Prognostic implication of Ki-67 immunostaining in treating subclinical pleural cancer found at thoracotomy in lung cancer patients

Background. Therapeutic principles for managing subclinical pleural cancer found unexpectedly during intraoperative examination are unclear. We analyz ed prognostic factors including the tumor proliferative marker Ki-67 in the se circumstances. Methods. The cases of 65 surgically treated patients with lung cancer and s ubclinical T4 pleural cancer, microscopic in 25 and macroscopic in 40, were reviewed. Results. The overall 5-year survival rate of patients undergoing lobectomy was 14.3%. For patients with T4 NO disease, the 5-year survival rate was 46 .7%. In patients with a low Ki-67 labeling index, the 5-year survival rate was 28.6%. The Ki-67 labeling index was a significant (p < 0.05) indicator of survival. Multivariate analysis demonstrated Ki-67 labeling index, lymph node involvement, and tumor differentiation to be the most influential pro gnostic factors for postoperative survival (p < 0.01). Conclusions. In the treatment of lung cancer patients with subclinical pleu ral cancer found at thoracotomy, tumor resection is not necessarily contrai ndicated. Resection appears to be beneficial in patients with no nodal invo lvement or a low tumor Ki-67 labeling index. This index is a good therapeut ic indicator for lung cancer patients.