Is it permissible to omit mediastinal dissection for peripheral non-small-cell lung cancers with tumor diameters less than 1.5 cm?

Background: Recently the pros and cons of limited surgery for small-sized peripheral non-small-cell lung cancers (PNSCLCs), such as omission of mediastinal dissection, etc., have been vigorously debated. We analyzed whether hilar/mediastinal lymph node metastases were present in 30 small-sized PNSCLCs.
Material and Methods: In the nine years from 1990 to 1998, 294 lung cancer patients underwent lobectomy or pneumonectomy combined with hilar/mediastinal dissection in the Tokai University Hospital. Thirty of these patients diagnosed as having cT1N0M0 PNSCLC with tumor diameters of 1.5 cm or less by computed tomography, are evaluated in this article.
Results: The 30 PNSCLC patients consisted of 14 males and 16 females with a mean age of 61 +/- 9 years. Twenty six patients (87%) had no hilar nor mediastinal lymph node metastases (pN0), one patient (3%) had a hilar lymph node metastasis (pN1), and three patients (10%) had mediastinal lymph node metastases (pN2).
Conclusions: Mediastinal lymph node metastases were histologically observed in 3 (10%) of 30 PNSCLC patients with tumor diameters of 1.5 cm or less. Our results show that mediastinal dissection is still necessary even for small-sized lung cancers.