Table 1. Characteristics of endometrial cancer cases and population-based controls*.
| Characteristic (N missing) | Number (Percent) | Cases (N = 631) | Controls (N = 879) | p-value** |
|---|---|---|---|---|
| Demographics | ||||
| Age at diagnosis | < .0001 | |||
| <40 | 32 (2.1) | 20 (3.2) | 12 (1.4) | |
| 40–44 | 38 (2.5) | 24 (3.8) | 14 (1.6) | |
| 45–49 | 54 (3.6) | 30 (4.8) | 24 (2.7) | |
| 50–54 | 144 (9.5) | 82 (13.0) | 62 (7.0) | |
| 55+ | 1242 (82.2) | 475 (75.3) | 767 (87.3) | |
| Mean (SD) | 61.7 (9.1) | 60.1 (9.5) | 62.9 (8.6) | < .0001 |
| Education | ||||
| High school or less | 607 (40.2) | 231 (36.6) | 376 (42.8) | .046 |
| 1–3 years of college | 414 (27.4) | 179 (28.4) | 235 (26.7) | |
| College or more | 489 (32.4) | 221 (35.0) | 268 (30.5) | |
| Employment | .22 | |||
| Not in labor force | 722 (47.8) | 290 (46.0) | 432 (49.2) | |
| Working | 788 (52.2) | 341 (54.0) | 447 (50.8) | |
| Family income, annual (101) | .09 | |||
| ≤ $30,000 | 417 (29.6) | 188 (31.3) | 229 (28.3) | |
| $30,001–$50,000 | 389 (27.6) | 177 (29.4) | 212 (26.2) | |
| $50,001–$100,000 | 424 (30.1) | 160 (26.6) | 264 (32.7) | |
| >$100,000 | 179 (12.7) | 76 (12.6) | 103 (12.8) | |
| Marital status | < .0001 | |||
| Married/living with partner | 1078 (71.4) | 417 (66.1) | 661 (75.2) | |
| Divorced, separated, widowed | 342 (22.6) | 153 (24.2) | 189 (21.5) | |
| Never married | 90 (6.0) | 61 (9.7) | 29 (3.3) | |
| Race/ethnicity (6) | ||||
| Hispanic | 11 (0.7) | 5 (0.8) | 6 (0.7) | .79 |
| Non-Hispanic Black | 37 (2.5) | 26 (4.1) | 11 (1.3) | .0004 |
| Non-Hispanic White | 1437 (95.6) | 595 (94.6) | 842 (96.2) | |
| Other Non-Hispanic | 19 (1.3) | 3 (0.5) | 16 (1.8) | .024 |
| Work schedule (723) | .32 | |||
| Regular daytime shift | 650 (82.6) | 286 (84.1) | 364 (81.4) | |
| Other shift | 137 (17.4) | 54 (15.9) | 83 (18.6) | |
| Dietary habits | ||||
| Drink alcoholic beverages, days/week (18) | ||||
| 0 | 706 (47.3) | 290 (46.5) | 416 (47.9) | .07 |
| <1 | 405 (27.1) | 190 (30.4) | 215 (24.8) | |
| 1–2.9 | 183 (12.3) | 70 (11.2) | 113 (13.0) | |
| 3 or more | 198 (13.3) | 74 (11.9) | 124 (14.3) | |
| Protein shake consumption (5) | .02 | |||
| None | 1328 (88.2) | 542 (86.0) | 786 (89.8) | |
| Less than 2 per week | 73 (4.8) | 31 (4.9) | 42 (4.8) | |
| 2 per week or more | 104 (6.9) | 57 (9.0) | 47 (5.4) | |
| Whole milk consumption | .038 | |||
| 5 or more times per week | 75 (5.0) | 40 (6.3) | 35 (4.0) | |
| Less than 5 times per week | 1435 (95.0) | 591 (94.7) | 844 (96.0) | |
| Physical activity and weight | ||||
| Body mass index, year before diagnosis (20) | ||||
| Mean (SD) | 32.0 (8.9) | 35.7 (9.9) | 29.3 (7.0) | < .0001 |
| MET-hours/week, total (8) | ||||
| Mean (SD) | 38.2 (58.9) | 32.5 (51.5) | 42.3 (63.4) | .001 |
| Weight gain since age 25 (23) | ||||
| Mean (SD) | 20.5 (18.3) | 25.0 (20.4) | 17.2 (15.9) | < .0001 |
| Smoking history | ||||
| Smoke cigarettes (3) | .003 | |||
| Never | 946 (62.8) | 413 (65.7) | 533 (60.7) | |
| Former | 418 (27.7) | 175 (27.8) | 243 (27.7) | |
| Current | 143 (9.5) | 41 (6.5) | 102 (11.6) | |
| Smoking, total pack-years (6) | ||||
| Mean for ever-smokers (SD) | 9.0 (18.8) | 7.6 (13.5) | 10.9 (16.7) | .0002 |
| Medical history | ||||
| Breast cancer (3) | .0002 | |||
| Yes | 75 (5.0) | 16 (2.5) | 59 (6.7) | |
| No | 1432 (95.0) | 614 (97.5) | 818 (93.3) | |
| Diabetes (4) | ||||
| Yes | 291 (19.3) | 155 (24.7) | 136 (15.5) | < .0001 |
| No | 1215 (80.7) | 476 (75.3) | 742 (84.5) | |
| Endometrial cancer in first degree relative (67) | .0001 | |||
| Yes | 48 (3.3) | 33 (5.5) | 15 (1.8) | |
| No | 1395 (96.7) | 570 (94.5) | 825 (98.2) | |
| Endometriosis (31) | .07 | |||
| Yes | 250 (16.9) | 116 (19.0) | 134 (15.4) | |
| No | 1229 (83.1) | 494 (81.0) | 735 (84.6) | |
| Hypertension (8) | .008 | |||
| Yes | 799 (53.2) | 359 (57.3) | 440 (50.3) | |
| No | 703 (46.8) | 268 (42.7) | 435 (49.7) | |
| Ovarian cancer (10) | < .0001 | |||
| Yes | 46 (3.1) | 35 (5.6) | 11 (1.3) | |
| No | 1454 (96.9) | 590 (94.4) | 864 (98.7) | |
| Medications and treatments | ||||
| Birth control, years used (7)*** | ||||
| Mean (SD) | 5.8 (7.2) | 4.8 (6.0) | 6.5 (7.9) | < .0001 |
| Hormone replacement therapy, years used (22) | ||||
| Mean (SD) | 3.2 (7.1) | 2.0 (5.6) | 4.1 (7.9) | < .0001 |
| Reproductive history | ||||
| Age of menarche 11 or earlier | .004 | |||
| Yes | 330 (21.8) | 161 (25.5) | 169 (19.2) | |
| No | 1180 (78.2) | 470 (74.5) | 710 (80.8) | |
| Menopause status, year before diagnosis (6) | < .0001 | |||
| Premenopausal | 220 (14.6) | 149 (23.6) | 71 (8.1) | |
| Postmenopausal | 1284 (85.0) | 481 (76.2) | 803 (91.4) |
*9 controls who reported a diagnosis of endometrial cancer were excluded. Variables refer to the year prior to diagnosis of endometrial cancer unless otherwise specified.
**P-value for chi-square analysis except for means, which were compared with a t-test. Fisher’s Exact test was used for race/ethnicity where there were low numbers of participants in one category.
***Birth control refers to methods that release hormones, such as birth control pills, injections, patches, progestogen implants (Norplant), progestin-releasing intrauterine devices, or vaginal rings.