Comparison of imaging TNM [(i)TNM] and pathological TNM [pTNM] in staging of bronchogenic carcinoma.

OBJECTIVE

Precise tumor (T) and nodal (N) staging is imperative in non-small cell lung cancer (NSCLC) as it determines subsequent treatment, certainly when considering neoadjuvant treatment for stage IIIA or IIIB disease. To determine the accuracy of present-day computed tomographic (CT) scanning a prospective study was performed comparing imaging TNM [(i)TNM] and pathological TNM [pTNM].

METHODS

In 74 patients with NSCLC without distant metastases (i)TNM was determined on CT findings. The TNM system advocated by the American Joint Committee on Cancer was used. All patients underwent cervical mediastinoscopy. When superior mediastinal nodes were negative this was followed by thoracotomy and pathological examination of the resected specimen and lymph nodes to determine pTNM.

RESULTS

The agreement between (i)TNM and pTNM was only 35.1%. The primary tumor (T) was correctly staged in 54.1%, overstaged in 27.0% and understaged in 18.9% of the patients. Invasion of chest wall, pericardium and of major mediastinal structures (T3, T4) was not reliably detected by CT scan. Sensitivity and specificity of CT regarding hilar and mediastinal lymph node staging were 48.3 and 53.3%, positive and negative predictive value 40 and 61.1% and its overall accuracy 51.4%. The nodal (N) factor was correctly determined by CT scan in 35.1%, overstaged in 44.6%, and understaged in 20.3% of the patients.

CONCLUSIONS

Even with present-day CT scanners (i)TNM provides no accurate staging and routine mediastinoscopy is necessary for precise mediastinal lymph node staging. Likewise, (i)T3 and (i)T4 determinations are unreliable and should not contraindicate thoracotomy.