“Liquid biopsy” assays of circulating tumor cells (CTCs) should be conducted using arterial rather than venous blood specimens, according to a small study of 17 patients with metastatic uveal melanoma.
“Liquid biopsy” assays of circulating tumor cells (CTCs) should be conducted using arterial rather than venous blood specimens, according to a small study of 17 patients with metastatic uveal melanoma, published in EBioMedicine.1
Standard practice is for CTCs to be measured using venous blood specimens. The new findings might help explain why CTCs are not always detected in patients with aggressive metastatic cancers.
“Our data indicate that arterial blood specimens might be a better source of circulating uveal melanoma cells,” wrote researchers from the Sidney Kimmel Medical College at Thomas Jefferson University in Philadelphia.
In patients with multiple liver metastases, melanoma CTCs were more sensitively detected in blood specimens drawn from common femoral arteries (100% of specimens) than in blood from antecubital veins (52.9%), the study authors reported.
Metastatic tumor burden of the liver did not correlate with the number of arterial CTCs. But patients who also had metastatic tumors in other organs, in addition to the liver, had higher numbers of arterial CTCs than patients with liver-only metastatic disease (P = .003), the researchers noted.
Nine of the study participants had undergone systemic anticancer therapy and 13 had undergone liver targeted treatments, the study authors reported.
Arterial blood can be more difficult to collect. But given the results of their pilot study, the authors suggested that arterial blood should be evaluated as a sample source for measuring CTCs.1
The presence of CTCs in patients with metastatic breast, colorectal, or prostate cancer, has been shown to be associated with shorter patient survival times. High CTC counts (>5 cells in 7.5 mL venous blood) have been shown to indicate refractory metastatic disease, lead study author Takami Sato, MD, noted.
“If we can validate this approach for uveal melanoma, we hope to be able to catch cancer before it develops into metastatic disease,” Sato said. “Our research raised a concern that venous blood specimens, which are tested as the standard practice for CTC measurement, might not be the best source for CTC detection.”2