Table 5.
Association of post-diagnosis bisphosphonate use with risk of any breast cancer event (locoregional recurrence, distant recurrence or second primary breast cancer) stratified by ER status.
| ER-negative | ER-positive | |||||||
|---|---|---|---|---|---|---|---|---|
| Person-years at risk | Any Event | Rate per 1000 p-y | HR (95% CI) 1 | Person-years at risk | Any Event | Rate per 1000 p-y | HR (95% CI) 1 | |
| Bisphosphonate Use | ||||||||
| Never BP use2 | 1599 | 82 | 51.3 | 1.00 (ref) | 11805 | 353 | 29.9 | 1.00 (ref) |
| Ever BP use | 250 | 4 | 16.0 | 0.46 (0.16–1.27) | 1684 | 36 | 21.4 | 0.64 (0.45–0.90) |
| Duration of bisphosphonate use | ||||||||
| Never BP use2 | 1599 | 82 | 51.3 | 1.00 (ref) | 11805 | 353 | 29.9 | 1.00 (ref) |
| >1 month to < 1 year | 45 | 1 | 22.2 | 0.41 (0.06–2.94) | 398 | 11 | 27.6 | 0.86 (0.47–1.57) |
| 1 or more years | 205 | 3 | 14.6 | 0.48 (0.15–1.55) | 1286 | 25 | 19.4 | 0.57 (0.38–0.86) |
| Current bisphosphonate use | ||||||||
| Never BP use2 | 1599 | 82 | 51.3 | 1.00 (ref) | 11805 | 353 | 29.9 | 1.00 (ref) |
| Former | 100 | 2 | 20.0 | 0.82 (0.19–3.59) | 733 | 20 | 27.3 | 0.74 (0.46–1.19) |
| Current (within 6 months) | 150 | 2 | 13.3 | 0.33 (0.08–1.34) | 951 | 16 | 16.8 | 0.55 (0.33–0.90) |
| HR for each continuous year of use | 0.73 (0.46–1.15) | 0.86 (0.77–0.97) | ||||||
1
Adjusted for age and source study (the original three studies through which women were ascertained); Hazard Ratio (HR), Confidence Interval (CI)
2
Never use defined as no report of use or one reported instance of use (one month); Ever use defined as greater than one reported instance of use