Table 1.
Characteristics of study participants (n = 100,436) a by categories of skincare product use
| Characteristics | Non-users | Light users | Moderate users | Frequent users | Heavy users |
|---|---|---|---|---|---|
| n | 1840 | 36,598 | 25,718 | 34,203 | 2077 |
| % skin creamed per day | 0–0.001 | 0.002- < 35.0 | 35.0- < 65.0 | 65.0- < 115.0 | 115.0–200 |
| Incident cases of breast cancer (n) | 65 | 1176 | 801 | 1088 | 58 |
| Breast cancer subtype, % b | |||||
| ER+ | 83.1 | 83.8 | 85.3 | 84.1 | 84.5 |
| ER- | 15.4 | 13.9 | 12.1 | 12.9 | 15.5 |
| Incident cases of endometrial cancer (n) | 15 | 261 | 141 | 216 | 9 |
| Age at enrollment (years), mean ± SD | 54.8 ± 5.0 | 54.3 ± 4.8 | 54.9 ± 4.8 | 54.8 ± 4.8 | 54.8 ± 4.8 |
| Education (years), % | |||||
| < 10 | 27.2 | 15.9 | 17.0 | 15.4 | 15.1 |
| 10–12 | 30.4 | 32.1 | 36.4 | 36.1 | 34.8 |
| > 12 | 42.4 | 51.9 | 46.5 | 48.5 | 50.1 |
| BMI, % | |||||
| Under−/Normal weight | 36.6 | 50.7 | 56.7 | 60.5 | 66.4 |
| Overweight | 33.4 | 34.8 | 32.7 | 30.7 | 25.7 |
| Obese | 30.0 | 14.5 | 10.6 | 8.8 | 7.9 |
| Menopausal status at enrollment, % | |||||
| Pre | 14.2 | 15.7 | 13.0 | 13.4 | 13.4 |
| Peri | 9.2 | 10.3 | 9.5 | 9.4 | 8.9 |
| Post | 72.4 | 68.6 | 72.2 | 71.5 | 72.1 |
| Unknown | 4.2 | 5.4 | 5.2 | 5.7 | 5.6 |
| Age at menarche, mean ± SD | 13.2 ± 1.5 | 13.3 ± 1.4 | 13.3 ± 1.4 | 13.2 ± 1.4 | 13.2 ± 1.5 |
| Age at first full term pregnancy, mean ± SD | 23.9 ± 4.6 | 24.4 ± 4.7 | 24.0 ± 4.4 | 24.0 ± 4.4 | 23.9 ± 4.4 |
| Parity, % | |||||
| 0 | 10.3 | 10.2 | 9.3 | 9.2 | 10.4 |
| 1–2 | 47.3 | 53.3 | 56.7 | 59.4 | 58.3 |
| ≥3 | 42.4 | 36.6 | 33.9 | 31.4 | 31.3 |
| OC use, % | |||||
| Never | 48.2 | 40.3 | 38.1 | 36.0 | 36.4 |
| Former | 51.3 | 59.2 | 61.4 | 63.4 | 62.8 |
| Current | 0.5 | 0.5 | 0.5 | 0.6 | 0.8 |
| MHT use, % | |||||
| Never | 69.7 | 63.7 | 56.7 | 53.7 | 50.8 |
| Former | 21.4 | 23.5 | 27.4 | 27.2 | 27.3 |
| Current | 8.9 | 12.8 | 16.0 | 19.0 | 21.8 |
| IUD use, % | |||||
| Ever | 7.7 | 11.6 | 11.9 | 12.2 | 12.7 |
| Smoking, % | |||||
| Never | 37.4 | 36.0 | 32.4 | 31.0 | 31.6 |
| Former | 30.9 | 40.8 | 43.9 | 45.4 | 43.6 |
| Current | 31.7 | 23.2 | 23.7 | 23.6 | 24.8 |
| Physical activity, % | |||||
| Low | 37.6 | 24.8 | 19.8 | 16.5 | 14.6 |
| Moderate | 34.8 | 41.8 | 42.4 | 38.9 | 32.6 |
| High | 27.6 | 33.4 | 37.8 | 44.6 | 52.8 |
| Alcohol intake (g/day), mean ± SD | 2.7 ± 4.2 | 3.7 ± 4.3) | 4.1 ± 4.2 | 4.4 ± 4.3 | 4.2 ± 4.4 |
SD standard deviation, ER estrogen receptor, BMI body mass index, OC oral contraceptive, MHT menopausal hormone therapy, IUD intrauterine device
a6542 participants had missing values on skincare product use
bPercentage of ER+/ER- subtypes does not add up to 100 due to missing values on hormone receptor status