The seventh edition of the International Association for the Study of Lung Cancer’s tumor, node, metastasis (TNM) classification appears to be a better predictor of local or regional recurrence of lung cancer following surgery, according to the findings of a recent study.

Researchers at Duke University School of Medicine (Durham, North Carolina) reviewed the cases of 709 patients undergoing surgery for non-small cell lung cancer (NSCLC) between 1995 and 2005. None of the patients had received chemotherapy or radiation therapy, and none had sublobar resections with positive margins or involvement of the chest wall.

During a median follow-up of 32 months, the 5-year actuarial risk of local/regional recurrence (disease recurrence at the surgical margin or within ipsilateral hilar and/or mediastinal lymph nodes) was 23%. When patients were converted from TNM 6 classification to TNM 7, approximately 13% were placed in a higher stage and approximately 8% in a lower stage.

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Five-year recurrence rates for stages IA, IB, IIA, IIB, and IIIA disease using TNM 6 were 16%, 26%, 43%, 35%, and 40%, respectively. Corresponding rates using TNM 7 (published in 2009) were 16%, 23%, 37%, 39%, and 30%, respectively.

“The TNM 7 system seems to be a better predictor for [local/regional recurrence] after surgery for NSCLC than TNM 6,” wrote the investigators in Journal of Thoracic Oncology (2011;6[4]:757-761). “This information may prove to be valuable when designing future studies of postoperative [radiation therapy].