Session from Sunday 5 May at ESTRO 2024
ESTRO 2024 Congress report
On the central day of the congress, Markus Diefenhardt from Goethe University in Frankfurt, Germany, presented new insights into the randomised phase III chemoradiotherapy plus induction or consolidation chemotherapy as total neoadjuvant therapy (TNT) for locally advanced rectal cancer (CAO/ARO/AIO-12) trial through the use of a generalised pairwise comparison (GCP). The study compared two TNT sequences in intermediate/high-risk rectal cancer: induction chemotherapy before chemoradiotherapy (CRT) (arm A) and CRT before consolidation chemotherapy (arm B). Although arm B showed a higher pathological complete response, a GCP analysis of multiple outcomes, including overall survival (OS), local recurrence, distant metastasis, remission, long-term quality of life (QoL) and toxicity, revealed no significant differences. The authors highlighted the importance of improving long-term patient-reported QoL and the possibility of performing the analysis with a ranking of the outcomes based on the importance stated by patients.
Two studies focused on the toxicity profile of different radiotherapy techniques. Alexander Valdman from Karolinska University Hospital, Sweden, presented an early safety analysis of the ongoing randomised phase II PRORECT trial, in which hypofractionated (5x5GyE) proton beam therapy (PBT) was compared with photon therapy for locally advanced rectal cancer. Although Dmean to the spinal canal was significantly higher in the PBT arm, no cases of acute lumbosacral plexopathy were found (n=40).
Max Tanaka from the Netherlands Cancer Institute compared the preoperative acute toxicity that occurred during the use of 3D-CRT or intensity-modulated radiotherapy/volumetric arc therapy (IMRT/VMAT) using data from the RAPIDOtrial. They found no significant differences in severe toxicities, although the use of IMRT/VMAT was linked with higher rates of nausea, vomiting and fatigue in the TNT (experimental) arm. The author commented that this could be explained by the fact that there was no optimised plan for those organs at risk.
Alessandra Castelluccia from Rome explored the use of dose-escalated, short-course radiotherapy in a TNT protocol for rectal cancer. A simultaneous, integrated stereotactic boost was given to the rectal lesion of 40Gy (8Gy/fraction) at 80% isodose with an MR-guided adaptive technique followed by a maximum of three cycles of chemotherapy. They showed no grade >3 toxicity (n=39), and a 31% pathological complete response rate. Compared with other TNT protocols that included several cycles of oxaliplatin-based chemotherapy, this study resulted in a similar rate of pathological response and limited toxicity.
Ross McMahon, of Glasgow, UK, reported on the predictive value of CT-derived body composition parameters for radiotherapy response in locally advanced rectal cancer. The study found that a visceral fat to subcutaneous fat ratio ≥0.4 was linked to incomplete neoadjuvant therapy response. This ratio, which is associated with higher levels of systemic inflammation, suggests that a pro-inflammatory environment may drive tumour resistance.
Lastly, Ahmed Allam Mohamed presented a study on the prognostic significance of HIF-1α in anal cancer (AC). This study investigated HIF-1α expression in AC patients and found that higher HIF-1α levels (>50%) were correlated with poorer median OS of 34.6 months and disease-free survival (DFS) of 33.8 months, whereas those with low levels of HIF-1α had not reached median OS or DFS. The results suggest that HIF-1α is a potential prognostic biomarker.
Camilla Kronborg
Consultant, associate professor, PhD
Danish Centre for Particle Therapy | Aarhus University Hospital
Palle Juul-Jensens Boulevard 99 | DK-8200 Aarhus
Denmark
E-mail: camkro@rm.dk
Letizia Deantonio, MD
Senior consultant, privat dozent
Oncology Institute of Southern Switzerland, Faculty of Biomedical Sciences, University of Southern Switzerland
Bellinzona, Switzerland
e-mail: letizia.deantonio@eoc.ch