Survey population

Completed surveys were received from 275 laboratories in 45 different countries. The highest number of returned surveys were from France, Italy, the United Kingdom, Spain, and Canada (Fig. 1). Survey responses were collated and analysed descriptively.

Fig. 1

Number of laboratories per country from respondents who provided their location (n = 272)*. Values represent the number of participating laboratories per country. *A total of 3 laboratories out of the total 275 laboratories did not provide a response regarding the country they are located

A total of 161 out of the 275 laboratories surveyed reported their type of company. The majority of respondees (n = 85) were clinical testing laboratories, followed by diagnostic manufacturers (n = 20) and pharmaceutical companies (n = 2). A total of 54 laboratories reported “other”, which included academic centres/universities, public hospitals, and research foundations.

Molecular pathology testing

Out of 275 laboratories that shared data on this topic, 245 (89%) perform molecular pathology testing, whilst 29 (11%) do not — one laboratory did not provide information on this.

Molecular pathology testing targets

A summary of responses on testing targets received by the participating laboratories is displayed in Supplementary Figure 1a. Responses were received from 273 laboratories, of which 149 laboratories detailed the targets tested. The survey data showed that in laboratories only testing one target, the most common approach was mutation hotspot testing (22 laboratories). In laboratories testing multiple targets, the most common combination of testing was single gene, multiple gene, full coding regions, and targeted mutation regions (22 laboratories).

Overall, targeted mutation hotspots were the most common targets for laboratories (n = 102), with the least common being full coding regions of genes (n = 37) (Supplementary Figure 1b) and 84 and 89 laboratories, respectively, tested single- and multiple-gene targets.

ctDNA testing

There were 114 (41%) laboratories that reported the number of ctDNA diagnostic tests carried out in 2020 and their turn-around times. The majority of laboratories reportedly carried out <50 (n = 47, 41%) or 51–200 (n = 48, 42%) tests, with 12 reporting 201–500 tests, three reporting 501–1000, and four reporting >1000 tests. Three (3%) laboratories reported a turn-around time of either <1 day (<24 h) and four (4%) reported 2 days, with the majority reporting a time of either 7 days (n = 22, 22%) or 8–10 days (n = 24, 24%).

A total of 177 (64%) laboratories reported they offer a clinical diagnostic service using ctDNA testing, whilst 65 (24%) do not; 33 laboratories did not respond. Of those laboratories providing a diagnostic service (n = 177), most laboratories test in-house (n = 123), whilst 27 laboratories outsource their current clinical services, and 125 did not answer this question.

Current and planned testing

Responses regarding current ctDNA testing were received by 214 laboratories, with 198 responding to future testing plans. At the time of the survey, 130 laboratories reportedly performed research using ctDNA testing, with 84 stating they did not and 61 laboratories did not respond. A total of 21 laboratories that perform research using ctDNA testing reported no plans to implement further testing in the future. Of the laboratories that did not currently perform ctDNA testing (n = 84), 60 indicated that they plan to implement ctDNA testing in the future.

ctDNA testing methodologies

A total of 207 laboratories reported the testing methods used for ctDNA testing (Supplementary Figure 2). Data were not available for 56 laboratories. The most common testing method used by individual laboratories was NGS alone (n = 33), with 17 labs using amplicon-based NGS, 13 capture-based NGS, and three using both approaches. Real-time polymerase chain reaction (RT-PCR) was used independently of other methods by 25 laboratories. Of the 209 laboratories that reported testing methods, 74 reported using multiple methods, whilst 68 reported only using a single testing method.

Overall, RT-PCR was reported by 70 laboratories of which one laboratory each specified cobas® and allele-specific PCR (Supplementary Figure 2b). This was followed by ddPCR (n = 64), BEAMing (n = 6), MassARRAY by three, and End-point PCR by one laboratory. NGS was reported by 112 laboratories; 71 laboratories reported the use of amplicon-based NGS, and 41 reported capture-based NGS (Supplementary Figure 2b).

ctDNA target genesEGFR gene targets

Figure 2 illustrates EGFR (NM_005228.5) gene variants tested within the clinical diagnostic service of laboratories. A total of 130 laboratories tested the EGFR gene, whereas 72 did not include EGFR within the scope of their testing. The most common combination of gene testing targets was deletions in exon 19; insertions in exon 20, p.(Thr790Met), p.(Leu858Arg), and p.(Cys797Ser); and variants in codon 719, of which 92 laboratories applied this testing combination. The testing combination of deletions within exon 19; insertions in exon 20, p.(Thr790Met), and p.(Leu858Arg); and variants in codon 719 was applied by 13 laboratories. Only deletions within exon 19 were targeted by one laboratory and only p.(Thr790Met) was targeted by three laboratories; no other EGFR gene targets were reported to be targeted individually.

Fig. 2

A breakdown of the EGFR gene targets tested within the diagnostic clinical service of laboratories*. *The number of laboratories who did not provide EGFR targets are not included in this figure (n = 72), in addition to those laboratories who do not perform circulating tumour DNA testing (n = 65). EGFR nomenclature according to NM_005228.5

KRAS and NRAS gene testing

KRAS and NRAS variants tested by laboratories for both are presented in Fig. 3. A total of 272 laboratories reported whether they carry out gene testing; 97 laboratories reported testing for specific variants for KRAS, and 84 for NRAS.

Fig. 3

KRAS and NRAS gene targets tested within the diagnostic clinical service of laboratories. Nomenclature according to NM_004985.5 (KRAS) and NM_002524.3 (NRAS)

The most common targets for NRAS (NM_002524.3) were codons 12, 13, 59, 61, 117, and 146 (72 laboratories), whereas the most commonly tested regions for KRAS (NM_004985.5) were codons 12, 13, 59, 61, 117, 146, and p.(Gly12Cys) specifically (43 laboratories). Codons 12, 13, 59, and 61 were identified as testing targets in both KRAS (n = 8) and NRAS (n = 9) genes.

Other gene targets

A total of 24 other targets were reportedly included in testing strategies amongst the surveyed laboratories. These gene targets are displayed in Supplementary Table 1. The most commonly tested target was PIK3CA (NM_006218.3), with testing regions codon 542 (n = 88), codon 545 (n = 94), and codon 1047 (n = 93). Testing of BRAF (NM_004333.6) was also common across laboratories on exon 11 (n = 75), exon 15 (n = 86), and p.(Val600Glu) only (n = 59).