Relationship of quinolinic acid and serotonin with depression and pain degree in cancer pain patients: a cross-sectional study

Introduction: Chronic pain requires a thorough assessment if it persists in patients with cancer. Depressive disorder is one of the psychosocial problems that can occur in cancer patients. Depressive disorders affect up to 34.4% of patients with cancer in Indonesia, causing increased morbidity and complicating the management of patients. Quinolinic acid (QUIN) and serotonin (5-HT) are chemicals that can affect pain perception and depressive disorders. This study aims to analyze the relationship between quinolinic acid and serotonin levels with depression and pain degree in cancer pain patients.Methods: A cross-sectional study design was conducted at the Palliative Polyclinic of Dr. Soetomo Surabaya General Hospital, Indonesia. Patients were collected with purposive sampling. The patient's quinolinic acid and serotonin plasma were collected through blood samples and assessed using enzyme-linked immunosorbent assay (ELISA) method. Spearman's comparison test determined the correlation between quinolinic acid and serotonin levels with depression and pain degree.Results: A total of 76 cancer patients were included in this study. The cancer types reported were pelvic cancer (23 patients, 30.3%), head and neck cancer (21 patients, 27.6%), abdominal cancer (ten patients 13.2%), breast cancer (seven patients, 9.2%), lung cancer (five patients, 6.6%), skin cancer (three patients, 3.9%), and other types of cancers (seven patients, 9.2%). As many as 24 patients (31.6%) had mild depression and only three patients (3.9%) experienced major depression. Mild pain was reported by 47 patients (61.8%) and 11 patients (14.5%) suffered from severe pain. Spearman's comparison test was conducted on quinolinic acid and serotonin levels against depression degree and pain degree, resulting in a weak correlation.Conclusion: Quinolinic acid and serotonin levels are related to depression and pain degree in cancer pain patients (p<0.05), though with a weak correlation. However, further study is needed to confirm the findings of this study.