Table 2. Incidence rate and hazard ratios (HRs) for the association between methotrexate, thiopurines, and anti-TNF use and risk of breast cancer recurrence.
| Methotrexate | Thiopurines a | Anti-TNF | ||||
|---|---|---|---|---|---|---|
| User | Nonuser | User | Nonuser | User | Nonuser | |
| Cases of Recurrent breast cancer | 52 | 28 | <11 | <11 | 17 | 48 |
| Person-years of Follow-up | 2,557 | 1,425 | -- | -- | 764 | 2,466 |
| Crude incidence of Breast cancer recurrence (per 1000-py) | 20.3 (15.2-26.7) | 19.6 (13.1-28.4) | 32.3 (8.8-82.6) | 17.6 (7.6-34.6) | 22.3 (13.0-35.6) | 19.5 (14.4-25.8) |
| Adjusted (HR, 95%) | 1.07b (0.67-1.69) | Reference | 2.10c (0.62-7.14) | Reference | 1.13b (0.65-1.97) | Reference |
Person-years for thiopurine exposure are not shown to avoid calculation of absolute number of cases.
No covariates modified the HR by > 10%; covariates assessed included: age, race, calendar year, time from breast cancer surgery to start of follow-up, post surgery hormonal or HER2 therapy, use of non-steroid anti-inflammatory medications in the prior 90 days, prior or concurrent use of immunosuppressive therapy (methotrexate, thiopurines, anti-TNF, or other biologic therapy [abatacept, rituximab, tocilizumab], and histories of chronic kidney disease, chronic liver disease, diabetes mellitus, coronary artery disease, and congestive heart failure.
Adjusted for histories of coronary artery disease and congestive heart failure; no other covariates modified the HR by >10%