Abstract 722P
Background
Up to 70% of HCC patients present with unresectable diseases. While stereotactic body radiotherapy (SBRT) has emerged as a safe and feasible option among small tumors, dose-individualization is pivotal among large, advanced HCC patients with especially compromised liver reserves. We established TCP and normal tissue complication (NTCP) models for patients treated with IHRT to evaluate the dose-response and toxicity relationships to improve clinical outcome.
Methods
TCP and NTCP models were generated from a prospectively collected database of 186 consecutive patients receiving IHRT of median physical dose at 32Gy in 6–10fractions during Jan 2012–May 2017. NTCP was based on the generalized Lyman-Kutcher-Burman model. Common liver toxicities of albumin-bilirubin (ALBI), Child-Pugh (CP) score changes were chosen as clinical endpoints. All patients had advanced HCC >5cm and were ineligible for curative interventions. IHRT was delivered by SBRT techniques with doses individualized by tumor volume, V30 or mean dose of uninvolved liver and bowel proximity.
Results
Median tumor size was 11.4cm (range: 5.1–25.7cm) and median planning target volume was 992.0mL (range: 70.0–5266.0mL). The dose corresponding to 50% probability (D50) of 6-month local control was achievable at 23.6Gy10 (2Gy-equivalent dose, EQD2) with an actuarial 1-year local control of 88.0% (95% CI: 82.9–93.1%). The dose corresponding to 50% of complication probability rates (TD50) at 3 months for CP score ≥2 points and ALBI ≥1 grade decline were 60.5Gy2.5 and 79.5Gy2.5 (EQD2) respectively. Table: 722P
| TCP | |
| Local Control Probability at 6 months | Overall (n=186) |
| D50 (EQD2, a/b=10) | 23.6 |
| NTCP | |
| Complication Probability at 3 months | |
| CP Decline ≥ 2 points (TD50; EQD2, a/b=2.5) | 60.5 |
| ALBI Decline ≥ 1 Grade (TD50; EQD2, a/b=2.5) | 79.5 |
Conclusions
An enhanced understanding of dose-response relationships and normal tissue complications among large, advanced HCCs is crucial to facilitating personalized treatment and bridging unmet needs. Modest IHRT doses achieved favourable local control with manageable toxicities and represents a promising strategy.
Clinical trial identification
Institutional Review Board (IRB)-approved [IRB number: New Territories West Cluster Clinical Research Ethics Committee (NTWC/CREC/18064)].
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.