口腔領域へん平上皮癌の所属リンパ節転移に関する臨床的，病理組織学的研究

Abstract

Fifty-two patients with squamous cell carcinomas of the oral cavity, oropharynx, and maxillary sinus who underwent neck dissection were clinico-pathologically reviewed. Maxillary sinus and tongue carcinomas showed high incidences of lymph node metastases. In contrast, carcinomas of the lower gum and oropharynx had low incidences of lymph node metastases. Of the 36 cases with histologically positive nodes, level 2 was the most frequent site of metastases followed by level 3, level 1, and level 4 at the affected side. Metastasis contralateral to level 2 was not infrequently observed. Non-contiguous nodal sites were observed in 2 patients with bilateral metastases. The largest number of metastatic nodes was 18, but the largest proportion of cases in this series had only one positive node. There was some correlation between the number of involved nodes and the level of metastasis. In relation to T category, many of the T 1 cases had only one affected node, but the numbers of involved nodes varied considerably in T2, T3 and T4 cases. The cumulative 5-year survival rate was 86.7% in pN (+) cases, versus 62.4% in pN (-) cases, and this difference was significant (P<0.05). Patients with more than 6 involved nodes showed a poor 5-year survival rate (14.7%). There was no statistical significance in 5-year survival between immediate dissection and subsequent therapeutic dissection.The metastatic nodes were classified into 3 types according to the localization of tumor nests: marginal type, paracortical type, and replaced type. The replaced type accounted for 60% of all affected nodes, the paracortical type for 30%, and the marginal type for 10%. In the marginal type and the paracortical type, the majority of nodes were 9 mm or less in maximum diameter. In contrast, the replaced type nodes were 10mm or more in maximum diameter. Capsular invasion and extranodal spread were observed primarily in the replaced type. Extranodal spread was not found in the marginal type. The 5-year survival rate for patients with capsular invasion or extranodal spread without fibrous thickening of the nodal capsule was much poorer than those with fibrous thickening. The results suggest that fibrous thickening of the nodal capsule may inhibit the extension of extranodal spread. Independent of the tumor nest localization within the node, juxtacapsular tumor emboli of the metastatic nodes were observed in 17.1% of all metastatic nodes, and the 5 year survival rate for these cases was low.