Resection margin as a predictor of recurrence at the primary site for T1 and T2 oral cancers. Evaluation of histopathologic variables.

Objective: To establish whether histopathologic variables other than the pathologist's statement of complete excision predict recurrence of squamous cell carcinoma at the primary site and therefore indicate local postoperative radiotherapy.

Design: Retrospective analysis of clinical data and review of slides of resection specimens.

Setting: Tertiary care, hospital-based clinic.

Patients: Eighty-two patients who had complete excision only (histologically based) of a T1 or T2 squamous cell carcinoma of the mobile tongue or floor of the mouth but did not receive any form of immediate postoperative radiotherapy. Twenty-nine patients underwent local resection without treatment of the NO neck; in 53 patients a neck dissection was also performed.

Methods: Evaluation of recurrent tumor above the clavicles until 4 years postoperatively and of second and third primaries. Infiltrative depth was evaluated in 73 cases and spidery spread, perineural spread, and angioinvasion in 70 cases.

Results: Of the squamous cell carcinoma, 27% were well differentiated and 73% were moderately differentiated; depth of invasion was 5 mm or more in 57%, a spidery growth pattern was present in 51%, there was perineural spread in 16%, and angioinvasion was found in 3%. Recurrences at the primary site, not linked to histopathologic findings, occurred in 4%; 17% of the patients had second primary tumors in the head and neck region, 15% had neck conversions, and 1% had neck recurrence.

Conclusions: When excision of a small squamous cell carcinoma of the mobile tongue or the floor of the mouth is histologically complete, other histopathologic variables are irrelevant in predicting recurrence at the primary site, and local radiotherapy is not indicated, considering the morbidity and high number of second and third primary tumors to be expected that will require future new treatment.