PIK3CA mutations in KRAS and BRAF wild type colorectal cancer patients. A study of Spanish population.

The objective of the work was to study PIK3CA mutations in wild type KRAS and BRAF colorectal cancer. Clinicopathological data and paraffin-embedded specimens were collected on 73 patients who underwent colorectal resections at General Yagüe Hospital in Burgos. KRAS, BRAF and PIK3CA status were analyzed by real-time PCR in all patients. PIK3CA mutations were present in 8.22% of wild type KRAS and BRAF colorectal cancers. The most frequent mutation is E545K/D in exon 9 which represents 83.3% of all mutations. By contrast, we did not found any tumour harbouring H1047R mutation in exon 20. Among the patients who undergo a curative resection of colorectal cancer, PIK3CA mutation is present in an important percentage of KRAS and BRAF wild type tumours. PIK3CA mutation may be considered as it could be a hypothetic reason to be not responder to anti-EGFR antibodies.