RAS testing in metastatic colorectal cancer: excellent reproducibility amongst 17 Dutch pathology centers.

In 2013 the European Medicine Agency (EMA) restricted the indication for anti-EGFR targeted therapy to metastatic colorectal cancer (mCRC) with a wild-type RAS gene, increasing the need for reliable RAS mutation testing. We evaluated the completeness and reproducibility of RAS-testing in the Netherlands. From 17 laboratories, tumor DNA of the first 10 CRC cases tested in 2014 in routine clinical practice was re-tested by a reference laboratory using a custom next generation sequencing panel.

Allelic imbalance in the diagnosis of benign, atypical and malignant Spitz tumours.

To test the diagnostic usefulness of allelic imbalance (AI) analysis based on routinely paraffin-embedded tissue, a series of 55 benign Spitz naevi, Spitz tumours with uncertain malignant potential, and malignant Spitzoid melanomas was investigated. Laser microdissection was used to ensure representative sampling of lesional cells and to investigate AI in separate tumour areas of four melanomas. AI was found in 2/12 (17%) typical Spitz naevi, 3/9 (33%) atypical Spitz tumours, 12/17 (65%) atypical Spitz tumours suspicious for melanoma and 15/17 (88%) Spitzoid melanomas.