ABSTRACT Objective: Colorectal cancer (CRC) is the world’s third most common type of cancer. Case studies have shown an inverse correlation between serum vitamin D levels and the incidence of human colorectal cancer. This study aims to assess vitamin D levels in patients who underwent colonoscopy for diagnostic colorectal cancer. Methods: This research is a cross-sectional study with subjects in this study were patients who came to the Digestive Surgery polyclinic and underwent a colonoscopy for diagnosis of colorectal cancer. Level of vitamin D was collected before the colonoscopy examination and categorized into three groups, vitamin D with a value of < 20 ng/mL indicate a deficiency, a level of 20 – 30 ng/mL as an insufficiency level, and a value > 30 ng/mL as a sufficient value. A colonoscopy examination was performed to obtain a diagnosis of colorectal cancer based on anatomical pathology examination. Result: Examination of vitamin D levels from 120 subjects showed the average vitamin level was 16.36 ng/mL, which indicates vitamin D deficiency levels. A total of 85 subjects (70.8%) showed vitamin D deficiency, as many as 24 (20%) showed vitamin D insufficiency levels, and only 11 study subjects (9.2%) showed sufficient vitamin D levels. The colonoscopy showed 60 subjects (50%) with colorectal cancer. The relationship between vitamin D levels and the diagnosis of CRC showed a value of p = 0.60 (p > 0.05). Conclusion: There is no significant difference between low levels of Vitamin D and the diagnosis of colorectal cancer patients.

Abstract Objective: Colorectal cancer (CRC) is the world’s third most common type of cancer. Data in Indonesia based on GLOBOCAN in 2020 shows CRC in the fourth position with around 35,000 new cases each year. The pathogenesis mechanisms of CRC are complex and heterogeneous, one of which is the involvement of NRAS (Neuroblastoma Rat Sarcoma viral oncogene homolog) mutations which play a role in cell growth regulation, as well as the expression of Human epidermal growth factor receptor 2 (HER2). This study aims to assess the association of subject characteristics and NRAS mutations with HER2 expression in CRC. Methods: This research is a cross-sectional study. There were 58 patients included in this study, they were colorectal cancer patients in the Digestive Surgery division at Dr. Hassan Sadikin Hospital. Examination of NRAS mutations was carried out by Polymerase Chain Reaction (PCR) from fresh tumour tissue obtained from surgery or colonoscopy. Meanwhile, HER2 examination used the Immunohistochemistry (IHC) method of paraffin blocks for anatomical pathology examination. Result: HER2 overexpression was found in 6/58 (10.3%) patients with CRC, and from 8 subjects with NRAS mutations, only 1 subject (1.7%) showed overexpression of HER2. Univariate analysis of HER2 expression showed no significant associations to age, sex, histologic feature, tumor location, and NRAS mutations. A significant association was found between HER2 expression and stadium of the CRC with p=0.001. Conclusion: There is no association between NRAS mutations and HER2 overexpression in colorectal cancer patients.