TABLE 3.
HRs and 95% CIs of squamous cell carcinoma according to quintiles of cumulative updated furocoumarin intake in the NHS and HPFS1
| Intake quintiles | |||||||
|---|---|---|---|---|---|---|---|
| Q1 | Q2 | Q3 | Q4 | Q5 | P-trend | ||
| Total furocoumarins | |||||||
| NHS | Cases, n | 366 | 440 | 448 | 437 | 531 | |
| Age-adjusted HR | 1.00 (referent) | 1.16 (1.01, 1.34) | 1.17 (1.01, 1.34) | 1.10 (0.96, 1.27) | 1.28 (1.12, 1.47) | 0.002 | |
| Multivariable-adjusted HR | 1.00 (referent) | 1.11 (0.97, 1.28) | 1.10 (0.95, 1.26) | 1.03 (0.89, 1.18) | 1.18 (1.03, 1.36) | 0.04 | |
| HPFS | Cases, n | 278 | 393 | 376 | 411 | 386 | |
| Age-adjusted HR | 1.00 (referent) | 1.34 (1.15, 1.56) | 1.28 (1.10, 1.50) | 1.35 (1.16, 1.57) | 1.19 (1.02, 1.40) | 0.70 | |
| Multivariable-adjusted HR | 1.00 (referent) | 1.19 (1.02, 1.39) | 1.16 (0.99, 1.36) | 1.23 (1.05, 1.43) | 1.13 (0.97, 1.33) | 0.54 | |
| Pooled2 | Multivariable-adjusted HR | 1.00 (referent) | 1.14 (1.03, 1.27) | 1.12 (1.01, 1.25) | 1.12 (0.94, 1.33) | 1.16 (1.05, 1.29) | 0.15 |
| Bergaptol | |||||||
| NHS | Cases, n | 395 | 447 | 443 | 454 | 483 | |
| Age-adjusted HR | 1.00 (referent) | 1.22 (1.06, 1.40) | 1.10 (0.96, 1.26) | 1.15 (1.00, 1.31) | 1.20 (1.05, 1.38) | 0.10 | |
| Multivariable-adjusted HR | 1.00 (referent) | 1.18 (1.03, 1.36) | 1.04 (0.91, 1.20) | 1.08 (0.95, 1.24) | 1.12 (0.98, 1.28) | 0.49 | |
| HPFS | Cases, n | 318 | 371 | 389 | 410 | 356 | |
| Age-adjusted HR | 1.00 (referent) | 1.28 (1.10, 1.49) | 1.21 (1.04, 1.41) | 1.29 (1.11, 1.49) | 1.13 (0.97, 1.32) | 0.71 | |
| Multivariable-adjusted HR | 1.00 (referent) | 1.18 (1.01, 1.37) | 1.09 (0.93, 1.26) | 1.17 (1.01, 1.36) | 1.08 (0.92, 1.25) | 0.85 | |
| Pooled2 | Multivariable-adjusted HR | 1.00 (referent) | 1.18 (1.07, 1.31) | 1.06 (0.96, 1.18) | 1.12 (1.02, 1.24) | 1.10 (0.99, 1.21) | 0.72 |
| Bergapten | |||||||
| NHS | Cases, n | 394 | 434 | 432 | 471 | 491 | |
| Age-adjusted HR | 1.00 (referent) | 1.04 (0.91, 1.20) | 1.02 (0.89, 1.17) | 1.09 (0.95, 1.24) | 1.11 (0.97, 1.27) | 0.09 | |
| Multivariable-adjusted HR | 1.00 (referent) | 1.01 (0.88, 1.16) | 0.98 (0.86, 1.13) | 1.03 (0.90, 1.18) | 1.03 (0.90, 1.18) | 0.56 | |
| HPFS | Cases, n | 352 | 337 | 410 | 389 | 356 | |
| Age-adjusted HR | 1.00 (referent) | 0.91 (0.78, 1.05) | 1.07 (0.93, 1.24) | 1.01 (0.87, 1.17) | 0.91 (0.78, 1.05) | 0.24 | |
| Multivariable-adjusted HR | 1.00 (referent) | 0.87 (0.75, 1.01) | 1.01 (0.88, 1.17) | 0.96 (0.83, 1.11) | 0.89 (0.77, 1.03) | 0.24 | |
| Pooled2 | Multivariable-adjusted HR | 1.00 (referent) | 0.94 (0.85, 1.05) | 1.00 (0.90, 1.10) | 1.00 (0.91, 1.10) | 0.97 (0.87, 1.07) | 0.76 |
| 6',7'-Dihydroxybergamottin | |||||||
| NHS | Cases, n | 368 | 426 | 449 | 457 | 522 | |
| Age-adjusted HR | 1.00 (referent) | 1.14 (0.99, 1.31) | 1.17 (1.02, 1.35) | 1.16 (1.01, 1.33) | 1.26 (1.10, 1.44) | 0.006 | |
| Multivariable-adjusted HR | 1.00 (referent) | 1.09 (0.95, 1.26) | 1.11 (0.96, 1.27) | 1.08 (0.94, 1.24) | 1.16 (1.01, 1.33) | 0.081 | |
| HPFS | Cases, n | 287 | 390 | 370 | 401 | 396 | |
| Age-adjusted HR | 1.00 (referent) | 1.33 (1.14, 1.55) | 1.25 (1.07, 1.46) | 1.31 (1.12, 1.52) | 1.20 (1.03, 1.40) | 0.56 | |
| Multivariable-adjusted HR | 1.00 (referent) | 1.18 (1.02, 1.38) | 1.14 (0.97, 1.33) | 1.19 (1.03, 1.39) | 1.13 (0.97, 1.32) | 0.53 | |
| Pooled2 | Multivariable-adjusted HR | 1.00 (referent) | 1.13 (1.02, 1.26) | 1.12 (1.01, 1.24) | 1.13 (1.02, 1.25) | 1.15 (1.04, 1.27) | 0.12 |
| Bergamottin | |||||||
| NHS | Cases, n | 360 | 441 | 455 | 430 | 536 | |
| Age-adjusted HR | 1.00 (referent) | 1.16 (1.01, 1.34) | 1.19 (1.04, 1.37) | 1.09 (0.95, 1.26) | 1.31 (1.14, 1.50) | 0.001 | |
| Multivariable-adjusted HR | 1.00 (referent) | 1.11 (0.96, 1.28) | 1.13 (0.98, 1.29) | 1.02 (0.89, 1.17) | 1.20 (1.05, 1.38) | 0.03 | |
| HPFS | Cases, n | 290 | 385 | 372 | 407 | 390 | |
| Age-adjusted HR | 1.00 (referent) | 1.33 (1.14, 1.55) | 1.25 (1.07, 1.46) | 1.32 (1.14, 1.54) | 1.19 (1.02, 1.39) | 0.59 | |
| Multivariable-adjusted HR | 1.00 (referent) | 1.18 (1.01, 1.38) | 1.14 (0.97, 1.33) | 1.20 (1.03, 1.40) | 1.13 (0.97, 1.32) | 0.49 | |
| Pooled2 | Multivariable-adjusted HR | 1.00 (referent) | 1.14 (1.03, 1.26) | 1.13 (1.02, 1.25) | 1.10 (0.94, 1.30) | 1.17 (1.06, 1.29) | 0.12 |
Multivariable analyses were further adjusted for number of lifetime blistering sunburns (none, 1–2, 3–5, or ≥6), number of arm moles (0, 1–2, 3–5, or ≥6), natural hair color (red, blonde, light brown, or dark brown or black), sunburn susceptibility as child or adolescent (none or some redness, burn, or painful burn or blisters), family history of melanoma (yes or no), alcohol intake (0, 0.1–4.9, 5.0–9.9, 10.0–19.9, or ≥20.0 g/d), UV exposure at residence (quintiles), physical activity (quintiles), routine physical examination (yes or no), intake of total energy (quintiles), and history of basal cell carcinoma and melanoma. HPFS, Health Professionals Follow-Up Study; NHS, Nurses’ Health Study.
Pooled multivariate analysis was defined as combining the data of the 2 cohorts (NHS and HPFS) using a fixed-effects model.