BackgroundHealth-related quality of life (HRQOL) is a vital assessment to demonstrate the achievement in pediatric cancer care parallels that of medical treatment. The Pediatric Quality of Life Inventory (PedsQL) 3.0 Cancer Module in the Thai Version has become a standard tool to access the HRQOL among Thai children with cancer and their families. This study aimed to explore the HRQOL and factors related to HRQOL among pediatric oncology patients using the PedsQL 3.0 Cancer Module.MethodsIn 2018–2019, a single-institution, cross-sectional study was conducted among children with cancer and their families in Bangkok, Thailand. A paired-sample t-test was performed to evaluate the differences between the HRQOL scores of the child and parents' reports. Linear regression was used to evaluate factors associated with HRQOL and which particular domains of the PedsQL 3.0 Cancer Module were influenced.ResultsEighty-five children with cancer and their families were enrolled. The patients’ mean age was 10.82 ± 5.48 years. The most common cancer types included acute lymphoblastic leukemia (n = 32, 67%), central nervous system tumors (n = 13, 15%), osteosarcoma (n = 10, 27%) and neuroblastoma (n = 9, 24%), in rank. The mean HRQOL scores in child and parent reports were 74.37 ± 15.7 and 70.42 ± 17.15, respectively (p = 0.034). Factors negatively correlated to HRQOL in parent reports were the number of outpatient visits (p = 0.019) and hospital admissions (p = 0.002). The number of hospitalizations was the only independent factor that affected HRQOL (p = 0.044). The number of outpatient visits and/or hospital admissions was influenced by pain and hurt, nausea, procedural anxiety and communication domains (p < 0.05). Only the number of hospitalizations was an independent factor influencing the procedural anxiety domain in HRQOL (p = 0.005).ConclusionHRQOL among Thai children with cancer was desirable from both children's and parent's perspectives. Differences between child and parent HRQOL scores were observed. The number of outpatient visits and hospital admissions affected HRQOL, particularly in the procedural anxiety aspect.Trial registrationThai Clinical Trials Registry (TCTR) Number: TCTR20200904001 (04/09/2020), https://www.thaiclinicaltrials.org/.