| No. of breast cancers | Principle testosterone type/route | Duration of usage (yr) | Risk (CI) | Refs. | |
|---|---|---|---|---|---|
| E+T | No MHT | ||||
| 7 | 2,883f | Testosterone (sc) | Mean, 5.8 | 115/100,000 E+Ta, 293/100,000 E+P+T | 169 |
| 29, 3 (T only) | 1,647 | Methyltestosterone (O) | Up to 24 | RR 1.77 (1.22–2.56)b, E+T; RR 2.52 (0.80–7.94), T only | 165 |
| 35 | 558 | Methyltestosterone (O) | Mean, 4.6 | RR 1.42 (0.95–2.11)c | 167 |
| 12 | 1,333 | Testosterone (sc or TD) | Median, 1.3 | 299/100,000 E+T+Pa, RR 1.35 (0.76–2.38) | 170 |
c
Adjusted for BMI, age at menopause, history of breast cancer in a first-degree relative, number of mammograms in the 5 yr before study enrollment, and prior hormone therapy use.
d
No MHT group taken from MWS.
e
No MHT group taken from State of Victoria, Australia population data.
f
Number estimated from MWS by multiplying person-years times duration of follow-up (2.6 yr).