Investigation of autoantibodies in colorectal cancer patients and gastric cancer patients using the indirect immunofluorescence method

Objective: Colorectal cancer (CRC) and gastric cancer (BC) are among the most common cancers in the population and are among the most common causes of death. Although many parameters have been identified for the diagnosis and prognosis of these cancers, their asymptomatic nature in the early stages necessitates further research. Our study aimed to investigate the relationship between antinuclear antibody (ANA) and its subparameters, histopathology results, biochemical test results, and the presence of cancer and its prognostic factors in CRC and BC patients. Materials and Methods: Our study was conducted at Karadeniz Technical University Faculty of Medicine and Medical Park Karadeniz Hospital between January 2024 and April 2025 with newly diagnosed CRC (60 patients), BC patients (30 patients), and a control group (60 volunteers). The presence and patterns of ANA were examined using indirect immunofluorescence, and antibodies to extractable nuclear antigens (ENA) were examined using immunoblot. Histopathology and biochemistry test results were obtained from hospital records. Results: ANA positivity was found to be 62.2% in cancer patients and 36.6% in anti-ENA positivity. In the control group, ANA positivity rate was found to be 28.3%, while the anti- ENA positivity rate was found to be 13.3%. ANA positivity was found to be higher and statistically significant in the all cancer group, CRC group, and MC group compared to the control group. Anti-ENA positivity was found to be higher and statistically significant in the all cancer group, CRC group compared to the control group, while no statistically significant difference was found in the MC group compared to the control group. Speckled, nucleolar, and intercellular bridge patterns were found in the CRC group; speckled, spindle fibers, reticular cytoplasm, dense fine speckled cytoplasm, and intercellular bridge patterns were found to be statistically significant in the MC group compared to the control group. Mi-2 and PM/Scl100 were detected more frequently in the CRC group; Mi-2, PM/Scl100, and CENP B were detected more frequently in the MC group compared to the control group and were found to be statistically significant. Additionally, ANA, anti-ENA, and lactate dehydrogenase (LDH) were found to be independent predictors of cancer presence. Anti-ENA positivity was associated with MSH-2 (MutS homolog 2) and MSH-6 (MutS homolog 6). No association was found between tumor staging and the presence of autoantibodies. Conclusion: In our study, it was found that the presence of autoantibodies may be a predictor in the detection of CRC and MC. Autoantibodies can be used to predict the presence of cancer in daily practice by correlating with the patient's history, clinic and other laboratory findings.