San Francisco, California—Study findings presented at the 2020 Virtual ASCO Annual Meeting suggest that methylated DNA markers (MDMs) in plasma are a promising method for accurately detecting distant recurrent colorectal cancer (rCRC).

“[MDMs] are broadly informative for early detection of [CRC] but have not been extensively studied for post-treatment surveillance and disease monitoring,” wrote Hao Xie, MD, PhD, Mayo Clinic, Rochester, Minnesota, and colleagues, who sought to evaluate the feasibility of using new CRC-associated MDMs to detect distant rCRC in plasma.

Dr Xie et al selected a panel of 13 MDMs that were discriminant for primary CRC, and analyzed the MDMs blindly in a cross-sectional analysis of plasma samples from 60 healthy controls, 60 patients with resected CRC and no evidence of disease, and 40 patients with rCRC after primary tumor resection. All study participants had a median age of 55 years.

All patients underwent plasma-derived carcinoembryonic antigen (CEA) measuring, and a prediction algorithm of MDMs (with and without CEA) for the end point of rCRC relative to healthy controls was developed via random forest modeling.

Algorithm accuracy was summarized as sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) with 95% CIs in the test set.

According to the findings, a single MDM with the highest AUC was significantly better than CEA (P = .02), and CEA did not further improve the performance of the panel of 13 MDMs, a cross validation revealed (P = .2).

Using the cross-validated panel of MDMs, the investigators were able to detect rCRC liver metastases, lung metastases, and peritoneal/nodal metastases with 96%, 78%, and 57% sensitivity, respectively.

Lesions that had a RECIST sum >4 cm and ≤4 cm were detected with 94% and 78% sensitivity, respectively.

“Novel MDMs in plasma detect rCRC with promising accuracy. The clinical utility of MDMs for non-invasive post-treatment surveillance and treatment monitoring in CRC warrants further evaluation in longitudinal studies with sufficient follow-up to exclude sub-clinical recurrence in those with [no evidence of disease],” Dr Xie and co-investigators concluded.—Hina M. Porcelli

Xie H, Mahoney DW, Foote PH, et al. Novel methylated DNA markers in plasma detect distant recurrence of colorectal cancer. Presented at: the 2019 Genitourinary Cancers Symposium; February 14-16, 2019; San Francisco, CA. Abstract 4088.