Table 4. Overview of the distributed samples for each subscheme in the ESP lung EQA schemes between 2012-2015.

Subscheme	Scheme year	Nr of participants	Nr of samples distributed	Sample origin	Number of slides distributed per sample	Section thickness (μm)	Samples included in performance score	Educational samples (not included in performance score)
EGFR analysis	2013	107	4	4 cell lines	1	5	1 WT, 3 mut	0 WT, 0 mut
	2014	144	9	5 cell lines, 4 resections	2	5	2 WT, 7 mut	0 WT, 0 mut
	2015	114	10	10 resections	2	5	5 WT, 4 mut	0 WT, 1 mut
ALK IHC	2012	29	8	4 cell lines, 4 resections	2	5	4 +ve, 4 -ve	0 +ve, 0 -ve
	2013	48	12	6 cell lines, 6 resections	1	5	3 +ve, 9 -ve	0 +ve, 0 -ve
	2014	96	10	4 cell lines, 6 resections	2	3	2 +ve, 7 -ve	1 +ve, 0 -ve
	2015	95	5	5 resections	2	3	2 +ve, 3 -ve	0 +ve, 0 -ve
ALK FISH	2012	54	8	4 cell lines, 4 resections	2	5	3 +ve, 2 -ve	1 +ve, 2 -ve
	2013	100	12	6 cell lines, 4 resections	1	5	2 +ve, 3 -ve	2 +ve, 5 -ve
	2014	116	10	4 cell lines, 6 resections	1	5	2 +ve, 6 -ve	1 +ve, 1 -ve
	2015	111	5	5 resections	1	5	2 +ve, 3 -ve	0 +ve, 0 -ve
ALK FISH digital	2012	65	4	Digital images from resection specimens	NA	NA	2 +ve, 2 -ve	0 +ve, 0 -ve
	2013	106	4				2 +ve, 2 -ve	0 +ve, 0 -ve
	2014	81	4				2 +ve, 2 -ve	0 +ve, 0 -ve
	2015	111	5				2 +ve, 3 -ve	0 +ve, 0 -ve
ROS1 IHC	2014	31	10	4 cell lines, 6 resections	2	3	2 +ve, 8 -ve	0 +ve, 0 -ve
	2015	31	6	5 resections	2	3	2 +ve, 3 -ve	1 +ve, 0 -ve
ROS1 FISH	2014	56	10	4 cell lines, 6 resections	2	5	1 +ve, 7 -ve	1 +ve, 1 -ve
	2015	68	6	1 cell line, 5 resections	1	5	2 +ve, 3 -ve	1 +ve, 0 -ve
ROS1 FISH digital	2015	68	5	Digital images from resection specimens	NA	NA	1 +ve, 3 -ve	1 +ve, 0 -ve

The schemes of 2012 and 2013 are two pilot EQA schemes for which the set-up has previously been reported [17]. The following variants were part of the EGFR variant analysis schemes: c.2155G>A p.(Gly719Ser), c.2156G>C p.(Gly719Ala), c.2235_2249del p.(Glu746_Ala750del), c.2327G>A p.(Arg776His), c.2369C>T p.(Thr790Met), c.2573T>G p.(Leu858Arg), c.2300_2308dup p.(Ala767_Val769dup). Abbreviations: ALK, anaplastic lymphoma kinase; EGFR, epidermal growth factor receptor; EQA, external quality assessment; FISH, fluorescence in situ hybridization; IHC, immunohistochemistry; mut, mutated; NA, not applicable; Nr, Number; ROS1, proto-oncogene 1 tyrosine-protein kinase; WT, wild-type; +ve, positive; -ve, negative.