Table 1.
Baseline characteristics of breast cancer survivors in a 2 × 2 factorial randomized controlled trial of metformin and weight loss (n = 333)*
| Characteristic | Metformin and weight loss | Weight loss only | Metformin only | Control | Full sample |
|---|---|---|---|---|---|
| No. | 83 | 83 | 84 | 83 | 333 |
| Age, mean (SD), y | 62.1 (7.1) | 62.9 (6.8) | 62.1 (6.3) | 63.1 (7.4) | 62.6 (6.9) |
| Education, No. (%) | |||||
| Graduate school | 28 (33.7) | 26 (31.3) | 28 (33.3) | 22 (26.5) | 104 (31.2) |
| College graduate | 20 (24.1) | 10 (12.0) | 16 (19.0) | 21 (25.3) | 67 (20.1) |
| Some college | 29 (34.9) | 36 (43.4) | 37 (44.0) | 30 (36.1) | 132 (39.6) |
| High school or less | 6 (7.2) | 11 (13.3) | 3 (3.6) | 10 (12.0) | 30 (9.0) |
| Time since diagnosis (SD), y | 2.4 (1.9) | 3.1 (2.4) | 2.6 (1.9) | 2.5 (1.7) | 2.7 (2.0) |
| Body mass index (SD), kg/m2 | 31.4 (5.2) | 30.8 (4.6) | 30.8 (4.7) | 31.5 (5.4) | 31.1 (5.0) |
| Waist circumference (SD), cm | 99.2 (12.6) | 97.6 (11.4) | 98.6 (11.4) | 99.3 (12.6) | 98.7 (12.0) |
| Race, No. (%) | |||||
| White | 69 (83.1) | 68 (81.9) | 70 (83.3) | 70 (84.3) | 278 (83.5) |
| Black or African American | 3 (3.6) | 2 (2.4) | 5 (6.0) | 2 (2.4) | 12 (3.6) |
| Asian | 3 (3.6) | 0 (0.0) | 1 (1.2) | 2 (2.4) | 6 (1.8) |
| Mixed race or other race | 8 (9.6) | 13 (15.7) | 8 (9.5) | 9 (10.8) | 37 (11.1) |
| Ethnicity, No. (%) | |||||
| Non-Hispanic | 72 (87.8) | 71 (85.5) | 80 (95.2) | 71 (85.5) | 295 (88.6) |
| Hispanic | 10 (12.2) | 12 (14.5) | 4 (4.8) | 12 (14.5) | 38 (11.4) |
| Cancer stage, No. (%) | |||||
| Stage I | 41 (49.4) | 40 (48.2) | 40 (47.6) | 40 (48.2) | 161 (48.4) |
| Stage II | 30 (36.1) | 31 (37.3) | 28 (33.3) | 27 (32.5) | 116 (34.8) |
| Stage III | 12 (14.5) | 12 (14.5) | 16 (19.0) | 16 (19.3) | 56 (16.8) |
| Receptor status, No. (%) | |||||
| ER+ or PR+ HER2- | 52 (62.7) | 63 (75.9) | 62 (73.8) | 63 (75.9) | 240 (72.1) |
| HER2+ | 15 (18.1) | 11 (13.3) | 11 (13.1) | 14 (16.9) | 51 (15.3) |
| Triple-negative (ER-, PR-, HER2-) | 10 (12.0) | 5 (6.0) | 10 (11.9) | 5 (6.0) | 30 (9.0) |
| Missing data | 6 (7.2) | 4 (4.8) | 1 (1.2) | 1 (1.2) | 12 (3.6) |
| Any current alcohol intake, No. (%) | |||||
| Yes | 66 (79.5) | 68 (81.9) | 66 (78.6) | 66 (79.5) | 225 (67.6) |
*
There were no statistically significant differences across the study arms. ER = estrogen receptor; HER2 = human epidermal growth factor receptor 2; PR = progesterone receptor.