Variables | Totala, no. (%) | PORT, .no (%) | No PORT, .no. (%) | P value |
---|---|---|---|---|
Total No. of events | 2771 | 1042 | 1729 | Â |
Median follow-up time, months (IQR) | 217(137, 311) | 197 (125, 269) | 235 (146, 339) |  < 0.001 |
Age at diagnosis, year |  |  |  |  < 0.001 |
 0–35 | 641(23.1) | 183(28.5) | 458(71.5) |  |
  > 35 | 2130(76.9) | 859(40.3) | 1271(59.7) |  |
 Race |  |  |  |  < 0.001 |
 White | 2417(87.2) | 867(35.9) | 1550(64.1) |  |
 Black | 197(7.1) | 114(57.9) | 83(42.1) |  |
Other‡ | 131(4.7) | 57(43.5) | 74(56.5) |  |
Unknown | 26(0.9) | 4(15.4) | 22(84.6) | Â |
Sex | Â | Â | Â | 0.772 |
 Female | 740(26.7) | 275(37.2) | 465(62.8) |  |
 Male | 2031(73.3) | 767(37.8) | 1264(62.2) |  |
Year of diagnosis |  |  |  |  < 0.001 |
 1975–2000 | 1871(67.5) | 646(34.5) | 1225(65.5) |  |
 2001–2018 | 900(32.5) | 396(44.0) | 504(56.0) |  |
Site of index HNSCC |  |  |  |  < 0.001 |
 Oral cavity | 1876(67.7) | 420(22.4) | 1456(77.6) |  |
 Oropharynx | 383(13.8) | 323(84.3) | 60(15.7) |  |
 Larynx | 490(17.7) | 281(57.3) | 209(42.7) |  |
Hypopharynx | 22(0.8) | 18(81.8) | 4(18.2) | Â |
Stage of index HNSCC | Â | Â | Â | Â |
 Localized | 1681(60.7) | 320(19.0) | 1361(81.0) |  < 0.001 |
 Regional | 949(34.2) | 669(70.5) | 280(29.5) |  |
 Unknown | 141(5.1) | 53(37.6) | 88(62.4) |  |
Development of SPMs | Â | Â | Â | 0.322 |
 No | 2177(78.6) | 829(38.1) | 1348(61.9) |  |
 Yes | 594(21.4) | 213(35.9) | 381(64.1) |  |
Median follow-up time at event (any SPMs), months (IQR) | 173(111, 253) | 166(47.7) | 182(52.3) |  < 0.001 |