K H Lam1, L K Lam, C M Ho, W I Wei. 1. Department of Surgery, Queen Mary Hospital, the University of Hong Kong, Hong Kong.
Abstract
PURPOSE: Efforts to conserve the mandible in resection for oral cancer tend to bring the resection margin progressively closer to the tumor front. This study of the manner of mandibular invasion by carcinoma of the lower alveolus provides added information regarding the behavior of the cancer within the bone. MATERIALS AND METHODS: Twenty-four resected specimens of squamous carcinoma of the lower alveolus were studied with x-rays and step-serial whole-organ histological sections. RESULTS: In 19 of the 21 specimens showing bone invasion, the spread was in the form of a broad front. Insinuation of tumor beyond the tumor front was extensive in 9 of 13 tumors showing deep mandibular invasion. Horizontal subcortical spread took place in 5 of 18 specimens for a distance of up to 1 cm. Perineural spread along the inferior alveolar nerve was found in 4 of 13 specimens in which the tumor extended to the canal; tumor spread along the canal, without neural involvement, was never seen. Preoperative orthopantomogram correctly estimated the extent of mandibular invasion in 16 of 24 patients. CONCLUSIONS: The tumor front of mandibular invasion by carcinoma of the lower alveolus is usually broad. In the absence of deep invasion, which is defined by invasion reaching the alveolar canal, there is little or no insinuation of cancer cells beyond the tumor front, and no spread along the alveolar canal. Marginal mandibulectomy can be applied more widely, taking a margin of 1 cm in all directions.
PURPOSE: Efforts to conserve the mandible in resection for oral cancer tend to bring the resection margin progressively closer to the tumor front. This study of the manner of mandibular invasion by carcinoma of the lower alveolus provides added information regarding the behavior of the cancer within the bone. MATERIALS AND METHODS: Twenty-four resected specimens of squamous carcinoma of the lower alveolus were studied with x-rays and step-serial whole-organ histological sections. RESULTS: In 19 of the 21 specimens showing bone invasion, the spread was in the form of a broad front. Insinuation of tumor beyond the tumor front was extensive in 9 of 13 tumors showing deep mandibular invasion. Horizontal subcortical spread took place in 5 of 18 specimens for a distance of up to 1 cm. Perineural spread along the inferior alveolar nerve was found in 4 of 13 specimens in which the tumor extended to the canal; tumor spread along the canal, without neural involvement, was never seen. Preoperative orthopantomogram correctly estimated the extent of mandibular invasion in 16 of 24 patients. CONCLUSIONS: The tumor front of mandibular invasion by carcinoma of the lower alveolus is usually broad. In the absence of deep invasion, which is defined by invasion reaching the alveolar canal, there is little or no insinuation of cancer cells beyond the tumor front, and no spread along the alveolar canal. Marginal mandibulectomy can be applied more widely, taking a margin of 1 cm in all directions.