The following is a summary of “Role of Tumor-informed Personalized Circulating Tumor DNA Assay in Informing Recurrence in Patients With Peritoneal Metastases From Colorectal and High-grade Appendix Cancer Undergoing Curative-intent Surgery,” published in the December 2023 issue of Surgery by Dhiman, et al.
For a study, researchers sought to find out how a personalized, tumor-informed circulating tumor DNA (ctDNA) assay can help predict recurrence in people who have peritoneal metastases (PM) from colorectal (CRC) and high-grade appendix (HGA) cancer after cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). More than half of people with CRC/HGA-PM get it again after the best CRS-HIPEC. It takes so long to find a return and start new treatments because axial imaging and diagnostic biomarkers are not very sensitive. Plasma ctDNA could be a useful way to track how well treatment is working and whether the cancer comes back after being removed.
People with CRC or HGA-PM who had successful CRS-HIPEC and multiple ctDNA tests after surgery were included. Patients whose ctDNA levels went up after surgery were compared to those whose levels stayed the same or couldn’t be found. The main results were the number of patients who had a relapse and disease-free survival (DFS). The secondary results were overall mortality, ctDNA sensitivity, wait time, and how well ctDNA worked compared to carcinoembryonic antigen. About 130 serial postresection ctDNA tests [median 4; interquartile range (IQR), 3 to 5] were done on 33 patients (n = 13 CRC, n = 20 HGA) who had completion of cytoreduction-0/1 CRS. The patients were followed up on average for thirteen months. 90% of the 19 patients whose ctDNA levels went up got it again, but only 21% of those whose levels stayed the same (n = 14, < 0.001).
The stable group did not reach the median DFS of 11 months (IQR, 6 to 12), but the growing group did (P = 0.01). The most important thing linked to DFS was an increasing ctDNA level (hazard ratio: 3.67, 95% CI: 1.06–12.66, P = 0.03). When it came to identifying return, higher ctDNA levels were 85% sensitive and 84.6% specific. A ctDNA lead time of 3 months was the middle number (IQR, 1 to 4). Carcinoembryonic antigen wasn’t as sensitive as ctDNA (50% less sensitive). The study showed that measuring ctDNA over time was a good way to tell if a patient with CRC or HGA-PM who has had successful removal will have the cancer come back. It also has the potential to help plan future clinical trials and lead to more studies.
