Table I.
Statistics for characteristics and known risk factors for breast cancer of enrolled Alaska Native women (n=170), 1999–2002
| Totala | Case | Control | pa | |
|---|---|---|---|---|
| Number of women | 170 | 75 | 95 | – |
| Mean age at enrolment in years (range) | 51 (30–88) | 53 (30–78) | 50 (30–88) | 0.08 |
| Mean age at menarche in years (range) | 13 (9–19) | 13 (9–19) | 13 (10–17) | 0.68 |
| Result n (%) | ||||
| Ethnicity | ||||
| Eskimo | 93 (54.7) | 36 (48.0) | 57 (60.0) | 0.06 |
| Indian | 37 (21.8) | 22 (29.3) | 15 (15.8) | |
| Aleut | 27 (15.9) | 9 (12.0) | 18 (19.0) | |
| Other | 13 (7.6) | 8 (10.7) | 5 (5.3) | |
| Service units by region at birth | ||||
| South central (Anchorage) | 33 (19.6) | 15 (20.3) | 18 (19.1) | 0.08 |
| Interior (Fairbanks) | 8 (4.8) | 3 (4.1) | 5 (5.3) | |
| Northwest (Barrow, Kotzebue, Nome) | 46 (27.4) | 17 (23.0) | 29 (30.9) | |
| Southwest (Bethel & Dillingham) | 44 (26.2) | 16 (21.6) | 28 (29.8) | |
| Southeast (Sitka–Mt. Edgecumbe; Annette Isl) | 17 (10.1) | 13 (17.6) | 4 (4.3) | |
| Other | 20 (12.0) | 10 (13.5) | 10 (10.6) | |
| Service units by region at time of enrolment | ||||
| South central (Anchorage) | 99 (58.2) | 42 (56.0) | 57 (60.0) | NA |
| Interior (Fairbanks) | 2 (1.2) | 1 (1.3) | 1 (1.0) | |
| Northwest (Barrow, Kotzebue, Nome) | 32 (18.8) | 14 (18.7) | 18 (19.0) | |
| Southwest (Bethel & Dillingham) | 26 (15.3) | 7 (9.3) | 19 (20.0) | |
| Southeast (Sitka–Mt. Edgecumbe; Annette Isl) | 10 (5.9) | 10 (13.3) | 0 | |
| Other | 1 (0.6) | 1 (1.3) | 0 | |
| Highest education level completed | ||||
| ≤8th grade | 27 (15.9) | 11 (14.7) | 16 (16.8) | 0.45 |
| 9th–11th | 18 (10.6) | 5 (6.7) | 13 (13.7) | |
| High school graduate | 109 (64.1) | 52 (69.3) | 57 (60.0) | |
| ≥College graduate | 16 (9.4) | 7 (9.3) | 9 (9.5) | |
| Smoking (yes) | ||||
| Ever | 132 (77.7) | 62 (82.7) | 70 (73.7) | 0.20 |
| Current (n=135) | 80 (59.3) | 33 (51.6) | 47 (66.2) | 0.11 |
| Alcohol (yes) | ||||
| Ever | 153 (90.0) | 71 (94.7) | 82 (86.3) | 0.08 |
| Current (n=154) | 79 (51.3) | 34 (47.9) | 45 (54.2) | 0.52 |
| Family history of breast cancer (yes) | ||||
| Mother | 7 (4.1) | 3 (4.0) | 4 (4.2) | 0.58 |
| Maternal grandmother | 7 (4.1) | 4 (5.3) | 3 (3.2) | 0.29 |
| Paternal grandmother | 4 (2.4) | 2 (2.7) | 2 (2.1) | 0.91 |
| Sister | 10 (5.9) | 3 (5.0) | 7 (9.1) | 0.51 |
| Daughters | 2 (1.2) | 0 | 2 (2.9) | 0.50 |
| Pregnancies (yes) | ||||
| Ever (n=169) | 158 (93.5) | 71 (96.0) | 87 (91.6) | 0.35 |
| Live births | ||||
| Median # births (range) | 3 (0–11) | 3 (0–10) | 3 (0–11) | 0.77 |
| Number of women (%) | 157 (92.4) | 71 (96.0) | 86 (90.5) | 0.23 |
| Breast fed | ||||
| Median cumulative months (range) | 4 (0–216) | 2 (0–88) | 8 (0–216) | 0.05 |
| Number of women (%) | 106 (62.4) | 45 (60.0) | 61 (64.2) | 0.63 |
| Hormone history (yes) | ||||
| Ever birth control pills | 111 (66.9) | 49 (65.3) | 62 (68.1) | 0.74 |
| Ever hormones | 62 (36.9) | 25 (33.8) | 37 (39.4) | 0.52 |
| Menopausal status (yes) | ||||
| # Women not expecting more periods/who are menopausal (%) | 87 (53.7) | 46 (63.9) | 41 (45.6) | 0.03 |
a
Due to missing responses, sums do not always equal to 170. Where this was the case, percentages were calculated using the number of women answering the question.
b
P-values represent comparison between cases and controls, using t-tests for means of continuous variables, Wilcoxon 2-sample test for medians of continuous variables, and Chi-square tests for categorical variables.