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Very important histopathological factors in patients with resected non-small cell lung cancer: necrosis and perineural invasion.

BACKGROUND
The current staging system provides an anatomical classification of lung tumors; its secondary purpose is to allow the prognostic stratification of patients into homogeneous groups after surgery. In this work, intratumoral perineural invasion, lymphatic and blood vessel invasion together with the necrosis content of the tumor exclusive of the non-small cell cancer staging system were studied.


METHODS
During a 4-year period, 152 patients operated for non-small cell lung cancer (NSCLC) at our hospital were analyzed. Mean age of patients was 55.7 +/- 10.1 years.


RESULTS
Overall 5-year survival was 42.2 %. Mediastinal lymph node involvement, tumor size, incomplete resection, pneumonectomy, presence of necrosis and perineural invasion were significant prognosticators ( P = 0.03, 0.04, 0.0001, 0.046, 0.0246, < 0.0001, respectively). Multivariate analysis revealed that N status, perineural invasion, and the presence of necrosis were independent prognostic factors ( P = 0.006, P = 0.001, P = 0.001, respectively). Patients who had stage I tumor with necrosis and perineural invasion had a lower survival rate than those with stage IIIA tumor without these histopathological features ( P = 0.04). The presence of these histopathological characteristics in stage IIIA patients was a sign of a poorer prognosis ( P = 0.0001).


CONCLUSIONS
Perineural invasion and the presence of necrosis independently indicated a dismal prognosis and their prognostic power is comparable to those of the TNM classification. These factors could be candidates for better survival stratification and the indicators of the need for adjuvant therapy in early stage lung cancer patients.