Clinicopathologic features of peripheral squamous cell carcinoma of the lung

Background The clinicopathologic features are still unknown in peripheral squamous cell carcinoma of the lung, unlike centrally located carcinomas. In this retrospective study, we investigated the clinicopathologic characteristics of patients with peripheral squamous cell carcinomas. Methods Of 1,381 primary lung carcinomas surgically resected at the National Cancer Center Hospital, Tokyo, from 1995 through 2001, 70 (5.1%) peripheral squamous cell carcinomas of 3.0 cm or less in diameter were studied retrospectively in terms of clinicopathologic characteristics such as age, sex, past history, smoking, tumor size, mode of operation, extent of lymph node dissection, pathologic lymph node status, mode of recurrence, and cause of death. Results These patients ranged in age from 49 to 82 years, with a mean age of 69.2 years. Thirty-nine patients (56%) were at increased risk preoperatively. The incidence of lymph node metastasis was 25%, and larger tumors tended to be associated with a higher prevalence, although this difference was not significant (p = 0.12). None of the patients with N2 disease had skipping metastasis. Recurrence was observed in 13 patients (19%). There was no significant correlation between recurrence and the extent of lymphadenectomy or the mode of operation. The 5-year overall and disease-specific survival rates were 73.4% and 85.9%, respectively. The cause of death was recurrence in 53% and other disease in 47%. Conclusions We propose that mediastinal hilar lymphadenectomy should be routinely conducted as a curative operation for low-risk patients with small peripheral squamous cell carcinoma. We further propose that for patients who may have difficulty tolerating this procedure, pathologic examination of intraoperative frozen sections from the hilar node could be useful for planning a surgical strategy.