Clinicopathological factors associated with unexpected N3 in patients with mediastinal lymph node involvement.

INTRODUCTION

We have already shown that postoperative survival was poor in p-N3 patients from the experience of extended radical nodal dissection (ERD: cervical and bilateral mediastinal nodal dissection) for lung cancer. In this retrospective study, we aimed to clarify the clinicopathological factors associated with p-N3 in patients with mediastinal lymph node involvement (excluding c-N3) who underwent ERD, and we studied their impact on prognosis.

METHODS

Between 1996 and April 2006, in patients with lung cancer in the right upper lobe, we performed ERD after obtaining informed consent from the patients. The study comprised 8 females and 29 males (median age of 60 years), with 15/7/15 cases of c-N0/c-N1/c-N2, respectively. The clinicopathological records of each patient were examined for prognostic factors associated with p-N3, including age, gender, histology, c-N number, preoperative serum CEA level, number of metastatic stations, and distribution of metastatic nodes according to the system of Naruke et al. Because c-N3 cases were excluded from the study, we defined p-N3 as unexpected N3.

RESULTS

Of the 37 study subjects, 19 (51.4%) had one or more metastases to the mediastinal lymph nodes. Of these 19 patients, 10 (52.6%) had metastases to cervical and/or contralateral mediastinal lymph nodes (unexpected N3; 5-year survival was 0%). C-N factor (c-N2), nonskip N2, multistation mediastinal lymph node metastasis, highest mediastinal nodal involvement, and pT status were significantly associated with unexpected N3. In particular, multistation mediastinal lymph node metastasis and highest mediastinal nodal involvement were significant prognostic factors in multivariate analyses.

CONCLUSIONS

Because unexpected N3 patients showed a poor prognosis after ERD, treatment modalities other than surgery should be considered. On the other hand, because true N2 patients showed a good outcome after surgery, surgical resection may be considered an important therapeutic modality even for N2 patients, given that they show single-station mediastinal nodal involvement or c-N0-1.