Improvement in management of advanced cervical cancer after radiotherapy requires a better understanding of its biological behavior. PTEN/MMAC/TEP (PTEN), a candidate tumor suppressor gene located at chromosome 10q23. 3, was recently identified and found to be frequently mutated in several different types of human tumors. In contrast, rare mutations of the PTEN gene have been reported in cervical cancer. The aim of this study was to determine whether mutation of PTEN leads to increased genomic alteration in advanced cervical carcinoma, and to identify the correlation between mutation of PTEN and patient outcome after radiotherapy. We examined 50 primary advanced cervical carcinomas (37 patients of Stage IIIB, 13 patients of Stage IVA) treated with definitive radiotherapy using a PCR-based assay followed by SSCP and direct sequencing. The PTEN gene was mutated in 8 of the 50 (16%) patients (2 of Stage III, and 6 of Stage IV). There was a significant difference in Stage III versus IV between the wild-type PTEN patients and mutant PTEN patients (P= 0.002). The tumor size was 6±2.1 cm in the wild-type PTEN tumors versus 8.5±2 cm in the mutant PTEN tumors (P= 0.009). In addition, there was a significant difference in survival between the wild-type PTEN patients and mutant PTEN patients (P= 0.009). The results of this study suggest that the PTEN gene mutation rate increases with tumor progression, and that the PTEN gene may play a role in both progression of cervical carcinoma and treatment outcome.