Incidental Finding of Elevated Serum Cartilage Oligomeric Matrix Protein (sCOMP) in Knee Osteoarthritis Patient with Undiagnosed Colon Cancer: A Case Report

BACKGROUND: The clinical utility of cartilage oligomeric matrix protein (COMP) as a diagnostic and prognostic biomarker is currently under intense study. COMP has been associated primarily with musculoskeletal disorders such as rheumatoid and osteoarthritis (OA) or muscular and ligament trauma. Aside from its established role as a biomarker of arthritis, an increasing number of studies have also suggested the role of COMP in tumorigenesis, based on findings of its expression in breast, prostate, and colon cancers. CASE PRESENTATION: We described the case of a 61-year-old man with knee osteoarthritis and was prescribed physical therapy and a course of prolotherapy injection. We found elevated sCOMP levels in our patient (twice higher than average). After a month of follow-up, he was diagnosed with colorectal cancer. CONCLUSION: It makes us wonder about other conditions of the patients. There is no standard COMP parameter to differentiate OA patients from colorectal cancer patients, but it considers the increase is higher in colorectal cancer patients. We suggest to clinicians who use the COMP level to monitor OA condition to be aware of other conditions when the level is much higher than average OA patients.