TNM Staging of Limited-Stage Small-Cell Lung Cancer

Assessment by Bronchomediastinoscopy and Chest Radiography

Abstract

Small-cell lung cancer (SCLC) is generally classified as either limited or extensive disease. Recently it has been recommended to use the TNM classification (UICC 1987) when treatment involves local modalities. In the present study, we investigated whether it is possible to stage SCLC according to this TNM classification by the use of chest radiography, bronchoscopy, and mediastinoscopy. Twenty patients defined as having limited-stage SCLC were randomly selected of a series of 199 patients treated in a randomized prospective trial. In 30% of the patients the tumor size and presence of regional hilus and mediastinal lymph nodes could not be assessed by the use of chest radiographs. Also, it was not possible to evaluate tumor invasion into neighboring structures in any of these patients, and a T-stage classification was possible only if these evaluation problems were not taken into account. The T-stage is therefore likely underestimated in some of the patients classified as T1/T2. By the use of radiologic examination, 15% were classified as NO. 30% as N1, 25% as N2 + N3, and 30% as NX. By the use of mediastinoscopy, 70% were classified as NO, and 30% as N-positive. Agreement between staging of lymph nodes by radiography and staging by mediastinoscopy was obtained in only 40% of the patients. Staging of patients with SCLC strictly according to the TNM classification is not possible based on chest radiography and bronchomediastinoscopy. Using computed tomography and magnetic resonance imaging scanning will not solve the staging problems, as they also have limitations in assessing tumor invasion as well as hilar and mediastinal lymph node involvement. Therefore, further advances in staging techniques are needed.