EGFR and KRAS molecular genotyping for pulmonary carcinomas: Feasibility of a simple and rapid technique implementable in any department of pathology.

OBJECTIVES

EGFR and KRAS genes are routinely tested in lung carcinomas with therapeutic implications. However the current testing methods require complex infrastructures and the delay for diagnosis remains often rather long, especially for initiating an appropriate treatment in patients with advanced stage tumor and short life expectancy.

MATERIAL AND METHODS

We evaluated the Idylla™ fully automated molecular diagnostic system in routine conditions in 79 lung adenocarcinomas and 14 other non-small cell lung carcinomas, mostly in advanced stages (III or IV: 85%). Tests were performed on formalin-fixed paraffin-embedded (n=83) or fresh (n=10) material, including cytological (n=24) and small biopsy (n=20) samples. In prospective cases (n=82), the most likely mutated gene (EGFR in non or occasional smokers and KRAS in smokers) was tested first; the second gene being only tested in case of negativity.

RESULTS

The system did not require complex training. Mutational status was obtained in few hours after making the histological diagnosis and on the day of the patient's sampling by analyzing fresh material. The sequential testing strategy avoided 15 EGFR and 15 KRAS tests that would have been negative. Compared with reference methods, global specificity and sensitivity were both 100% for EGFR mutations, and 89.1% and 91.7% for KRAS mutations, respectively.

CONCLUSIONS

We demonstrated that such easy-to-use systems can permit pathologists to integrate a reliable EGFR/KRAS status in their initial pathologic report, and could be useful complementary tools to the current molecular diagnostic methods, with regard to prompt therapeutic management of lung cancer patients.