Table I.
Descriptive characteristics of invasive ovarian cancer cases classified by histologic pathways and controls in the NECC study.
| Population characteristics | Controls | G1 serous and all mucinous | Endometrioid and clear cell | G2/3 serous, other/ undifferentiated |
|---|---|---|---|---|
| Participants, N | 2100 | 144 | 441 | 986 |
| Mean (SD) | ||||
| Age (years)a | 52.3 (12.6) | 50.7 (13.4) | 50.5 (11.0) | 56.6 (10.2) |
| Parity among parous women | 2.7 (1.4) | 2.5 (1.3) | 2.2 (1.1) | 2.6 (1.3) |
| Duration of breastfeeding (months)b | 8.6 (14.2) | 7.2 (15.6) | 5.3 (9.7) | 5.6 (11.7) |
| Duration of OC pill use (years)c | 5.7 (5.0) | 4.9 (4.8) | 4.7 (4.6) | 4.3 (4.4) |
| n (%) | ||||
| Family history of ovarian cancer | 54 (2.6) | 5 (3.5) | 17 (3.9) | 55 (5.6) |
| Family history of breast cancer | 279 (13.3) | 20 (13.9) | 62 (14.1) | 174 (17.7) |
| Tumor staged | ||||
| I | — | 94 (65.7) | 287 (65.4) | 118 (12.0) |
| II | — | 13 (9.1) | 62 (14.1) | 101 (10.3) |
| III | — | 35 (24.5) | 86 (19.6) | 713 (72.4) |
| IV | — | 1 (0.7) | 4 (0.9) | 53 (5.4) |
| Tumor grade | ||||
| 1 | — | 104 (72.2) | 101 (22.9) | — |
| 2 | — | 29 (20.1) | 145 (32.9) | 139 (14.1) |
| 3 | — | 7 (4.9) | 143 (32.4) | 805 (81.6) |
| Ungraded | — | 4 (2.8) | 46 (10.4) | 34 (3.5) |
| Missing | — | — | 6 (1.4) | 8 (0.8) |
| Tumor histology | ||||
| Serous invasive | — | 49 (34.0) | — | 846 (85.8) |
| Mucinous | — | 95 (66.0) | — | — |
| Endometrioid/mixed | — | — | 327 (74.2) | — |
| Clear cell | — | — | 114 (25.9) | — |
| Other/undifferentiated | — | — | — | 140 (14.2) |
aCases and controls were frequency-matched on age.
bTotal duration of breastfeeding among parous women.
cDuration of OC use among ever users (used OCs for ≥3 months).
dNumbers may not add up to total due to missing data.