Summary of the main features of all studies analysed in this systematic review
| Study | Country | Tumour type analysed in the cohort | Number of tumours analysed for MSI | Number of MSI/dMMR (%) | Pancreatic site of MSI/dMMR tumours | Histology of MSI/dMMR tumours | Molecular data of MSI/dMMR tumours | Methodology for MSI analysis IHC PCR NGS | Lynch syndrome | Survival data of MSI/dMMR tumours |
| Han et al11 | Japan, Korea | PC | 9 | 6 (66.6%) | NA | NA | NA | PCR1 | NA | NA |
| Seymour et al12 | USA | PDAC | 7 | 0 (0%) | NA | NA | NA | PCR2 | NA | NA |
| Brentnall et al13 | USA | PC | 13 | 8 (62%) | NA | NA | NA | PCR3 | NA | NA |
| Abe et al14 | Japan | PC | 44 | 7 (15.9%) | NA | NA | NA | PCR4 | NA | NA |
| Venkatasubbarao et al15 | USA | PDAC | 14 | 4 (28.6%) | NA | PDAC G3 | NA | PCR5 | NA | NA |
| Ouyang et al16 | Japan | PC | 60 | 9 (15%) | NA | NA | NA | PCR2 | NA | NA |
| Goggins et al17 | USA | PDAC | 82 | 3 (3.7%) | 3 head (100%) | MED | KRAS wt | PCR6 | NA | 2/3 AWD at 16 and 52 months, 1/3 DOD after 4 months |
| Ghimenti et al18 | Italy | PC | 21 | 0 (0%) | NA | NA | NA | PCR7 | NA | NA |
| Caligo et al19 | Italy | PC | 31 | 13 (42%) | NA | NA | NA | PCR2 | NA | NA |
| Wilentz et al20 | MED | 18 | 4 (22.2%) | NA | MED; 1/4 showed also microglandular features. No associated PanIN | KRAS wt | IHCa, PCR8 | 1 | 3/4 AWD at 13, 24 and 67 months, 1/4 DOD after 4 months | |
| Ueki et al21 | USA | PDAC | 36 | 4 (11.1%)* | NA | MED | 2/4 harboured promoter hypermethylation of hMLH1 | PCR2 | NA | NA |
| Yamamoto et al22 | Japan | PDAC | 103 | 16 (15.5%) | NA | 10/13 PDAC G3, 2 G2, 1 G1 | 10/13 KRAS wt; 11/13 TP53 wt | PCR9 | 3 | MSI associated with better survival |
| Moriyama et al23 | Japan | PDAC | 18 | 2 (11.1%) | NA | NA | NA | PCR10 | NA | NA |
| Nakata et al24 | Japan | PC | 46 | 8 (17.4%) | NA | 5/8 G1, 3 G2-G3-G4 | NA | PCR11 | NA | MSI associated with better survival |
| Tomaszewska et al25 | Poland | PDAC | 30 | 0 (0%) | NA | NA | NA | IHCb | NA | NA |
| Lüttges et al26 | Germany | 11 M/C-C and 12 PDAC | 23 | 1 (4.3%) | 1 head (100%) | M/C-C, pT4 (8 cm) N1 | NA | IHCc, PCR9a | NA | NA |
| Nakata et al27 | Japan | PC | 55 | 4 (7.2%) | 2 head (50%), 1 body (25%), 1 tail (25%) | 2 head: G1; 1 body: G4; 1 tail: G3 | NA | IHCb | NA | Loss of MSH2 associated with initial better survival |
| Maple et al28 | USA | LS-PC | 35 | 3 (8.6%) | NA | 1 MED†, 2 PDAC | Germline MLH1 mutation in 1 patient | IHCc, PCR12 | 1 | NA |
| Fujii et al29 | Japan | PDAC | 21 | 0 (0%) | NA | NA | NA | PCR13 | NA | NA |
| Laghi et al30 | 272 cases Italy, 66 Germany | PDAC | 338 | 1 (0.3%) | Head | G3, pT4N2 | KRAScod12 mutation, BRAF wt | IHCd, PCR9b | No | NA (died of postsurgical complication) |
| Ottenhof et al31 | The Netherlands | PDAC | 78 | 3 (3.9%)‡ | NA | NA | NA | IHCd | NA | NA |
| Mitsuhashi et al32 | Japan | PDAC | 283 | 0 (0%) | NA | NA | NA | PCR14 | NA | NA |
| Riazy et al33 | Canada | PDAC | 265 | 41 (15.4%) | NA | NA | NA | IHCd | NA | dMMR did not correlate with survival§ |
| Grant et al34¶ | Canada | PDAC | 290 | 4 (1.38%) | NA | NA | Germline mutations in 4 patients: 1) MLH1c.677+3A>G; 2, 3) MSH2c.942+3A>T, c.1906g>c; 4) MSH6c.1707delC | NGSa | 4 | NA |
| Connor et al35 | Canada | PDAC | 255 | 4 (1.6%) | NA | NA | NA | IHCd, PCR9a, NGSb | 3 | NA |
| Humphris et al36 | Australia (international cohort) | PDAC | 385 | 4 (1%) | NA | 1 case G4, 2 cases G2, 1 signet ring | All high TMB (100%), 2 KRAS wt (50%) | IHCd, NGSc | No | NA |
| Salem et al37 | USA | PDAC | 870 | 12 (1.4%) | NA | NA | NA | NGSd | No | |
| Lupinacci et al38 | France | PDAC | 513 | 8 (1.6%) | NA | 3pT1, 3pT2, 3pT3; 1 case medullary, 1 colloid, 6 conventional | NA | IHCd, PCR9 | 3 | dMMR did not correlate with survival |
| Wartenberg et al39 | Greece | PDAC | 110 | 5 (4.5%) | NA | Stroma rich in immune cells with a very high stromal CD8/FOXP3 ratio | High prevalence of JAK3 mutations (3/5 cases vs 4/105 MSS PDAC); all KRAS mutated, 2/5 TP53 wt | IHCd | NA | Survival analysis not specific for MSI status |
| Hu et al40 | USA | PDAC | 833 | 7 (0.8%) | NA | 2 conventional, 4 mucinous/colloid IPMN-associated, 1 medullary** | All available for NGS (5 cases) had high TMB | IHCd, PCR9b, NGSe | 7 | dMMR did not correlate with survival |
| Mori et al41 | Japan | PC | 40 | 0 (0%) | NA | NA | NA | PCR15 | NA | NA |
| Latham et al42†† | USA | PDAC | 824 | 34 (4.1%) | NA | NA | 5 patients with germline mutations: 1) MLH1c.1731G.A; p.Ser577Ser; 2) MSH2c.1906G.C; p.Ala636Pro; 3) MSH2c.2038C.T; p.Arg680*; 4) PMS2: deletion exon 11; 5) MSH6c.3268G.T; p.Glu1090* | NGSe | 5 | NA |
| Kato et al43 | Japan | PC | 10 | 0 (0%) | NA | NA | NA | NGSe | NA | NA |
| Singhi et al44 | USA | PDAC | 2563 | 3 (0.1%) | NA | NA | 3 KRAS wt, 1 TP53 wt, 1 case showed the druggable FGFR2-POC1B fusion; 1/3 high TMB; 3 cases harboured KMT2 genes mutations (2 KMT2D and 1 KMT2C) and 2 a JAK1 mutation | NGSf | NA | NA |
| Total | – | – | 8323 | 218 (2.61%) | 7 head, 1 body, 1 tail | 36 conventional PDAC, (3 G4, 16 G3, 5 G2, 8 G1, 4 NOS); 10 MED, 6 MC/C, 1 signet ring | Significant association of MSI/dMMR with KRAS and TP53 wt status and with JAK and KMT2 mutations | – | – | Not significant association with survival |
Microsatellite instability analysis with PCR: 1 PCR with not recommended panel of markers (nor NCI neither MSI PCR): D2S123, D2SI36 and D3S1067; 2 PCR with not recommended panel of markers (nor NCI neither MSI PCR), not further specified; 3 PCR with not recommended panel of markers (nor NCI neither MSI PCR): D2S123, D2S136, D3S1067, D5S107, D6S87, D8S255, D10SI97, D11S904, D17S261, D17S361, D17S787, D18S34; 4 PCR with not recommended panel of markers (nor NCI neither MSI PCR): D1S199, D2S123, D3S1298, TP53, D22S284; 5 PCR with not recommended panel of markers (nor NCI neither MSI PCR): D2S123, D2S136, D3S1067, D5S107, D6S87, D18S34; 6 PCR with not recommended panel of markers (nor NCI neither MSI PCR): BAT26, D10S579, D1OS541, D9S272, D9S258, D9S1809; 7 PCR with not recommended panel of markers (nor NCI neither MSI PCR): D2S313, D2S123, D5S404, D8S255, D10S197, D11S904, D17S250, THRA1, D17S579, D17S396; 8 PCR with not recommended panel of markers (nor NCI neither MSI PCR): length analysis of BAT25 and BAT26 markers; and direct sequencing of the polythymidine tract of the TGFBR2 gene; 9 PCR with NCI / MSI PCR markers: 9a BAT25, BAT26, D2S123, D5S346, D17S250, or 9b BAT25, BAT26, NR-21, NR-24 and NR-27; 10 PCR with not recommended panel of markers (nor NCI neither MSI PCR): D2S123, D3S1067, D9S171, D9S1870, D18S58, D18S46, D18S474; 11 PCR with not recommended panel of markers (nor NCI neither MSI PCR): D2S123, D3S1611, D5S346, D7S501, NM23, TP53-Penta, TP53-Dint and D18S35; 12 PCR with not recommended panel of markers (nor NCI neither MSI PCR): Bat 26, Bat 25, Bat 40, Bat 34c4, D17s250, D5s346, ACTC, D18s55, D10s197 and mycL; 13 PCR with not recommended panel of markers (nor NCI neither MSI PCR): D2S123, D5S107, D10S197, D11S904, D13S175; 14 PCR with not recommended panel of markers (nor NCI neither MSI PCR): BAT25 and BAT26; 15 PCR with not recommended panel of markers (nor NCI neither MSI PCR): MYCL1, D9S242, D8S321, D20S82, D20S85, BAT-25, BAT-26, NR-21, NR-22, NR-25.
Microsatellite instability analysis with IHC: a IHC for MLH1 and MSH2: all MSI cases in this series showed MLH1 loss and MSH2 retained. This study first demonstrated the reliability of IHC in determining MSI in pancreatic cancer; b IHC for MLH1 and MSH2; c IHC for MLH1, MSH2 and MSH6; d IHC for MLH1, PMS2, MSH2 and MSH6.
Microsatellite instability analysis with NGS: a NGS using a custom panel targeting the exonic and splice site regions of 385 genes previously associated with cancer; b Whole-genome sequencing variant calls, RNA sequencing and microarray expression values available from the International Cancer Genome Consortium data portal; c NGS with ‘MSI sensor’ methodology; d MSI-NGS assessment with the reference genome hg19 from the University of California, Santa Cruz—‘Genome Browser database’; e MSK-IMPACT panel, ‘MSI sensor’ methodology; f Illumina HiSeq technology, MSI tested using 114 loci.
*In this study, 4 out of 36 cases were MSI, but these cases were specifically and deliberately added by authors to expand the spectrum of cases to be studied for hypermethylation; in addition, 3 of the 4 MSI tumours were previously reported by Goggins et al.
†First reported case of medullary phenotype associated with MSH2 loss (previously reported cases were all MLH1 negative).
‡Data obtained from another manuscript (Lupinacci et al48), two cases were MSH2-MSH6 negative, and one case was PMS2-MLH1 negative.
§dMMR had no survival advantage from gemcitabine or 5-fluorouracil adjuvant chemotherapy.
¶This study investigated germline mutations.
**This case is probably a medullary PDAC (described as a poorly differentiated carcinoma with fused glands and some necrotic areas).
††This study investigated >50 cancer types, with patients with PDAC representing 5.5% of the entire cohort.
AWD, alive without disease; dMMR, defective mismatch repair; DOD, died of disease; IHC, immunohistochemistry; LS-PC, long survivors-pancreatic cancer (>36 months after surgery); M/C-C, mucinous/colloid carcinoma of the pancreas; MED, medullary pancreatic cancer;MN, mononucleotide marker; MSI, microsatellite instability; NA, not assessed (or not reported); NGS, next-generation sequencing; PC, pancreatic cancer, not otherwise specified; PCR, polymerase chain reaction; PDAC, pancreatic ductal adenocarcinoma; TMB, tumour mutation burden; wt, wild type.