Tumor dimension-dependent microscopic extensions of hypopharyngeal cancer: Therapeutic implications for larynx-preserving hypopharyngectomy.

INTRODUCTION: Hypopharyngeal cancer (HPC) is well characterized by the early submucosal spread of cancer cells into adjacent subsites of the hypopharynx and deep tissues, advocating a wide extent of treatment. However, the microscopic extensions (ME) from gross tumors, according to the primary tumor dimensions, has not been reported in detail. METHODS: We included patients who underwent upfront curative surgery, and retrospectively reviewed pathology specimens from 45 HPC cases. The distance of the MEs, defined as tumor infiltration beyond the gross tumor border on the submucosal and deep sides, was measured. We analyzed potential correlations between MEs and various physical tumor factors. RESULTS: A rough linear correlation between the submucosal ME and the maximal diameter of tumors was found (p < .001, r(2) = 0.225). Deep MEs did not correlate with tumor physical factors. However, the MEs differed significantly by the T status (p = .033 and .015 in submucosal and deep sides). In T1-2 tumors, the submucosal MEs were less than 0.5 cm, whereas those of T3-4 tumors were 1.5-2.0 cm. CONCLUSION: In HPC, local MEs beyond the gross tumor border correlated with primary tumor T status. Our findings support that the surgical safety margin for HPC can be adjusted according to tumor dimension.