Increased expression levels of cyclin-dependent kinase inhibitor p27 correlate with good responses to platinum-based chemotherapy in non-small cell lung cancer

In order to determine whether expression of the cyclin-dependent kinase inh ibitor p27 in non-small cell lung cancer (NSCLC) correlates with chemothera peutic response, resected tumors from 22 patients with recurrent lung cance r who had undergone complete resection and received chemotherapy after the initial tumor recurrence were subjected to p27 immunostaining. Histological examination of the resected tumors revealed 14 adenocarcinomas, 7 squamous cell carcinomas and one adenosquamous cell carcinoma. Fifty percent or les s and over 50% of the cells in the resected tumors of 11 patients each (gro ups I and 2, respectively) were p27-immunopositive. All but one patient rec eived platinum-based chemotherapy after recurrence. Only one in group 1 ach ieved a partial response (PR) in chemotherapy whereas 2 and 4 in group 2 ac hieved complete and PRs, respectively. The chemotherapy response rate of gr oup 2 (54%) was significantly higher than that of group I (9%, p=0.022). Th e times to reccurrence after tumor resection of the 2 groups did not differ significantly (log-rank p=0.23, Wilcoxon p=0.32), but survival after chemo therapy of group 2 was significantly better than that of group 1 (log-rank p=0.045, Wilcoxon p=0.028). It is suggested that high p27 expression levels in tumors may predict the good responses to platinum-based chemotherapy fo r NSCLC.