Table 1.
Selected participant characteristics of a case-cohort analysis of PGE-M and EMs in the Sister Study
| Cases (N=295) | Subcohort (N=294) | p-value1 | |
|---|---|---|---|
| No (%) | |||
| Non-Hispanic white | 268 (90.9%) | 275 (93.5%) | 0.224 |
| Current smokers | 29 (9.8%) | 15 (5.1%) | 0.048 |
| Regular current drinkers | 212 (71.9%) | 204 (69.4%) | 0.536 |
| Regular NSAID users2 | 181 (61.4%) | 154 (52.4%) | 0.028 |
| Median (25th–75th percentile) | |||
| Age, y | 61 (57–65) | 61 (56–65) | 0.519 |
| Age at menarche, y | 13 (12–13) | 13 (12–14) | 0.006 |
| Age at menopause, y | 50 (45–53) | 50 (45–53) | 0.896 |
| Number of parity | 2 (1–3) | 2 (1–3) | 0.594 |
| Years of HRT use in the past | 1 (0–9) | 2 (0–9) | 0.619 |
| Number of first degree relatives with breast cancer | 1 (1–2) | 1 (1–2) | 0.007 |
| BMI, kg/m2 | 27.3 (24–32) | 26.7 (23–31) | 0.290 |
| Urinary PGE-M, ng/mg Cr. | 5.6 (3.8–8.5) | 5.3 (3.4–8.2) | 0.419 |
| Urinary levels of estrogens and estrogen metabolites (EMs), pg/mg Cr. | |||
| Total estrogens and EMs | 12,704 (7462–21302) | 12,112 (7826–17926) | 0.580 |
| Parent estrogens | 1,536 (869–2522) | 1,324 (829–2168) | 0.044 |
| Estrone | 1,205 (671–1,917) | 1,053 (644–1699) | 0.057 |
| Estradiol | 313 (172–548) | 276 (162–478) | 0.057 |
| C2-hydroxylation pathway | 1647 (885–2964) | 1509 (911–2785) | 0.049 |
| 2-hydroxyestrone | 1,026 (588–2000) | 935 (499–1602) | 0.063 |
| 2-hydroxyestradiol | 174 (71–392) | 177 (69–447) | 0.361 |
| 2-methoxyestrone | 146 (49–301) | 134 (41–282) | 0.757 |
| 2-methoxyestradiol | 19 (0.35–67) | 18 (0.55–75) | 0.610 |
| 3-methoxyestrone | 39 (16–96) | 38 (12–79) | 0.406 |
| C4-hydroxylation pathway | 492 (266–1041) | 562 (263–1126) | 0.603 |
| 4-hydroxyestrone | 400 (192–869) | 454 (207–916) | 0.387 |
| 4-methoxyestrone | 7.1 (0.02–47.7) | 10.3 (0.01–58.4) | 0.541 |
| 4-methoxyestradiol | 6.2 (0.02–25.9) | 5.7 (0.02–34.2) | 0.912 |
| C16-hydroxylation pathway | 7596 (3739–13768) | 7436 (4064–12372) | 0.866 |
| 16α-hydroxyestrone | 377 (163–742) | 345 (145–721) | 0.503 |
| Estriol | 5536 (2508–11390) | 5847 (2465–10784) | 0.807 |
| 16-epiestriol | 215 (112–436) | 196 (97–374) | 0.154 |
| 17-epiestriol | 37 (8–125) | 32 (6–113) | 0.293 |
| 16-ketoestradiol | 398 (184–788) | 415 (198–771) | 0.958 |
| C2-hydroxylation pathway EMs: C16α-hydroxylation pathway EMs | 0.30 (0.15–0.68) | 0.27 (0.73–0.71) | 0.428 |
1
Chi square test for categorical variables and Wilcoxon rank-sum test for continuous variables;
2
regular use of NSAIDs defined as ≥ 0.75 pill-years of NSAID use (equivalent to at least 3 pills of NSAID use per week for 3 months or longer).