Table 2.
Survival analyses of relapse and mortality according to fractionation schedule in START Trial A
| Events/total (%) | Estimated % with event by 5 years (95% CI) | Crude hazard ratio (95% CI) | Wald test p value* | |
|---|---|---|---|---|
| Local relapse† | ||||
| 50 Gy | 25/749 (3·3) | 3·2 (1·9–4·6) | 1 | − |
| 41·6 Gy | 28/750 (3·7) | 3·2 (1·9–4·5) | 1·09 (0·64–1·88) | 0·74 |
| 39 Gy | 31/737 (4·2) | 4·6 (3·0–6·2) | 1·25 (0·74–2·12) | 0·40 |
| Local-regional relapse | ||||
| 50 Gy | 28/749 (3·7) | 3·6 (2·2–5·1) | 1 | − |
| 41·6 Gy | 30/750 (4·0) | 3·5 (2·1–4·3) | 1·05 (0·63–1·75) | 0·86 |
| 39 Gy | 35/737 (4·7) | 5·2 (3·5–6·9) | 1·26 (0·77–2·08) | 0·35 |
| Distant relapse | ||||
| 50 Gy | 73/749 (9·7) | 9·8 (7·5–12·0) | 1 | − |
| 41·6 Gy | 69/750 (9·2) | 9·5 (7·3–11·7) | 0·92 (0·66–1·28) | 0·64 |
| 39 Gy | 93/737 (12·6) | 11·9 (9·5–14·4) | 1·29 (0·95–1·76) | 0·10 |
| Any breast cancer-related event‡ | ||||
| 50 Gy | 102/749 (13·6) | 13·6 (11·0–16·2) | 1 | − |
| 41·6 Gy | 91/750 (12·1) | 12·0 (9·6–14·5) | 0·87 (0·65–1·15) | 0·33 |
| 39 Gy | 115/737 (15·6) | 15·2 (12·5–17·9) | 1·14 (0·87–1·49) | 0·33 |
| All-cause mortality | ||||
| 50 Gy | 84/749 (11·2) | 11·1 (8·7–13·4) | 1 | − |
| 41·6 Gy | 89/750 (11·9) | 11·3 (8·9–13·7) | 1·04 (0·77–1·40) | 0·81 |
| 39 Gy | 83/737 (11·3) | 10·7 (8·3–13·1) | 1·00 (0·74–1·36) | 0·99 |
*
p value from Wald test comparing each schedule with 50 Gy.
†
Local relapse defined as ipsilateral local tumour relapse in breast parenchyma/breast skin/chest wall skin.
‡
Breast cancer-related events: local, regional, or distant relapse, breast cancer death, contralateral breast cancer (disease-free survival).