Table 3.
Risk factor model results
| Sample size, age | Data collection | Model used | Factors included | Results | |
|---|---|---|---|---|---|
| Brandenburg
[15] (USA) |
550 lesbian, 279 heterosexual (numbers reported don’t quite add up) (mean age 43 (SD 11)) |
Cross-sectional survey (possibly higher risk group) |
Gail |
Gail - Age, age at menarche, age at first live birth, nulliparity, previous breast biopsy, biopsy with a typical hyperplasia, first degree relative with breast cancer |
5-year risk higher in lesbians (mean 0.96% lesbians, 0.85% heterosexual women, p = 0.04) |
| Lifetime (to age 90) risk higher in lesbians (mean 11.6% lesbians, 10.7% heterosexual women, p = 0.001) | |||||
| Bryn Austin
[24] (USA) |
665 lesbian, 309 bisexual, 86,418 heterosexual (age range 25–42 at baseline) |
Prospective population cohort study (premenopausal, normal risk group) |
Rosner-Colditz |
Age, age at menarche, duration of premenopause, age at first birth, number of births, mean BMI during premenopause, height at baseline, mean alcohol intake during premenopause, history of benign breast disease, family history of breast cancer |
Incidence rate ratio lesbian: heterosexual 1.06 (95% CI 1.06-1.06) |
| Incidence rate ratio bisexual: heterosexual 1.10 (95% CI 1.10-1.10). One year incidence rates per 100,000 person-years were 131.6 lesbian, 131.7 bisexual and 122.6 heterosexual | |||||
| Dibble
[23] (USA) |
324 lesbians (mean age 49.7) 324 heterosexual sisters (mean age 48.9) |
Cross-sectional survey (high risk group) |
Modified Gail model |
Menarche age, menopause age, contraceptive pill use, parity, HRT, breastfeeding, hysterectomy, BMI, waist/hip ratio, exercise, smoking, alcohol use, low-fat diet, radiotherapy treatment |
5-year risk higher in lesbians (mean 1.21% lesbians, 1.07% heterosexual women, p < 0.001) |
| Lifetime risk higher in lesbians (mean 11.1% lesbians, 10.4% heterosexual women, p = 0.001) | |||||
| McTiernan et al.
[25] (USA) |
65 lesbians (mean age 40.8 (SD 8.7)) 317 general sample (mean age 42.2 (SD 11.0)) |
From RCTs of breast cancer risk counselling methods (high risk group) |
Gail and Claus |
Gail - Age, age at menarche, age at first live birth, nulliparity, number of previous breast biopsies, biopsy with atypical hyperplasia, first degree relative with breast cancer |
Current age to 79 (lifetime) risk |
| Gail - lesbians 13.2 (SD 5.0), general sample 14.2 (SD 4.3) | |||||
| Claus lesbians 10.9 (SD 4.9), general sample 11.8 (SD 5.1) |
|||||
| Claus – age, relative with breast cancer and their age of onset |