ESTRO 2024 Congress report
The Upper and Lower GI Poster discussion session was full beyond capacity 5 mins before the allotted start time. Those who were lucky enough to be present were not disappointed, with a range of different pathologies, methodologies and outcomes presented; a session where there was something of interest for everyone.
Two posters addressed the potential for predicting overall survival (OS) using lymphopenia during radiotherapy. Pim Damen looked at several different measures of lymphopenia in 1,339 oesophageal cancer patients reporting the one with the highest correlation with OS after multivariant analysis was the absolute lymphocyte count in week 3 of chemoradiotherapy (CRT). Landon Chan used slightly different methods looking at 107 patients with Hepatocellular Carcinoma (HCC). They identified patients who had Grade 3/4 lymphopenia after SABR treatment and reported lower survival in those who suffered lymphopenia. Both authors suggested we should move towards methods of mitigating radiotherapy-induced lymphopenia; however, this work does not tell us whether this is a predictive or prognostic biomarker, therefore further work is required to know whether these mitigation strategies will have any impact on survival.
Two posters aim to predict response to treatment. Ross McMahon kept up the systemic inflammatory response theme by looking at 278 patients receiving neoadjuvant treatment (NAT) for rectal cancer. They investigated whether a number of systemic blood parameters before and after NAT correlated with response and found that modified Glasgow Prognostic Score (mGPS), which uses a combination of albumin, CRP and CEA did so. Once again it was suggested that mitigation strategies such as immunomodulating mediation in patients with elevated systemic inflammatory response may affect outcomes, but further work is needed. Tiril Hillestad presented a poster investigating the ability of baseline and mid-treatment PET and MRI to predict response in anal cancer in <50 patients, they found a correlation between changes in ADC and tumour volume after 20Gy correlated with an improved disease-free survivalThis study adds to the numerous small contradicting trials looking at this question in multiple different tumour types. Different strategies are required moving forward to further address the question of radiological biomarkers. Our final poster looking at using factors during radiotherapy to predict outcomes was presented by Pieter Populaire. He presented a study looking at predicting cardiac complications following CRT and then surgery in oesophageal cancer. They presented data on 50 patients of whom 21 had suffered cardiac complications. They investigated several factors but ultimately showed that the optimal model for predicting cardiac complications included details on the left ventricle dose, age and BMI. The authors went on to suggest the next step would be to assess the impact of avoiding the left ventricle in radiotherapy planning.
There are settings where trials are not yet available or due to rarity of disease are not likely to occur. We heard about three such studies. Alessandra Arcelli presented multicentre retrospective real-world data in 125 patients treated with neo-adjuvant chemotherapy followed by SABR in pancreatic cancer, reporting an encouraging median OS of 23 months and a 2-year OS rate of 40.8%. This is valuable evidence of efficacy in a treatment we are already using, while trials are awaited. Sushma Agrawal used real-world data to look at the feasibility of neoadjuvant treatment in 217 locally advanced unresectable cholangiocarcinoma. The authors looked at how NAT affected the different radiological “inoperable” characteristics. They concluded that neoadjuvant treatment can result in an additional 10% respectability rate and the median OS in those who reached surgery was encouraging at 48 months. Rasika Sangle presented a single-centre retrospective study where all patients presenting with lateral pelvic lymph nodes from rectal primary were included. 57 and 131 patients received a radiotherapy boost to the lateral sidewall nodes versus no boost respectively, followed by surgery that may or may not include lateral sidewall excision. The local recurrence rate and OS were in favour of the boost (17.6% versus 0% local recurrences respectively). No differences were found in the radiotherapy or surgical morbidity reported, although in a retrospective trial this is inevitably underreported. Further details of which patients underwent lateral sidewall dissection are required but this is certainly an early indication of the benefit of lateral sidewall boost. Giuditta Chiloiro used real-world data from Italy to look at outcomes in rectal cancer relative to whether they were over or undertreated from the published ESMO guidance. They reported over-treatment in intermediate and locally advanced patients resulted in an improved overall survival, suggesting in their conclusion that higher doses and additional systemic agents are appropriate and result in improved OS in selected patients. However, it is likely the fittest patients were given the over-treatment and will inherently have lived longer. In addition, the important morbidity and quality of life measures are not addressed in this study. Finally Magdalena Fundowicz used the initial results from an IROCA audit of rectal and prostate radiotherapy to highlight the potential for audit, as a real-world data tool, to highlight variability in clinical practice and importantly areas for improvement.
Lastly, we had two prospective trials presented. Lidia Strigari presented a prospective trial where 101 patients with HCC were randomised between two different dosimetric approaches for the planning of their 90Y radionuclide selective internal radiotherapy (SIRT): a standard dosimetric approach (Arm A) or a novel voxel-based dosimetric approach (Arm B). The mean dose delivered was not discernibly different, however, the 1- and 2-year survivals were 63.6% versus 71.9% and 43.5% versus 58.2% for groups A and B respectively. While the overall results were not statistically significant, if there was a difference of >5% in the prescribed activity between the two strategies, the OS was statistically improved by the novel method. The authors should be commended for performing a clinically useful trial in this complex setting with little evidence to guide practice. Won Young Suh presented a prospective trial where 86 patients receiving radiotherapy to the liver had both CPAP and non-CPAP planning scans using abdominal compression. All the volumetric and dosimetric benefits measured, were improved by CPAP, leading the authors to suggest this should be investigated further. However, there are multiple motion management strategies available and whether CPAP is any improvement on these in terms of dosimetry, clinical toxicities, or ease of use remains to be seen.
Sometimes large phase III prospective trials are required, but this session showed that early work to lay the groundwork for future avenues of research, specifically small, focused studies answering immediate questions in poorly researched areas, and real-world data either in the form of a formal audit or a retrospective review to identify areas of good and poor care; are all vital aspects of research and development. Research in all forms, drives and contributes to our field and is all invaluable and necessary.
Rebecca Muirhead
Clinical Oncologist
Oxford University Hospitals NHS Foundation Trust,
Rebecca.muirhead@oncology.ox.ac.uk