5. Details of articles describing a single method.
| Author (year) | Country of population/cohort | Length of follow‐up (median in months (range)) | Number of participants | Tumour type | IDH mutation status (% of WT) | Technique used to assess MGMT methylation status |
| Abhinav 2013 | UK | NR | 19 | GBM | NR | MSP |
| Adeberg 2015 | Germany | NR | 32 | GBM | NR | MSP |
| Ahmed 2015 | US | 11.4 | 214 | GBM | NR | mRNA levels |
| Alonso 2017 | Spain | NR | 63 | GBM: 97.2%; gliosarcoma: 2.8% | 88.7 (data from 63/71 people) | MSP |
| Appin 2013 | US | NR | 236 | GBM: primary: 89% (GBM with oligodendroglioma: 13.3%); secondary: 11% | GBM: 91.4 (data from 116/208 people); GBM‐O: 65 (data from 20/28 people) | MSP |
| Ardon 2012 | Belgium | 25.0 (10.5–42.2) | 77 | GBM (primary) | NR | MSP |
| Arita 2016 | Japan | NDR | 193 | GBM | 100 | PSQ |
| Badruddoja 2017 | US | NR | 30 | GBM | NR | qMSP |
| Balana 2016 | Spain | NR | 93 | GBM | NR | MSP |
| Balana 2017 | Spain | 17.0 (10.7–24.5) | 256 | GBM | 94.5 (data from 162/256 people) | MSP |
| Blumenthal 2017 | US | NR | 1395 | GBM | NR | qMSP |
| Boots‐Sprenger 2013 | The Netherlands | NR | 333 | GBM | 84 (data from 226/333 people) | MS‐MLPA |
| Brandes 2008 | Italy | 18.93 (6.6–62) | 208 | GBM | NR | MSP |
| Brandes 2009 | Italy | NR | 37 | GBM | NR | MSP |
| Brandes 2010 | Italy | NR | 44 | GBM | NR | MSP |
| Brandes 2014 | Italy | NR | 116 | GBM | NR | MSP |
| Brandes 2017 | Italy | NR | 108 | GBM | NR | MSP |
| Brennan 2013 | US | NR | 332 | GBM | 93.4 (data from 423/543 people) | Bead array |
| Burford 2013 | UK | NR | NDR | GBM | NDR | MSP |
| Burger 2017 | Germany | NR | 32 | GBM | NR | MSP |
| Butowski 2011 | US | NR | 66 | GBM and gliosarcoma | NR | MSP |
| Capellades 2018 | Spain | NR | 292 | GBM | 96.6 | MSP |
| Chakhoyan 2018 | US | NR | 23 | GBM | NR | MSP |
| Chen 2015 | China | 12.8 (4.0–37.7) | 78 | GBM | NR | IHC |
| Chen 2016 | China | NR | 300 | GBM | 85.7 | Bead array |
| Cheng 2015 | China, US | NR | 285 (CGGA: 55; TCGA: 235) | GBM | NR | Bead array (TCGA); PSQ (CGGA) |
| Chinot 2007 | France | 6 (0.9–19) | 29 | GBM | NR | IHC |
| Choi 2016 | South Korea | NR | 112 (training cohort: 74; test cohort 38) | GBM | NR | MSP |
| Clarke 2009 | US | 18.8 | 85 | GBM | NR | MSP |
| Coburger 2017 | Germany | 40 (37–43) | 170 | GBM | NR | MSP |
| Colman 2010 | US | NR | 101 | GBM | NR | qMSP |
| Combs 2011 | Germany | NR | 160 | GBM (primary) | 97.1 (data from 140/160 people) | MSP |
| Cominelli 2015 | Italy | NR | 70 | GBM | 95.7 | MSP |
| Costa 2010 | Portugal | NR | 90 | GBM (primary) | NR | MSP |
| Criniere 2007 | France | 57.2 | 77 | GBM | NR | MSP |
| Dahlrot 2017 | Denmark | NR | 226 | GBM (primary) | NR | PSQ |
| Das 2011 | India | NR | 6 | GBM | NR | MSP |
| Etcheverry 2014 | France | 15.5 | 399 | GBM (primary) | 91 | PSQ |
| Felsberg 2011 | Germany | 48.6 | 64 | GBM | NR | MSP |
| Fiano 2014 | Italy | NR | 32 | GBM | NR | MSP |
| Fontana 2016 | Italy | NDR | 128 | GBM | NDR | PSQ |
| Franceschi 2016 | Italy | NR | 21 | GBM | NR | MSP |
| Franceschi 2018 | Italy | NR | 169 | GBM | NR | MSP |
| Galldiks 2015 | Germany | NR | 21 | GBM | NR | MSP |
| Gallego Perez‐Larraya 2011 | France | NR | 31 | GBM | NR | qMSP |
| Gilbert 2013 | Canada, European multicentres, US | NR | 762 | GBM | NR | qMSP |
| Gilbert 2014 | Canada, European multicentres, US | NR | 637 | GBM | NR | qMSP |
| Gittleman 2017 | US | NR | 799 | GBM | NR | qMSP |
| Glas 2009 | Germany | 41.5 | 23 | GBM | NR | MSP |
| Gorlia 2008 | Belgium, Canada, Italy, Germany, Switzerland, the Netherlands | NR | 287 | GBM | NR | MSP |
| Gramatzki 2016 | Switzerland | 9 | 108 | GBM | 100 | MSP |
| Gutenberg 2013a | Germany | NR | 17 | GBM (primary) | NR | MSP |
| Gutenberg 2013b | Germany | 16.2 (1.4–54.1) | 191 | GBM (primary) | NR | MSP |
| Ha 2013 | South Korea | NR | 10 | GBM | 75 | qMSP |
| Haemmig 2014 | Switzerland | NR | 60 | GBM | 85 | qMSP |
| Han 2014 | US | NR | 28 | GBM | NR | MSP |
| Han 2015a | China | 13.7 (1–43) | 152 | GBM | NR | MSP |
| Han 2015b | China | 13.7 (1–43) | 79 | GBM | 93.5 (data from 214 people) | MS‐MLPA |
| Happold 2018 | European multicentres | 29 (25–35; CENTRIC cohort) | 797 | GBM | NR | qMSP |
| Hayes 2015 | US | 14.1 | 219 | GBM | 94.5 (data from 475 people) | Bead array |
| Hegi 2004 | Switzerland | NR | 38 | GBM | NR | MSP |
| Hegi 2005 | Canada, European multicentres | NR | 106 | GBM | NR | MSP |
| Herrlinger 2006 | Germany | NR | 31 | GBM | NR | MSP |
| Herrlinger 2009 | Germany | 41.5 | 31 | GBM | NR | MSP |
| Hervouet 2009 | France | NR | 53 | GBM | NR | MSP |
| Hobbs 2012 | US | 19.1 (8.1–74.6; survivors only) | 312 | GBM | NR | qMSP |
| Huang 2017 | US | NR | 301 | GBM | NR | mRNA levels |
| Hudson 2018 | Australia | NR | 16 | GBM | NR | PSQ |
| Inoges 2017 | Spain | NR | 31 | GBM | NR | MSP |
| Ishida 2015 | Japan | NR | 46 | GBM | NR | IHC |
| Ishikawa 2014 | Japan | 19.6 (7.3–48.7) | 23 | GBM | 75 (data from the whole cohort) | IHC |
| Ius 2018 | Italy | NR | 116 | GBM | NR | PSQ |
| Iwadate 2017 | Japan | NR | 70 | GBM | 92 | IHC |
| Jan 2018 | Taiwan | NR | NDR | GBM | NDR | MSP |
| Karim 2012 | Egypt | NR | 34 | GBM | NR | MSP |
| Kessler 2018 | Germany, US | NR | 404 (Heidelberg cohort: 143; TCGA: 261) | GBM | 100 | Bead array |
| Kim 2012 | South Korea | 22 (3–88) | 93 | GBM | NR | MSP |
| Kim 2017 | South Korea | 16.3 (0.3–105.1) | 750 | GBM | NR | MSP |
| Kim 2018 | South Korea | NR | 93 | GBM | 86.8 (data from 91 people) | qMSP |
| Klitkou 2014a | Denmark | NR | 173 | GBM (primary) | NR | IHC |
| Klitkou 2014b | Denmark | NR | 173 | GBM (primary) | NR | IHC |
| Klitkou 2014c | Denmark | NR | 173 | GBM (primary) | NR | IHC |
| Kong 2011 | South Korea | 16.5 (6.2–48) | 90 | GBM | NR | MSP |
| Kreth 2013 | Germany | NR | 222 | GBM | NR | MSP |
| Lakomy 2011 | Czech Republic | NR | 38 | GBM | NR | PCR‐HRM |
| Laxton 2013 | UK | NR | 288 | GBM | 95.3 (data from 107/288 people) | MSP |
| Lee 2013 | South Korea | 15 | 36 | GBM | NR | qMSP |
| Lee 2017 | South Korea | NR | 65 | GBM | 80 | MSP |
| Li 2016a | China | NR | 145 | GBM | 83.4 | MSP |
| Li 2016b | China | NR | 50 | GBM (primary) | 85.9 (data from 50/78 people) | PSQ |
| Lombardi 2015 | Italy | NR | 151 | GBM | 94 (data from 100/237 people) | MSP and PSQ |
| Lombardi 2017 | Italy | NR | 128 | GBM | NR | PSQ |
| Ma 2016 | China | NR | 56 | GBM (primary) | NR | MSP |
| Majewska 2017 | United Kingdom | NR | 99 | GBM | NR | PSQ |
| Malmström 2012 | Austria, Denmark, France, Norway, Sweden, Switzerland, Turkey | NR | 72 | GBM | 99.7 (data from 291 people) | qMSP |
| Malmström 2017 | Denmark, Finland, Norway, Sweden | 20 | 78 | GBM | 96.10% | PSQ |
| Martini 2008 | Italy | NR | 46 | GBM | NR | MSP |
| McDonald 2015 | Australia | NR | 33 | GBM | 93.90% | PSQ |
| Metellus 2011 | France | 18.9 | 61 | GBM | NR | qMSP |
| Meyronet 2017 | Austria, Denmark, France, Norway, Sweden, Switzerland, Turkey | NR | 6 | GBM | 100 | PSQ |
| Michaelsen 2013 | Denmark | 60 (23–92) | 163 | GBM | NR | IHC |
| Michaelsen 2018 | Denmark | NR | 415 | GBM | 100 | mRNA levels |
| Minniti 2011a | Italy | NR | 36 | GBM (recurrent) | NR | MSP |
| Minniti 2011b | Italy | NR | 83 | GBM | NR | MSP |
| Minniti 2015 | Italy | 24.0 (standard RT + TMZ group); 22.5 (short course RT + TMZ group) | 243 | GBM | NR | MSP |
| Miyazaki 2014 | Japan | NR | 117 | GBM: 83.8%; GBM with oligodendroglioma: 16.2% | 93.4 | IHC |
| Montano 2011 | Italy | NR | 73 | GBM (primary) | NR | MSP |
| Morandi 2010 | Italy | NR | 159 | GBM | NR | qMSP |
| Motomura 2011 | Japan | 16.7 (3.4–46.7) | 68 | GBM (primary) | 94.1 | PSQ |
| Mur 2015 | Spain | NR | 68 | GBM | 70.6 (unknown in 25%) | Bead array |
| Nabors 2012 | US | NR | 69 | GBM | NR | qMSP |
| Nagane 2007 | Japan | 7.1 (2.4–16.7) | 19 | GBM (recurrent) | NR | Western blot analysis |
| Ohka 2011 | Japan | NR | 51 | GBM (primary) | 94 | PSQ |
| Ohno 2013 | Japan | NR | 85 | GBM | NR | PSQ |
| Ohno 2016 | Japan | NR | 112 | GBM | 92 | PSQ |
| Omuro 2014 | US | 42 | 40 | GBM | 100 | qMSP |
| Pallini 2008 | Italy | NR | 44 | GBM | NR | MSP |
| Pambuku 2016 | Italy | NR | 128 | GBM | NR | PSQ |
| Park 2013 | South Korea | NR | 75 | GBM | NR | MSP |
| Pei 2013 | China | NR | 54 | GBM | NR | MSP |
| Picart 2018 | France | NR | 14 | GBM (cerebellar) | 100 | PSQ |
| Poulsen 2017 | Denmark | 14 | 146 | GBM | 98 | IHC |
| Prados 2009 | US | 33.7 | 65 | GBM and gliosarcoma | NR | MSP |
| Purkait 2016 | India | NR | 114 | GBM | 93.3 | MSP |
| Qi 2012 | China | NR | 86 | GBM (secondary) | 26.6 (data from 79 people) | MSP |
| Rankeillor 2014 | UK | NR | 29 | GBM (primary) | NR | MS‐MLPA |
| Rapkins 2015 | Australia, US | NR | 319 (AGOG cohort: 160; UCLA cohort: 159) | GBM | NR | MSP (UCLA); PSQ (AGOG) |
| Rapp 2013 | Germany | NR | 85 | GBM (primary) | NR | MSP |
| Reifenberger 2012 | Germany | 29 | 104 | GBM | NR | MSP |
| Roh 2017 | South Korea | 20.8 | 252 | GBM: 84.5%; giant‐cells GBM: 4.0%; GBM with oligodendroglioma: 11.5% | 93.4 (data from 106/252 people) | MSP |
| Romano 2013 | Italy | NR | 47 | GBM | NR | MSP |
| Rosati 2013 | Italy | 11.5 (1.5–58) | 83 | GBM: 95.2%; gliosarcoma: 2.4%; GBM with oligodendroglia: 2.4% | 97.6 | MSP |
| Rosenschold 2019 | Denmark | NR | 412 | GBM (primary) | NR | IHC |
| Rubio Fernandez 2014 | Spain | NR | 65 | GBM | NR | MSP |
| Sadones 2009 | Belgium | NR | 32 | GBM (recurrent) | NR | qMSP |
| Saito 2017a | Japan | NR | 53 | GBM (supratentorial) | 49 (unknown in 49%) | IHC |
| Saito 2017b | Japan | NR | 36 | GBM (supratentorial) | NR | IHC |
| Saito 2018a | Japan | NR | 102 | GBM (supratentorial) | 75.5 | IHC |
| Saito 2018b | Japan | NR | 50 | GBM (supratentorial) | 100 | IHC |
| Saito 2018c | Japan | NR | 50 | GBM (supratentorial) | NR | IHC |
| Salvati 2012 | Italy | NR | 105 | GBM (primary supratentorial) | NR | MSP |
| Sana 2014 | Czech Republic | NR | 58 | GBM (primary) | NR | PCR‐HRM |
| Saraiva‐Esperon 2014 | Spain | NR | 25 | GBM | NR | MSP |
| Sasaki 2018 | Japan | NR | 101 | GBM: 99%; gliosarcoma: 1% | 99 | qMSP |
| Schaich 2009 | Germany | NR | 64 | GBM (supratentorial) | NR | MSP |
| Schiffgens 2016 | Germany, Italy | NR | 225 (Hannover cohort 1: 120); Bologna cohort: 105) | GBM (primary) | 91.4 (data from the Bologna cohort) | MSP |
| Schulze Heuling 2017 | Germany, US | NR | 275 | GBM | 100 | Bead array |
| Shu 2018 | China | NR | 265 | GBM (primary) | 100 | PSQ |
| Sijben 2008 | Canada | NR | 16 | GBM (supratentorial) | NR | MSP |
| Singh 2012 | India | 13.15 (1.5–46) | 16 | Gliosarcoma | NR | MSP |
| Soike 2018 | US | NR | 74 | GBM | 89.2 | IHC |
| Stetson 2016 | US | NR | 203 (training cohort: 102; validation cohort: 101) | GBM | Training cohort: 75 (unknown: 21%); validation cohort: 77 (unknown: 17%) | Bead array |
| Stummer 2012 | Germany | 24 | 143 | GBM | NR | MSP |
| Stupp 2009 | Canada, European multicentres | 61 (0.36–79) | 287 | GBM | NR | MSP |
| Stupp 2010 | Germany, Switzerland | 34 | 52 | GBM | NR | MSP |
| Suchorska 2015 | Germany | NR | 79 | GBM (supratentorial) | NR | MSP |
| Tanaka 2014 | Japan | NR | 45 | GBM | NR | mRNA levels |
| Thon 2011 | Germany | 11 (5–33) | 56 | GBM | NR | MSP |
| Tini 2015 | Italy | NR | 144 | GBM | NR | MSP |
| Tini 2016 | Italy | 12 (6–84) | 169 | GBM | 100 | MSP |
| Tini 2017 | Italy | NR | 222 | GBM | NR | MSP |
| Toms 2018 | Multicentre (North America, Europe, South Korea, Israel) | NR | 466 | GBM (supratentorial) | NR | MSP |
| Trabelsi 2016 | Tunisia | NR | 20 | GBM | NR | MS‐MLPA |
| Urbschat 2017 | Germany | NR | 72 | GBM | NR | MSP |
| van Dijken 2019 | China, Taiwan, the Netherland, UK | NR | 50 | GBM | 84 (missing in 8%) | PSQ |
| Villani 2015 | Italy | 12 (3–27) | 51 | GBM (primary) | NR | PSQ |
| Wang 2014 | China | 47 (6–65) | 78 | GBM | 52.6 | MSP |
| Wang 2015a | China | NR | 216 | GBM | 48.1 | MSP |
| Wang 2015b | Multicentre (North America and Europe) | 31.9 (0.2–53.3) | 831 | GBM | NR | qMSP |
| Wang 2016 | China, US | NR | 84 (CGGA: 21; TCGA: 63) | GBM | NR | Bead array (TCGA); PSQ (CGGA) |
| Watanabe 2011 | Japan | 15.4 | 41 | GBM | NR | IHC |
| Wee 2017 | South Korea | 20.5 | 340 | GBM | 93.8 | MSP |
| Wee 2018 | Japan, South Korea | 18.4 | 692 | GBM | 92.3 | MSP |
| Wei 2017 | Taiwan | NR | 25 | GBM | NR | PSQ |
| Weller 2015 | Austria, Germany, Switzerland | NR | 105 | GBM (recurrent) | NR | MSP |
| Weller 2017b | Multicentre (165 hospitals in 22 countries) | NR | 745 | GBM (EGFRvIII‐expressing) | NR | MSP |
| Weller 2009 | Germany | 29.4 (data from the whole cohort) | 189 | GBM: 96.7; giant cells GBM: 2.6%; gliosarcoma: 0.75 | 94.4 (data from the whole cohort) | MSP |
| Westphal 2015 | Germany | NR | 66 | GBM | NR | PSQ |
| Wu 2018 | US | NR | 285 | GBM | NR | Bead array |
| Yan 2017 | UK | NR | 31 | GBM | 90.3 | PSQ |
| Yang 2015 | China | NR | 229 | GBM | 76.3 (data from 274 people; unknown in 3.3%) | PSQ |
| Yin 2017 | France | NR | 106 | GBM | NR | Bead array |
| Yin 2018 | France | 53 (8–113; Rennes and Angers datasets) | 129 | GBM | NR | Bead array |
| You 2013 | Taiwan | NR | 32 | GBM | NR | qMSP |
| Younis 2016 | Egypt | 13 (9–27) | 73 | GBM | NR | IHC |
| Yuan 2017a | China | NR | 84 | GBM | NR | PSQ |
| Yuan 2017b | China | NR | 48 | GBM | NR | PSQ |
| Yue 2014 | China | 17.5 (3–77) | 62 | GBM | NR | IHC |
| Zhang 2014 | China | NR | 80 | GBM | NR | PCR‐HRM |
| Zunarelli 2011 | Italy | 10.9 | 46 | GBM (primary) | NR | MSP |
EGFRvIII: epidermal growth factor receptor variant 3; GBM: glioblastoma; IDH: isocitrate dehydrogenase; IHC: immunohistochemistry; MGMT: O6‐methylguanine–DNA methyltransferase; mRNA: messenger ribonucleic acid; MS‐MLPA: methylation‐specific multiplex ligation‐dependent probe amplification; MSP: methylation‐specific polymerase chain reaction; NDR: not directly reported; NR: not reported; PCR‐HRM: polymerase chain reaction with high‐resolution melting; PSQ: pyrosequencing; qMSP: quantitative methylation‐specific polymerase chain reaction; RT: radiotherapy; TMZ: temozolomide; WT: wild‐type.