Complement Protein May Be Colorectal Cancer Biomarker

Screening for C3a-desArg could lead to earlier diagnosis of colorectal cancer

FRIDAY, Oct. 27 (HealthDay News) -- Elevated levels of complement C3a anaphylatoxin (C3a-desArg) in serum may be a useful biomarker for colorectal cancer and, if validated, could help physicians diagnose this cancer in its earlier stages, according to new research published in the October issue of Gastroenterology.

Jens K. Habermann, M.D., of the National Cancer Institute in Bethesda, Md., and colleagues used surface-enhanced laser desorption/ionization time-of-flight mass spectrometry to identify proteins among 58 people with colorectal cancer and 32 healthy controls. They then validated the proteins using enzyme-linked immunosorbent assays.

Patients with colorectal adenomas and carcinomas expressed higher levels of C3a-desArg in their serum than cancer-free individuals. The presence of this biomarker predicted colorectal cancer with a sensitivity of 96.8 percent and specificity of 96.2 percent, the report indicates. Moreover, researchers found increased blood levels of C3a-desArg in 86.1 percent of independently collected blood from patients with colorectal adenomas, and only 5.6 percent of sera were classified as normal.

"If confirmed, screening of serum levels of complement C3a-desArg could contribute to a reduction of the incidence of colorectal carcinomas and to a shift toward the diagnosis of cancer at earlier stages," the researchers conclude.

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