THE NEW LUNG CANCER CLASSIFICATION MAY NEED FINE TUNING

NEW YORK (Reuters Health) Oct 09 - Some lung cancer patients classified as T3 by the new TNM classification, seventh edition should be redefined as T2b, say researchers from The University of Texas M. D. Anderson Cancer Center in Houston.

"Outcome prediction should be individualized for each patient," Dr. Edward S. Kim told Reuters Health. "Even within one stage, tumor and patients characteristics may help identify individuals who will have better outcome, and thus allow us to tailor treatment commensurate with each patient's prognosis."

In the September issue of Chest, Dr. Kim and his colleagues present a detailed analysis of data from the Surveillance, Epidemiology, and End Results (SEER) program on more than 22,000 patients with stage IIIB and IV non-small cell lung cancer.

Among patients with stage IIIB disease, factors associated with better survival outcome included age below the median, female gender, Asian race, bronchoalveolar histology, tumor size below the median, T1, T4 satellite and T4 invasive, N0, and surgery, radiotherapy, or both.

For patients with stage IV disease, age below the median, female gender, Asian race, adenocarcinoma and bronchoalveolar histology, tumor size below the median, N0, M1 ipsilateral and M1 contralateral, and surgery, radiotherapy, or both were associated with better survival.

When the researchers analyzed outcomes according to the sixth edition of the TNM classification, patients with T4 satellite lesions had survival curves more similar to patients in the T2 group than to patients in the modified T3 group, the investigators say, suggesting that patients with T4 satellites should be redefined as T2b.

"Should the seventh edition of the TNM classification for lung cancer be modified to downstage ipsilateral same-lobe pulmonary nodules?" asks Dr. Julian R. Molina from Mayo Clinic College of Medicine, Rochester, Minnesota in a related editorial. "The answer is 'no' at this time."

Dr. Molina cites the lower number of patients in these subgroups compared with the overall total as one reason to be cautious in suggesting revision.

"It is extremely important to continue to expand the existing populational databases, which will provide invaluable knowledge to refine outcome prediction," Dr. Kim said. "Hopefully, in the future, we will be able to integrate information on molecular biomarkers to these databases, with the ultimate goal of developing more accurate prognostic models."

"We are currently investigating other ways of refining predictions of survival outcome based on clinical characteristics," Dr. Kim added. "One such strategy currently on investigation is evaluating outcomes according to tumor size (analyzed as a continuous variable) across all combinations of T and N subgroups. Hopefully this will allow us to construct an accurate model to predict outcome based on multiple variables beyond those that are already contemplated in the TNM classification, including size, primary tumor characteristics, lymph node status, age, histology, etc."

Chest 2009;136:660-661,701-709.