Analysis of time-dose factors in squamous cell carcinoma of the oral tongue and floor of mouth treated with radiation therapy alone

This is a retrospective analysis of 147 patients with squamous cell carcinoma of the oral tongue and floor of mouth who were treated with radical radiation therapy at the University of Florida between October 1964 and December 1977. Control of the primary lesion was analyzed in respect to total dose, time, treatment modality, and split vs. continuous course therapy. There is an increase in local control of T2 lesions of the oral tongue with treatment by radium alone or radium and less than 3000 rad external beam irradiation as compared to radium and 3000 rad or more external beam (p = 0.02) and in T3 lesions of the floor of mouth with treatment by radium and 3000 rad or more external beam as compared to external beam alone (p = 0.11). Analysis of time-dose factors reveals an increase in local control with increasing dose over shorter periods of time in T3 lesions of the floor of mouth and T2–3 lesions of the oral tongue. Whereas dose appears to be important in all of these groups, overall treatment time appears to influence local control more in oral tongue lesions than in floor of mouth lesions.