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Vol.52 No.1 contents | Japanese/English |
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- The 25th Lung Cancer Workshop -
Problems of the New TNM Classification of Lung Cancer from the Standpoint of Radiotherapy
Yuko Nakayama1, Tetsuo Nonaka1, Nobutaka Mizoguchi11Department of Radiation Oncology, Kanagawa Cancer Center, Japan
Objective. To discuss the problems of the 7th revision of the TNM classification of lung cancer from the standpoint of radiotherapy. Methods. The following changes have been made in the 7th Edition of the TNM classification of lung cancer: 1) new subclassification by tumor size; 2) the reclassification of pleural dissemination as M1a; 3) and the reclassification of T4 tumors by additional nodule (s) in the lung (primary lobe) as T3. Regarding N factors, the entire subcarinal group of lymph nodes, previously labeled as level 7 on the Mountain Dresler modification of the American Thoracic Society (MD-ATS) map but divided into levels 7 and 10 in the Naruke map, is now defined as level 7. Problems related to these changes in the new revision of the TNM classification are discussed from the standpoint of radiotherapy. Results. There is a possible correlation between tumor size and radiation effect. In the 7th Edition, T1 is subclassified as either T1a (≤2 cm) or T1b (≥2 cm-3 cm). Further analysis of patients with small lung lesions is needed to clarify the impact of reclassifying T1 tumors on the clinical outcomes of stereotactic radiotherapy (SRT). The new subclassification of T2 as T2a (3 cm-5 cm, or T2 by other factors and 5 cm or more) or T2b (5 cm-7 cm) is useful. Cases of pleural dissemination are not indicated for definitive radiotherapy, and thus, the reclassification of M1a is reasonable. Tumors with an additional nodule in the primary lobe, previously defined as T4, are now classified as T3. The subcarinal group of lymph nodes, including levels 7 and 10 in the previous (MD-ATS) map, was defined as level 7 in the current staging system. These new definitions do not indicate definitive radiotherapy for patients with T3 or N2. Conclusion. Compared with the 6th Edition of the TNM classification of lung cancer, a number of changes in the 7th Edition are considered to be compatible with indications for radiotherapy. On the other hand, careful evaluation of the tumor is necessary, because some patients with T3 or N2 may not be candidates for curative radiotherapy.
key words: Lung cancer, UICC-TNM (7), Radiotherapy
JJLC 52 (1): 101-104, 2012
