TABLE 1.
Baseline characteristics of participants by total vitamin A intake (dietary and supplements) in the Women's Health Initiative.
| Characteristic | Total, N (%) | Total vitamin A intake a | |||
|---|---|---|---|---|---|
| 1st tertile | 2nd tertile | 3rd tertile | p‐value b , c | ||
| [27–88 815 mcg] | [888–5162 mcg] | [5162–80 505 mcg] | |||
| N (%) | N (%) | N (%) | |||
| New diagnosis of melanoma | 1154 (2.2) | 360 (2.0) | 397 (2.3) | 397 (2.3) | |
| Tumour behaviour at diagnosis | 0.93 | ||||
| In situ disease | 545 (47.2) | 172 (1.0) | 183 (1.0) | 190 (1.1) | |
| Invasive disease | 595 (51.6) | 184 (1.0) | 210 (1.2) | 201 (1.1) | |
| Unknown | 14 (1.2) | 4 (0) | 4 (0) | 6 (0) | |
| New diagnosis of keratinocyte cancer (NMSC) | 9832 (18.6) | 3087 (17.5) | 3355 (19.0) | 3390 (19.2) | <0.01 |
| Age | <0.01 | ||||
| 50–59 | 16 989 (32.1) | 6160 (35.0) | 5511 (31.3) | 5318 (30.2) | |
| 60–69 | 23 773 (45.0) | 7749 (44.0) | 7978 (45.3) | 8046 (45.6) | |
| 70+ | 12 115 (22.9) | 3716 (21.1) | 4137 (23.5) | 4262 (24.2) | |
| Education | <0.01 | ||||
| None to some high school | 1430 (2.7) | 628 (3.6) | 446 (2.5) | 356 (2.0) | |
| High school diploma or GED | 8387 (15.9) | 3300 (18.7) | 2720 (15.4) | 2367 (13.4) | |
| Some college, college degree or higher | 43 060 (81.4) | 13 697 (77.7) | 14 460 (82.0) | 14 903 (84.6) | |
| Income | 0.02 | ||||
| <$20 000–$49 999 | 29 369 (55.5) | 9921 (56.3) | 9826 (55.7) | 9622 (54.6) | |
| $50 000–$99 999 | 16 895 (32.0) | 5520 (31.3) | 5597 (31.8) | 5778 (32.8) | |
| ≥$100 000 | 6613 (12.5) | 2184 (12.4) | 2203 (12.5) | 2226 (12.6) | |
| Body mass index (kg/m2) | <0.01 | ||||
| <18.5 (underweight) | 542 (1.0) | 163 (0.9) | 172 (1.0) | 207 (1.2) | |
| 18.5–24.9 (normal weight) | 22 218 (42.0) | 7130 (40.5) | 7343 (41.7) | 7745 (43.9) | |
| ≥25 (overweight or obese) | 30 117 (57.0) | 10 332 (58.6) | 10 111 (57.4) | 9674 (54.9) | |
| Smoking history | <0.01 | ||||
| Never | 26 448 (50.0) | 8657 (49.1) | 9022 (51.2) | 8769 (49.8) | |
| Past | 23 717 (44.9) | 7804 (44.3) | 7781 (44.1) | 8132 (46.1) | |
| Current | 2712 (5.1) | 1164 (6.6) | 823 (4.7) | 725 (4.1) | |
| Prior history of melanoma | 5005 (9.5) | 1475 (8.4) | 1666 (9.5) | 1864 (10.6) | 0.39 |
| Prior history of NMSC | 6084 (11.5) | 1885 (10.7) | 2022 (11.5) | 2177 (12.4) | <0.01 |
| Prior history of non‐skin cancer | 36 252 (68.6) | 12 033 (68.3) | 12 080 (68.5) | 12 139 (68.9) | <0.01 |
| Family history of cancer | 46 594 (88.1) | 15 301 (86.8) | 15 499 (87.9) | 15 794 (89.6) | 0.48 |
| Had last medical visit within 1 year | 5005 (9.5) | 1475 (8.4) | 1666 (9.5) | 1864 (10.6) | <0.01 |
| Regional solar irradiation (in Langleys) | <0.01 | ||||
| 300–325 | 17 115 (32.4) | 5868 (33.3) | 5957 (33.8) | 5290 (30.0) | |
| 350 | 11 021 (20.8) | 3469 (19.7) | 3704 (21.0) | 3848 (21.8) | |
| 375–380 | 5686 (10.8) | 2089 (11.9) | 1825 (10.4) | 1772 (10.1) | |
| 400–430 | 8707 (16.5) | 2899 (16.4) | 2748 (15.6) | 3060 (17.4) | |
| 475–500 | 10 348 (19.6) | 3300 (18.7) | 3392 (19.2) | 3656 (20.7) | |
| Skin reaction to sun | 0.01 | ||||
| Does not burn | 18 878 (35.7) | 6495 (36.9) | 6235 (35.4) | 6131 (34.8) | |
| Burns, then tans | 13 596 (25.7) | 4435 (25.2) | 4550 (25.9) | 4588 (26.1) | |
| Burns, then tans a minimal amount | 14 440 (27.3) | 4664 (26.5) | 4827 (27.4) | 4926 (28.0) | |
| Burns but does not tan | 5963 (11.3) | 2007 (11.4) | 1989 (11.3) | 1956 (11.1) | |
| Average daily sun exposure in summer during childhood | 0.25 | ||||
| <30 min | 1155 (2.2) | 412 (2.3) | 392 (2.2) | 351 (2.0) | |
| 30 min–2 h | 13 703 (25.9) | 4554 (25.8) | 4549 (25.8) | 4600 (26.1) | |
| >2 h | 38 019 (71.9) | 12 659 (71.8) | 12 685 (72) | 12 675 (71.9) | |
| Average daily sun exposure in summer now | <0.01 | ||||
| <30 min | 16 088 (30.4) | 5311 (30.1) | 5341 (30.3) | 5436 (30.8) | |
| 30 min–2 h | 26 618 (50.3) | 8746 (49.6) | 8933 (50.7) | 8939 (50.7) | |
| >2 h | 10 171 (19.2) | 3568 (20.2) | 3352 (19.0) | 3251 (18.4) | |
| Sunscreen SPF | <0.01 | ||||
| None | 24 586 (46.5) | 9029 (51.2) | 8183 (46.4) | 7374 (41.8) | |
| SPF 2–14 | 2609 (4.9) | 894 (5.1) | 878 (5.0) | 837 (4.7) | |
| SPF 15–25 | 16 300 (30.8) | 4935 (28.0) | 5414 (30.7) | 5951 (33.8) | |
| SPF 25+ | 9382 (17.7) | 2767 (15.7) | 3151 (17.9) | 3464 (19.7) | |
Abbreviation: CI, confidence interval; GED, general educational development.
a
Total intake includes intake via diet and supplements. Dietary intake is defined as consumption derived from food. All units are micrograms.
b
Bolded values indicate two‐sided statistical significance at the p < 0.05 level.
c
Chi‐square test was used.