Mini oral session: GI, lower digestive

Prof Dr Hans Prenen, medical oncologist at the University Hospital Antwerp selected three abstracts from the mini oral session on lower GI tumours. 

The OPERA trial, published in The Lancet last year, explores neoadjuvant therapy for rectal cancer with a focus on organ preservation. Patients with early-stage (T2, T3) and small, node-positive tumours were randomised after chemoradiotherapy to receive either an external radiotherapy boost or brachytherapy. Results showed a five-year local relapse rate of 39% in the external radiotherapy group compared to 17% in the brachytherapy group, indicating a clear local control benefit with brachytherapy. Organ preservation was achieved in 80% of patients in the brachytherapy group, rising to over 90% for tumours under 3 cm. No significant difference in distant metastasis rates was observed between groups. These findings suggest that brachytherapy can improve local control and organ preservation in rectal cancer, although its adoption is limited by the need for specialised expertise. Nonetheless, the results support further integration into clinical practice. 

The second trial focuses on the use of immunotherapy for MSI-high rectal cancer in the neoadjuvant setting. Immunotherapy has demonstrated significant efficacy in metastatic MSI-high colon cancer, often yielding complete responses. Based on this, a trial was conducted to assess its potential in localised MSI-high rectal cancer. The trial explored the use of immunotherapy in the neoadjuvant setting, allowing patients to potentially avoid surgery for one year. Importantly, this was not a randomised trial; instead, treatment decisions were left to the discretion of the investigators. Of the 35 patients, 17 underwent surgery, while 18 did not. The results showed approximately 80% DFS and 94% OS, confirming the efficacy of immunotherapy in this setting. Although promising, randomised trials are needed to further validate its role in MSI-high rectal cancer.

The CITRIC trial, conducted in the metastatic colon cancer setting, investigates the re-challenge of anti-EGFR therapy. Previous data on anti-EGFR re-challenge have mostly been retrospective, prompting the need for a randomised trial. In this study, patients who had undergone first-line anti-EGFR treatment plus chemotherapy, followed by a second-line therapy, and became refractory, were considered for re-challenge. A total of 58 patients, confirmed as ctDNA RAS wild-type via liquid biopsy, were randomised to receive either irinotecan plus cetuximab or treatment of the investigator’s choice. The trial reported responses in four out of 31 patients, but PFS remained short in both arms, showing only a trend toward improvement. While the trial suggests some potential for anti-EGFR re-challenge, selecting the right patients for this approach remains challenging.