Protein abundance of class III beta-tubulin but not Delta2-alpha-tubulin or tau is related to paclitaxel response in carcinomas of unknown primary site.

Aim: To determine the prognostic value of microtubule component expression in tumors of patients with carcinomas of unknown primary site (CUP). Patients and Methods: Class III beta-tubulin, Delta 2-alpha-tubulin and tau protein were examined immunohistochemically in 51 CUP tumors from patients receiving paclitaxel and compared with their response to treatment. Results: The overall response rate was 18.4% among 49 evaluable patients. Delta 2-alpha-Tubulin and tau were not correlated with response or patient outcome. High class III beta-tubulin expression was correlated with both resistance to chemotherapy and shorter overall survival, while there was no relation with progression-free survival. In multivariate analysis taking into account clinical factors, class III P-tubulin expression was independently correlated with overall survival. Conclusion: These findings show that in tumor cells a high level of expression of class III beta-tubulin, but not Delta 2-alpha-tubulin or tau, is associated with resistance to paclitaxel and a poor prognosis in CUP patients receiving paclitaxel.