Table 1.
The basic characteristics of the enrolled studies
| Study | Year | Country | Ethnicity | Sample size | MFP | M/F | NLR at baseline† |
| Diem S | 2017 | Europe | European | 52 | NM | 29/23 | 5.0 (2.7–8.3)* |
| Bagley SJ | 2017 | America | American | 175 | NM | 80/95 | NLR ≥5:58.0% |
| Russo A | 2018 | Italy | European | 28 | 17 | 25/3 | NM |
| Zer A | 2018 | America | American | 88 | 5.3 | 43/45 | NLR＞4:56.8% |
| Nakaya A | 2018 | Japan | Asian | 101 | 8.9 | 77/24 | NLR ≥3:46.5% |
| Maymani H | 2018 | America | American | 74 | 12.3 | 36/38 | NLR＞6:20.3% |
| Mezquita L | 2018 | Europe | European | 161 | 12 | 100/61 | NLR＞3:39.0% |
| Fukui T | 2018 | Japan | Asian | 52 | 10.9 | 37/15 | NLR ≥5:34.6% |
| Park W | 2018 | America | American | 159 | 11.5 | 82/77 | 4.3 (0.5–24.1)* |
| Takeda T | 2018 | Japan | Asian | 30 | NM | 19/11 | NLR＞5:30.0% |
| Svaton M | 2018 | Czech Republic | European | 120 | NM | 71/49 | NLR＞3.8:50.0% |
| Suh KoungJin | 2018 | Korea | Asian | 54 | 26.2 | 42/12 | NLR＞5:14.8% |
| Shiroyama Takayuki | 2018 | Japan | Asian | 201 | 12.4 | 135/66 | NLR＞4:39.3% |
| Kiriu T | 2018 | Japan | Asian | 19.00 | NM | 19 | NLR＞5:31.6% |
| Khunger M | 2018 | America | American | 109 | 30 | 56/53 | NLR ≥5:50.5% |
| Inomata M | 2018 | Japan | Asian | 36 | NM | 27/9 | NLR ≥5:44.4% |
| Facchinetti F | 2018 | Italy | European | 54 | 12.6 | 45/9 | NM |
| Ren F | 2019 | China | Asian | 147 | 2.6 | 94/53 | NLR＞2.5:59.9% |
| Pavan A | 2019 | Italy | European | 184 | 56.3 | 125/59 | NLR ≥3:57.5% |
| Passiglia F | 2019 | Italy | European | 45 | 9.1 | 32/13 | NLR＞3.3:51.1% |
| Minami S | 2019 | Japan | Asian | 76 | NM | 49/27 | NLR ≥6:14.5% |
| Ichiki Y | 2019 | Japan | Asian | 44 | 4.83 | 38/6 | NM |
| Dusselier M | 2019 | France | European | 59 | NM | 44/15 | NLR＞5:62.7% |
| Study | SCC% | Treatment lines | Outcome | Study design | NOS | Cut-off | IO |
| Diem S | 34.6% | Including first-line therapy | OS/PFS | RO | 6 | 5 | N |
| Bagley SJ | 24.0% | At least second-line therapy | OS/PFS | RO | 6 | 5 | N |
| Russo A | 60.7% | At least second-line therapy | OS/PFS | RO | 7 | 3 | N |
| Zer A | 17.1% | At least second-line therapy | OS/PFS/DCR | RO | 7 | 4 | NM |
| Nakaya A | 36.6% | At least second-line therapy | PFS/irAEs | RO | 6 | 3 | N |
| Maymani H | 16.2% | Including first-line therapy | OS/PFS | RO | 7 | 6 | N/P/D |
| Mezquita L | 28.6% | At least second-line therapy | OS/PFS | RO | 9 | 3 | N/E/A/D |
| Fukui T | 30.8% | At least second-line therapy | OS/PFS/irAEs | PO | 7 | 5 | N |
| Park W | 24.5% | Including first-line therapy | OS/PFS | RO | 7 | 5 | N |
| Takeda T | 30.0% | At least second-line therapy | PFS | RO | 6 | 5 | N |
| Svaton M | 33.3% | At least second-line therapy | OS/PFS | RO | 7 | 3.8 | N |
| Suh KoungJin | 31.5% | Including first line therapy | OS/PFS/irAEs | RO | 8 | 5 | N/P |
| Shiroyama Takayuki | 30.4% | At least second-line therapy | PFS/RR | RO | 7 | 4 | N |
| Kiriu T | 31.5% | At least second-line therapy | OS/PFS/TTF | RO | 7 | 5 | N |
| Khunger M | 23.9% | At least second-line therapy | OS | RO | 6 | 5 | N |
| Inomata M | 44.4% | At least second-line therapy | PFS | RO | 6 | 5 | N/P |
| Facchinetti F | 48.2% | At least second-line therapy | OS/PFS/TTF | PO | 8 | 4 | N |
| Ren F | 42.2% | At least second-line therapy | OS/PFS | RO | 6 | 2.5 | N/P |
| Pavan A | 32.1% | Including first-line therapy | OS/PFS/irAEs | RO | 8 | 3 | N/P/A |
| Passiglia F | 44.4% | At least second-line therapy | OS/TTP | RO | 8 | 3.3 | N |
| Minami S | 23.7% | At least second-line therapy | OS/PFS | RO | 9 | 6 | N/P/A |
| Ichiki Y | 65.9% | Including first-line therapy | OS/PFS/irAEs | RO | 7 | NM | N/P |
| Dusselier M | 20.3% | At least second-line therapy | OS | RO | 8 | 5 | N |
*The study provided only the median NLR and range at baseline.
† The proportion of the patients whose baseline NLR exceeded the cut-off value was provided
A, atezolizumab; D, durvalumab; DCR, disease control rate; E, embrolizumab; IO, immunotherapy; irAEs, immune-related adverse events; M/F, male/female; MFP, median follow-up (months); N, nivolumab; NLR, neutrophil to lymphocyte ratio; NM, not mentioned; NOS, Newcastle-Ottawa quality assessment Scale; OS, overall survival; P, pembrolizumab; PFS, progression-free survival; PO, prospective study; RO, retrospective study; RR, response rate; SCC%, proportion of patients with squamous cell carcinoma; TTF, time to treatment failure; TTP, time to progression.