Table 2.
Risk estimations for radiation-induced mortality.
| WBI + LNI + MI | Photon | Proton | Ph/Pr DIBH | Ph/Pr SB | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| DIBH | SB | p-value DIBH-SB | DIBH | SB | p-value DIBH-SB | p-value | p-value | |||||
| Mean | Range | Mean | Range | Mean | Range | Mean | Range | |||||
| Heart_mean dose | 2.54 | (1.43–4.15) | 4.55 | (2.40–6.58) | < 0.001 | 0.78 | (0.1–2.11) | 1.34 | (0.53–2.5) | < 0.001 | < 0.001 | < 0.001 |
| No cardiac risk factor-no smoking | ||||||||||||
| Risk cardiac death (0.075%/Gy (RBE)) | 0.19 | (0.11–0.31) | 0.34 | (0.18–0.49) | 0.06 | (0.01–0.16) | 0.10 | (0.04–0.19) | ||||
| Risk cardiac death (1/N) | 525 | (932–321) | 293 | (556–203) | 1712 | (1333–632) | 994 | (2516–533) | ||||
| Cardiac risk factor(s) or smoking | ||||||||||||
| Risk cardiac death (0.3%/Gy (RBE)) | 0.76 | (0.43–1.25) | 1.36 | (0.72–1.97) | 0.23 | (0.03–0.63) | 0.40 | (0.16–0.75) | ||||
| Risk cardiac death (1/N) | 131 | (233–80) | 73 | (139–51) | 428 | (3333–158) | 249 | (629–133) | ||||
| Lungs_mean dose | 2.71 | (1.72–4.45) | 3.08 | (2.04–4.89) | < 0.001 | 1.78 | (1.05–2.80) | 1.44 | (0.79–2.34) | < 0.001 | < 0.001 | < 0.001 |
| No smoking | ||||||||||||
| Risk lung cancer death (0.06%/Gy(RBE)) | 0.16 | (0.10–0.27) | 0.18 | (0.12–0.29) | 0.11 | (0.06–0.17) | 0.09 | (0.05–0.14) | ||||
| Risk lung cancer death (1/N) | 616 | (969–375) | 542 | (817–341) | 936 | (1587–595) | 1161 | (2110–712) | ||||
| Continuing smoking | ||||||||||||
| Risk lung cancer death (0.88%/Gy(RBE)) | 2.38 | (1.51–3.92) | 2.71 | (1.80–4.30) | 1.57 | (0.92–2.46) | 1.26 | (0.70–2.06) | ||||
| Risk lung cancer death (1/N) | 42 | (66–26) | 37 | (56–23) | 64 | (108–41) | 79 | (144–49) | ||||
| Heart disease*lung cancer mortality: 1 − ∏(1 − p) (%) | ||||||||||||
| Low-risk patients (no smoking, no cardiac risk factors) (%) | 0.35 | (0.21–0.58) | 0.52 | (0.30–0.79) | < 0.001 | 0.17 | (0.07–0.33) | 0.19 | (0.09–0.33) | < 0.001 | < 0.001 | < 0.001 |
| No smoking, cardiac risk factors (%) | 0.92 | (0.53–1.51) | 1.55 | (0.84–2.26) | < 0.001 | 0.34 | (0.09–0.80) | 0.49 | (0.21–0.89) | < 0.001 | < 0.001 | < 0.001 |
| Smoking, no cardiac risk factors (%) | 2.57 | (1.62–4.22) | 3.04 | (1.97–4.78) | < 0.001 | 1.63 | (0.93–2.62) | 1.36 | (0.73–2.24) | < 0.001 | < 0.001 | < 0.001 |
| High-risk patients (smoking, cardiac risk factors) (%) | 3.12 | (1.94–5.11) | 4.03 | (2.50–6.19) | < 0.001 | 1.80 | (0.95–3.08) | 1.66 | (0.85–2.79) | < 0.001 | < 0.001 | < 0.001 |
Risk estimations for radiation-induced mortality, based on Taylor et al.7. Over a 30-year period for a 50-year old (reference) patient, the absolute risk of radiation-induced cardiac mortality was estimated 0.075%/Gy and 0.3%/Gy mean heart dose for patients without and with cardiac risk factors, respectively. For radiation-induced lung cancer mortality, the risk was estimated 0.06%/Gy and 0.88%/Gy mean lung dose (both lungs) for patients who never smoked or continued smoking since adolescence, respectively. The rows showing risk cardiac or lung cancer death (1/N) give the values of N where 1 out of N reference patients treated would die from radiation-induced cardiac injury or lung cancer, respectively, during a 30-year follow-up period. The heart disease*lung cancer mortality is the cumulative 30-year risk in (reference) patients who have cardiac risk factors and/or continue smoking. Mortality risks can be compared to the disease-specific survival benefit of adjuvant WBI + LNI including MI, which we assumed to be ≥ 8% at 30 years23. Legend: The columns ‘p-value DIBH-SB’, ‘p-value Ph/Pr DIBH’ and ‘p-value Ph/Pr SB’ represent the p-values of a t-test between the results of a comparison between (respectively): DIBH and SB, photon and proton for DIBH, and photon and proton for SB.