiated tumors were less radiosensitive and exhibited increased rate of persistence of dysplastic cells and a higher rate of recurrence (33%) after completion of radiotherapy as compared to well differentiated tumors. We recommend regular use of serial cytological assay as it provides valuable evidence of radiosensitivity and persistence of tumor/dysplastic cells at 8 weeks post-radiotherapy.