Usually, routine colorectal cancer (CRC) screening starts at 45 years and older with occult blood testing followed by colonoscopy. The U.S. Preventive Services Task Force recommends that adults aged from 45 to 75 years should be screened for colorectal cancer. Have you reached 45 years or more (1)? Did you receive a fecal occult blood test (FOBT)? A study found that after 10 years of CRC screening, the cumulative probability of a true-positive colorectal cancer result was 0.6% with annual FOBT screening and 0.4% with biennial screening and the true-positive rate of FOBT was only 1.9 per 1000 tests for people aged 65 years who undergone FOBT followed by sigmoidoscopy. Thus, FOBT was ensured to reduce colorectal cancer mortality whereas it also couldn’t replace nor reduce the rate of colonoscopy nor sigmoidoscopy (2).
What is the most challenging part you face when performing colonoscopy? Most people fear pain, bleeding, bloating and diarrhea post sigmoidoscopy or colonoscopy. Unfortunately, many people don’t show compliance when subjected to sigmoidoscopy.
What's the future? What do people need to do to overcome this dilemma? Blood based tests with reduced cost and time effectiveness in addition with significant true results are needed to decrease the need for sigmoidoscopy and colonoscopy, also to overcome the low true positive FOBT results. (2) Our team of researchers studied a panel of blood based biomarkers namely eotaxin-1 which was found to be present in high serum levels in colorectal cancer (3), macrophage inflammatory protein-1 beta (MIP-1 beta) an inflammatory cytokine found to be highly expressed in CRC tissues (4), granulocyte colony-stimulating factor (G-CSF) which is also highly expressed in CRC tissues and promote cancer migration (5) and finally vascular endothelial growth factor (VEGF-A) which was found to be an independent prognostic factor in patients with non-metastatic colorectal cancer (6). When we studied the serum levels of these four biomarkers in early stage of colorectal cancer patients and compared their overall combined performance with FOBT we found that the ROC curve generated cut-off value for serum eotaxin-1 was (113.31 pg/mL), serum MIP-1β (96.07 pg/mL), serum G-CSF (23.35 pg/mL) and serum VEGF (195.94 pg/mL). It can be noted that MIP-1β has the highest sensitivity (91.43%) and NPV (92.5%). While VEGF has the highest specificity (92.31%) and PPV (85.2%). Stool occult blood was false positive for CRC diagnosis in 33 subjects out of 52 non-malignant subjects i.e. (63.5%). Thus, the studied serum markers were more sensitive and specific in detecting CRC patients, in addition the area under the ROC curve for the combined panel of the studied markers (eotaxin-1, MIP-1β, G-CSF and VEGF-A) was 0.863 which was better than area under the ROC curve 0.597 for routinely used occult blood in the stool. Additionally, on combining the ROC curve of the studied panel together with occult blood, the area under the curve was increased to 0.875 thus if combined with the occult blood test they may increase the performance of FOBT in the diagnosis of colorectal cancer. Furthermore, the used multiplex bead assay is a promising technique in measuring multiple biomarkers at the same time while being cost efficient and highly sensitive (7). Previous studies were done in the USA (8), Malaysia (9), Poland (10) and Japan (11) on various combinations of serum biomarker in colorectal cancer patients that augment our results. We hope more work can be done to implement these biomarkers in routine colorectal cancer screening practice.