Table 4.
Pooled risk of site-specific squamous cell carcinoma according to frequency of citrus consumption in the HPFS (1986–2010) and NHS (1984–2010)
| Serving category | P for trend | ||||
|---|---|---|---|---|---|
| Overall citrus | <2 per week | 2–4 per week | 5–6 per week | ≥1 per day | |
| No. of person-years | 400456 | 371958 | 465228 | 738297 | |
| Risk of SCC on the body sites with higher continuous sun exposure (head, neck and extremities) | |||||
| No. of cases | 406 | 526 | 722 | 1104 | |
| Multivariable-adjusted HR (95% CI) | 1.00 | 1.15 (1.01–1.32) | 1.17 (1.02–1.33) | 1.23 (1.08–1.39) | 0.004 |
| Risk of SCC on the body sites with lower continuous sun exposure (truncal sites) | |||||
| No. of cases | 78 | 91 | 126 | 188 | |
| Multivariable-adjusted HR (95% CI) | 1.00 | 1.01 (0.74–1.38) | 1.07 (0.63–1.81) | 1.07 (0.76–1.50) | 0.70 |
| Grapefruit | Never | <1 per week | 1 per week | ≥2 per week | |
| No. of person-years | 509252 | 639008 | 349832 | 477847 | |
| Risk of overall SCC on the body sites with higher continuous sun exposure (head, neck and extremities) | |||||
| No. of cases | 471 | 935 | 496 | 856 | |
| Multivariable-adjusted HR (95% CI) | 1.00 | 1.21 (1.08–1.36) | 1.18 (0.94–1.47) | 1.33 (1.15–1.53) | 0.01 |
| Risk of overall SCC on the body sites with lower continuous sun exposure (truncal sites) | |||||
| No. of cases | 93 | 167 | 84 | 139 | |
| Multivariable-adjusted HR (95% CI) | 1.00 | 1.09 (0.83–1.43) | 1.03 (0.75–1.43) | 1.15 (0.84–1.57) | 0.58 |
| Grapefruit juice | Never | <1 per week | 1 per week | ≥2 per week | |
| No. of person-years | 1092966 | 476005 | 165397 | 241572 | |
| Risk of overall SCC on the body sites with higher continuous sun exposure (head, neck and extremities) | |||||
| No. of cases | 1364 | 765 | 236 | 393 | |
| Multivariable-adjusted HR (95% CI) | 1.00 | 0.97 (0.88–1.06) | 0.91 (0.79–1.05) | 1.02 (0.91–1.15) | 0.89 |
| Risk of overall SCC on the body sites with lower continuous sun exposure (truncal sites) | |||||
| No. of cases | 247 | 140 | 45 | 51 | |
| Multivariable-adjusted HR (95% CI) | 1.00 | 0.99 (0.80–1.24) | 0.98 (0.65–1.47) | 0.74 (0.54–1.02) | 0.18 |
| Oranges | Never | <1 per week | 1 per week | ≥2 per week | |
| No. of person-years | 228853 | 518773 | 401333 | 826980 | |
| Risk of overall SCC on the body sites with higher continuous sun exposure (head, neck and extremities) | |||||
| No. of cases | 210 | 699 | 603 | 1246 | |
| Multivariable-adjusted HR (95% CI) | 1.00 | 1.03 (0.88–1.21) | 1.10 (0.93–1.30) | 0.96 (0.81–1.13) | 0.41 |
| Risk of overall SCC on the body sites with lower continuous sun exposure (truncal sites) | |||||
| No. of cases | 43 | 117 | 92 | 231 | |
| Multivariable-adjusted HR (95% CI) | 1.00 | 0.82 (0.57–1.18) | 0.80 (0.54–1.18) | 0.88 (0.60–1.29) | 0.97 |
| Orange juice | <1 per week | 1–2 per week | 3–4 per week | ≥5 per week | |
| No. of person-years | 499507 | 451276 | 395566 | 629591 | |
| Risk of overall SCC on the body sites with higher continuous sun exposure (head, neck and extremities) | |||||
| No. of cases | 542 | 656 | 587 | 973 | |
| Multivariable-adjusted HR (95% CI) | 1.00 | 1.06 (0.93–1.21) | 1.10 (0.96–1.25) | 1.13 (1.01–1.26) | 0.03 |
| Risk of overall SCC on the body sites with lower continuous sun exposure (truncal sites) | |||||
| No. of cases | 102 | 107 | 111 | 163 | |
| Multivariable-adjusted HR (95% CI) | 1.00 | 0.92 (0.70–1.21) | 1.13 (0.75–1.72) | 1.02 (0.64–1.64) | 0.73 |
Multivariable hazard ratios were adjusted for the covariates listed in the Table 2. Results in the HPFS and NHS were pooled using the random-effects model.