In the management of solid tumors, testing of treatment-related biomarkers must produce accurate and reliable results, endorsing the need for external quality assessment (EQA) schemes. The Italian Association of Medical Oncology and the Italian Society of Pathology and Cytology created a permanent joint board to set up quality control (QC) schemes for the molecular characterization of tumors for therapeutic purposes. This board organizes EQA programs for the analysis of biomarkers in colorectal carcinoma (CRC), non-small cell lung carcinoma (NSCLC) and melanoma. Since the first EQA set-up in 2010, the number of participating laboratories has increased from 59 to 92 registered in 2015. Among all the programs, the percentage of successful centers ranges from 80.2 to 96.6% (Tab.1). Until the start of 2014, each EQA consisted of two rounds, while the successive programs were organized in one round. In 2011, 29.8% of centers failed the first round of the EGFR scheme; a similar result was obtained in 2013 (29.1%), whereas in 2015 only 13% of participants failed, despite it consisted of a single round (Tab.1). In the CRC programs organized in 2010 and 2012, results obtained in the first round were encouraging (96.6% and 88% respectively), while in 2014 a performance reduction was observed, with only 63.6% of participants passing the first round (Tab.1). This scheme was the first to require the analysis of full RAS and BRAF genes. Also, during the EGFR program in 2011 and the all-RAS/BRAF scheme in 2014, different efficiencies were noticed between the technologies, since commercial kits performed better than laboratory-developed methods. The collected data suggest that in general the molecular analyses are performed with good quality in Italy and that the constant participation in EQA programs allows to maintain these quality levels. However, the presence of two rounds could help the centers improve their outcome. The addition of new biomarkers to the routine diagnostics, as seen in the all-RAS/BRAF scheme in 2014, and the use of new techniques challenge the laboratories. Together, these data strongly underline the need for continuous education and trainings to ensure reliable molecular testing over time.Table: S04EQA scheme1° round (passed %)Final results (passed %)CRCKRAS EQA 201096,696,6KRAS EQA 201288,095,2RAS/BRAF EQA 201463,689,8NSCLCEGFR EQA 201170,287,2EGFR EQA 201370,980,2EGFR EQA 2015*one round87,087,0MelanomaBRAF EQA 201279,389,0BRAF EQA 2014*one round81,581,5* one round Open table in a new tab