Primary tumor, node location important in stage III NSCLC prognosis

Researchers from Japan say that classifying clinical mediastinal lymph node status based on the location of the primary tumor and the node involved could improve prognosis in stage III non-small-cell lung cancer (NSCLC) compared with pathologic node status.

Kenji Suzuki and colleagues, from the Juntendo University School of Medicine in Tokyo, analyzed data on 1257 patients who underwent resection for primary lung cancer between 1996 and 2009 and identified 78 patients with clinical (c)N2, c-stage IIIA, pathologic (p)N2 NSCLC.

The team defined two secondary classifications of cN2 status: cN2α where there is upper mediastinal lymph node (UMLN) involvement for an upper lobe primary tumor or lower mediastinal lymph node (LMLN) involvement for a lower lobe primary tumor; and cN2β where there is LMLN involvement for a main tumor in the upper lobe (with or without metastatic UMLN) or UMLN involvement for a main tumor in the lower lobe (with or without metastatic LMLN).

The median follow-up was 48.9 months and the overall 5-year survival rate was 30.6%. Overall, there were 60 (76.9%) cN2α patients and 18 (23.1%) cN2β patients, and 52 (66.7%) pN2α patients and 26 (33.3%) pN2β patients.

The researchers found that disease-free 5-year survival was significantly better when the tumor was located in the upper lobe compared with the lower lobe, at 27.9% versus 11.1%. There was also a significant difference in disease-free 5-year survival between patients with cN2α status and cN2β status, at 29.6% versus 0.0% and, in multivariate analysis, cN2α was an independent predictor for disease-free survival, at a hazard ratio of 0.424 versus cN2β status.

However, among the 45 patients with single cN2 disease there was no significant difference in 5-year survival compared with the 33 patients with multiple cN2 disease (23.4 and 19.5%, respectively).

Writing in the European Journal of Cardiothoracic Surgery, Suzuki et al explain that patients with cN2 stage IIIA NSCLC are a heterogenous group, for whom the ideal treatment strategy remains controversial.

“Our present study revealed the importance of the location of the primary tumour and the nodes involved in patients with clinical stage IIIA NSCLC,” they write.

The team also notes that 64.4% of single-station cN2 was multiple-station pN2, which is an important factor in the decision to surgically resect, and could affect the interpretation of previous study findings based on pathologic status only.

They conclude: “[C]linical mediastinal lymph node status based on the location of the primary tumour and the node involved was found to be an important preoperative prognostic factor. Thus, this factor should be taken into consideration when planning and evaluating clinical trials.”

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