Radiotherapy in the treatment of verrucous carcinoma of the oral cavity.

Verrucous carcinomas are considered to have poor radioresponsiveness and radiotherapy has been reported to induce anaplastic transformation. Surgery has been considered to be the primary mode of treatment for these tumours. The clinical features, response to radiotherapy, survival and prognostic factors of a group of 53 patients with oral verrucous cancers, were studied and compared to patients with oral well-differentiated, squamous cancers, treated during the same time period. The buccal mucosa was the commonest primary site in both groups. 42 patients with verrucous cancer underwent primary radiotherapy and 11 underwent primary surgery. Complete response to radiotherapy was achieved in 76% of patients with verrucous cancer and partial response in 24%. Patients with verrucous cancer had a five year actuarial disease-free survival of 66% and overall survival of 86%. The corresponding survival figures were 43% and 56% in well-differentiated squamous cancers (P = 0.004). Composite stage of disease was a significant predictor of disease-free survival in both groups. None of the 16 patients with verrucous cancers that recurred after radiotherapy, had features of anaplastic transformation. Oral verrucous carcinoma appears to have similar radioresponsiveness and improved disease-free survival, compared to well-differentiated squamous cancers. The treatment policies for other oral squamous cancers are applicable to these tumours.