Table 2.
Association of pigmentary phenotype with melanoma risk in the Australian Melanoma Family Study and Leeds case–control study
| Pigmentary phenotype† | Australia (N = 1112) | Leeds (N = 2516) | P‐int¶ | ||||||
|---|---|---|---|---|---|---|---|---|---|
|
Case N (%) |
Control N (%) |
OR (95% CI)‡ | Adjusted OR (95% CI)§ |
Case N (%) |
Control N (%) |
OR (95% CI)‡ | Adjusted OR (95% CI)§ | ||
| Hair colour | |||||||||
| Dark brown/black | 160 (26) | 200 (40) | 1.00 | 1.00 | 822 (41) | 288 (57) | 1.00 | 1.00 | 0.37 |
| Light brown | 244 (40) | 208 (42) | 1.41 (1.05, 1.88) | 1.26 (0.93, 1.70) | 537 (27) | 119 (24) | 1.62 (1.27, 2.06) | 1.61 (1.25, 2.06) | |
| Fair or Blonde | 142 (23) | 64 (13) | 2.64 (1.82, 3.84) | 2.38 (1.61, 3.51) | 398 (20) | 68 (13) | 2.05 (1.54, 2.75) | 1.99 (1.48, 2.69) | |
| Red | 70 (11) | 24 (5) | 3.41 (2.03, 5.75) | 4.21 (2.44, 7.27) | 253 (13) | 29 (6) | 3.10 (2.06, 4.66) | 3.01 (1.99, 4.57) | |
| Eye colour | |||||||||
| Brown or Black | 111 (18) | 119 (24) | 1.00 | 1.00 | 322 (16) | 94 (19) | 1.00 | 1.00 | 0.62 |
| Green or Hazel | 224 (36) | 167 (34) | 1.52 (1.08, 2.13) | 1.35 (0.95, 1.93) | 605 (30) | 182 (36) | 0.98 (0.73, 1.30) | 0.97 (0.72, 1.30) | |
| Blue or Grey | 279 (45) | 206 (42) | 1.57 (1.13, 2.17) | 1.49 (1.06, 2.09) | 1075 (54) | 228 (45) | 1.40 (1.07, 1.84) | 1.40 (1.06, 1.85) | |
| Skin colour | |||||||||
| Olive or Brown | 62 (10) | 92 (19) | 1.00 | 1.00 | 149 (7) | 60 (12) | 1.00 | 1.00 | 0.30 |
| Fair | 430 (70) | 336 (68) | 1.92 (1.33, 2.76) | 1.75 (1.20, 2.55) | 1342 (67) | 365 (72) | 1.51 (1.09, 2.08) | 1.48 (1.06, 2.08) | |
| Very fair | 119 (19) | 67 (14) | 2.33 (1.48, 3.66) | 2.29 (1.42, 3.68) | 519 (26) | 79 (16) | 2.63 (1.79, 3.86) | 2.54 (1.71, 3.79) | |
| Freckles in childhood | |||||||||
| None | 116 (19) | 127 (26) | 1.00 | 1.00 | 543 (28) | 187 (37) | 1.00 | 1.00 | 0.28 |
| Very few | 185 (30) | 163 (33) | 1.17 (0.83, 1.64) | 1.17 (0.82, 1.66) | 571 (29) | 131 (26) | 1.46 (1.13, 1.89) | 1.33 (1.02, 1.73) | |
| Few/Some | 244 (40) | 156 (32) | 1.56 (1.12, 2.18) | 1.69 (1.19, 2.39) | 698 (35) | 159 (32) | 1.48 (1.15, 1.89) | 1.35 (1.05, 1.75) | |
| Many | 69 (11) | 48 (10) | 1.41 (0.89, 2.24) | 1.55 (0.95, 2.52) | 161 (8) | 26 (5) | 2.11 (1.34, 3.31) | 2.06 (1.30, 3.29) | |
| Freckles in adulthood | |||||||||
| None | 160 (26) | 156 (32) | 1.00 | 1.00 | 654 (33) | 209 (42) | 1.00 | 1.00 | 0.38 |
| Very few | 238 (39) | 200 (40) | 1.07 (0.79, 1.45) | 1.03 (0.75, 1.40) | 630 (31) | 132 (26) | 1.51 (1.17, 1.93) | 1.38 (1.07, 1.78) | |
| Few/Some | 175 (28) | 119 (24) | 1.25 (0.89, 1.75) | 1.24 (0.87, 1.77) | 609 (30) | 144 (29) | 1.35 (1.05, 1.73) | 1.22 (0.94, 1.58) | |
| Many | 42 (7) | 20 (4) | 1.62 (0.89, 2.95) | 1.67 (0.89, 3.13) | 108 (5) | 18 (4) | 1.87 (1.10, 3.18) | 1.83 (1.06, 3.16) | |
| General skin reaction to sun (skin phototype) | |||||||||
| Sometimes/Never Burns | 290 (47) | 292 (59) | 1.00 | 1.00 | 1276 (64) | 375 (75) | 1.00 | 1.00 | 0.88 |
| Usually/Always Burns | 322 (53) | 200 (41) | 1.55 (1.21, 1.99) | 1.60 (1.23, 2.09) | 726 (36) | 127 (25) | 1.69 (1.36, 2.11) | 1.62 (1.28, 2.04) | |
| Ability to tan from repeated exposure | |||||||||
| Moderate/Deep Tan | 359 (59) | 331 (67) | 1.00 | 1.00 | 542 (53) | 336 (67) | 1.00 | 1.00 | 0.13 |
| Mild/No Tan | 254 (41) | 162 (33) | 1.32 (1.02, 1.70) | 1.33 (1.01, 1.74) | 484 (47) | 163 (33) | 1.85 (1.48, 2.33) | 1.88 (1.48, 2.39) | |
| Propensity to sunburn | |||||||||
| Mild/No burn | 222 (36) | 242 (49) | 1.00 | 1.00 | 606 (59) | 343 (69) | 1.00 | 1.00 | 0.44 |
| Severe/Painful burn | 392 (64) | 252 (51) | 1.68 (1.31, 2.16) | 1.69 (1.30, 2.20) | 418 (41) | 157 (31) | 1.51 (1.20, 1.89) | 1.47 (1.16, 1.86) | |
| Clinically assessed hair colour | |||||||||
| Black/Brown | 176 (39) | 172 (57) | 1.00 | 1.00 | 424 (68) | 217 (84) | 1.00 | 1.00 | 0.55 |
| Fair/Blonde | 195 (43) | 109 (36) | 1.59 (1.15, 2.20) | 1.48 (1.05, 2.08) | 102 (16) | 25 (10) | 2.09 (1.31, 3.34) | 2.14 (1.31, 3.49) | |
| Red | 82 (18) | 21 (7) | 3.27 (1.90, 5.60) | 3.58 (2.05, 6.27) | 93 (15) | 16 (6) | 2.90 (1.66, 5.07) | 3.19 (1.79, 5.66) | |
| Clinically assessed eye colour | |||||||||
| Brown | 87 (19) | 68 (23) | 1.00 | 1.00 | 101 (11) | 77 (15) | 1.00 | 1.00 | 0.44 |
| Green/Hazel | 132 (29) | 94 (31) | 1.11 (0.72, 1.71) | 1.06 (0.68, 1.65) | 332 (35) | 195 (39) | 1.35 (0.95, 1.91) | 1.31 (0.91, 1.88) | |
| Blue/Grey | 231 (51) | 140 (46) | 1.44 (0.97, 2.14) | 1.43 (0.95, 2.16) | 515 (54) | 229 (46) | 1.85 (1.31, 2.59) | 1.83 (1.29, 2.60) | |
| Pigmentation score †† | |||||||||
| Tertile 1 | 120 (20) | 153 (31) | 1.00 | 1.00 | 483 (25) | 190 (38) | 1.00 | 1.00 | 0.32 |
| Tertile 2 | 188 (31) | 145 (30) | 1.55 (1.10, 2.18) | 1.57 (1.11, 2.22) | 629 (32) | 170 (34) | 1.40 (1.10, 1.80) | 1.36 (1.06, 1.75) | |
| Tertile 3 | 296 (49) | 188 (39) | 1.83 (1.32, 2.52) | 1.92 (1.38, 2.67) | 839 (43) | 141 (28) | 2.40 (1.86, 3.10) | 2.17 (1.67, 2.82) | |
CI, confidence interval; OR, odds ratio.
Missing data for each variable (N for Australia, N for Leeds): hair colour (0, 2), eye colour (6, 10), skin colour (6, 2), freckling child (4, 40), freckling adult (2, 12), skin reaction to sun (8, 12), skin often exposed (6, 991), skin exposed (4, 992), clinically assessed hair colour (357, 1639), clinically assessed eye colour (360, 1067) and pigmentation score (22, 64).
†Phenotype variables were based on self‐report unless specified as clinically assessed.
‡Minimally adjusted models adjusted for age (continuous), sex and city of recruitment in Australia.
§Further adjusted for self‐reported naevus density, summer holiday sun exposure hours per day and painful sunburns to 40 years of age.
¶P‐value for the interaction between pigmentary phenotype variable and country (Australia/Leeds) using minimally adjusted models.
††Based on factor analysis (see Supplementary online material). Tertile cut‐points were based on the combined Australia/Leeds control distributions.