Primary tumor resection (PTR) does not improve overall survival (OS) in asymptomatic patients with colon or high rectal cancer who have synchronous unresectable metastases, new research suggests.
These findings, from a pooled analysis of the SYNCHRONOUS and CCRe-IV trials, were presented at the 2022 ASCO Annual Meeting by Jurgen Weitz, MD, of University Hospital Carl Gustav Carus in Dresden, Germany.
The SYNCHRONOUS trial (Identifier: ISRCTN30964555) enrolled patients with newly diagnosed colon or high rectal cancer who had unresectable synchronous metastases. They were randomly assigned to undergo PTR or to a no-resection arm. Both arms received chemotherapy, which was administered after surgery in the PTR arm.
The CCRe-IV trial (ClinicalTrials.gov Identifier: NCT02015923) had a similar design. In both trials, the primary endpoint was OS.
Dr Weitz presented data on 393 patients — 295 from the SYNCHRONOUS trial and 98 from the CCRe-IV trial. Overall, 206 patients were assigned to chemotherapy without resection, and 187 were assigned to chemotherapy with PTR.
The median age at baseline was 69 years in both treatment groups, and a majority of patients were men (66%-67%). Roughly 45% of patients in each group had right-sided cancer, around 60% had 1 metastatic site, and about 95% had liver metastasis.
Resection of the primary tumor was ultimately performed in 87.7% of patients assigned to the PTR group and 2.9% of those assigned to the no-resection group. Among the patients who ultimately underwent resection, laparotomy was performed in 54.3% of the PTR group and 80% of the no-resection group.
There were more patients in the PTR group than in the no-resection group who did not receive chemotherapy — 24.1% and 6.4%, respectively. In both groups, the most common first-line chemotherapy regimens were an oxaliplatin doublet and an irinotecan doublet. In the majority of patients, chemotherapy was combined with bevacizumab or an EGFR antibody.
There was no significant difference in median OS between the PTR and no-resection groups — 16.7 months and 18.6 months, respectively (hazard ratio [HR], 0.946; P =.658). Findings were similar in subgroup analyses.
However, OS was significantly worse for patients who did not receive chemotherapy (HR, 5.32; P <.001), and OS decreased with each additional year of age (HR, 1.013; P =.033).
Serious adverse events (AEs) were more common in the no-resection group than in the PTR group — 18.0% and 10.2%, respectively. The most common serious AEs were gastrointestinal tract-related toxicities — 10.7% and 4.8%, respectively.
Patients in the no-resection group were more likely to experience ileus/bowel obstruction (41.9% vs 9.1%), and patients in the PTR group were more likely to experience bowel perforation (13.6% vs 7%).
“Resection of the primary tumor does not prolong overall survival in asymptomatic colon/high rectal cancer patients with distant unresectable disease,” Dr Weitz said. “The most important factor regarding overall survival is administration of chemotherapy.”
Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.
Rahbari NN, Biondo S, Feißt M, et al. Randomized clinical trial on resection of the primary tumor versus no resection prior to systemic therapy in patients with colon cancer and synchronous unresectable metastases. Presented at ASCO 2022; June 3-7, 2022. Abstract LBA3507.