Extended RAS analysis and correlation with overall survival in advanced pancreatic cancer.

Background: Mutations in the KRAS gene can be detected in about 70-90% of pancreatic cancer (PC) cases. Whether these mutations have a prognostic or predictive value remains elusive. Furthermore, the clinical relevance of the extended RAS (KRAS+NRAS) mutational status is unclear in PC.

Methods: We prospectively defined a PC patient population who received erlotinib-free chemotherapy regimens. A statistically significant difference between KRAS wild-type and KRAS mutated tumours in at least 160 patients in this population would support the assumption of a rather prognostic role of KRAS.

Results: One hundred and seventy-eight tumour samples were collected from prospective clinical studies and successfully analysed for the extended RAS status: 37 tumours were KRAS wild-type (21%), whereas 141 (79%) carried a KRAS mutation; 132 of these mutations were found in KRAS exon 2 (74%), whereas only 9 mutations (5%) were detected in KRAS exon 3. Within KRAS exon 4 and NRAS exons 2-4, no mutations were apparent. There was no significant difference in overall survival for KRAS wild-type vs mutant patients (9.9 vs 8.3 months, P=0.70).

Conclusions: Together with the results of the AIO-PK-0104-trial, the present analysis supports the notion that KRAS mutation status is rather predictive than prognostic in advanced PC.