The standards for including or excluding a study were set according to the PICOS components. With regards to Population, studies had to be conducted solely on children or adolescents, from 1 up to 19 years old. Participants were incorporated, at any point during the course of their treatment, from cancer diagnosis to ongoing therapy, to long-term follow-up after treatment, or death. The participants recruited must have received a medical diagnosis or positive diagnostic testing of cancer, of any type. Regarding Intervention, only studies using interventions to reduce symptoms including distress, anxiety or depression for children diagnosed with cancer were taken into consideration in this systematic review paper. Interventions included should have involved a psychological intervention of either music therapy, video gaming and technological nature, or of hypnosis and other relaxation techniques. As far as Outcome a study should have to examine at least one of the desirable outcomes (distress, anxiety, depression) to be included. All types of anxiety whether it was procedural, state, or treatment-related were included in the outcomes of the review in order to examine the full aspect of the anxiety at every stage of the cancer treatment the patient experiences. Young patients may experience anxiety about medical treatments or methods, hospital admission, clinic appointments, or recrudescence, so full aspect examination of the disorder was required. Various types of distress that were manifested either as somatic or psychological were incorporated in the paper, with a range of tools for measuring it. For depression, mainly the common Childhood Depression Inventory (CDI) and Beck Depression Inventory tools have been used for evaluating the studies included. Lastly, with regards to Studies, RCTs with a matched control group were sought. Identified research protocols that did not present satisfactory data were also excluded. Additionally, studies had to be published solely in the English language by journals with a peer-review process.

An orderly literature inspection was performed within Pub Med, Web of Science & SCOPUS databases without date constraint. Search filter for English language only was applied and no other filter prior or after the search. The keywords used in each database are stated below in the following combination. (Childhood cancer OR Paediatric Oncology OR paediatric cancer OR pediatric oncology)AND (child*OR adolescent* OR teen*OR paediatric)AND (mental health issues)AND (anxiety OR depression OR Distress OR stress)AND (supportive therapy OR palliative care OR music*OR video game OR game*OR virtual). Terms were searched for in each title and abstract, and in the keywords of each study, and were adapted accordingly to each electronic database. The researchers separately searched introduction sections and reference lists of papers that were to be included for supplementary studies consistent with to the question of the review.

The data were collected independently by two researchers (C.Z. and M.M.). Data gathered from the studies included: 1) participant demographics (e.g. sex, age and participants’ number), 2) methodology (e.g., interventions’ and follow-up measurements’ type and length), and 3) results (e.g., psychological consequences on distress, anxiety and depression). Quality assessment of individual studies was conducted according to the Cochrane Collaboration’s tool for assessing risk of bias (Higgins et al., 2011) by two researchers (C.Z. and M.M.).

Initial search yielded 468 papers. The reviewing investigators concluded in 17 randomized control trials. The complete screening process is illustrated in Figure 1. Table 1 presents the information gathered from the studies, making allowance for trial intervention, design and type of study, participants’ demographics, type of control group, outcomes measures, timeline of follow-up calculation and main judgements.

A total number of 572 pediatric oncology patients with mean age ranging between 5 to 19 years old participated in the studies. All papers consisted of patients with childhood cancer only and excluded cancer survivors. The individuals who participated in the studies received diverse forms of psychological intercessions. The intercession applied can be categorized to 3 subcategories of interventions: music therapy interventions (n = 5), relaxation and hypnosis interventions (n = 7), technology and video games interventions (n = 5). Results and main findings of the studies indicate that 14 out of 17 studies reviewed in this paper reported statistically significant improvements in at least one of the examined psychological outcomes. Studies were compared and analyzed across their own category and type of intervention.

The outcome and tools of measurement mentioned in the following table of studies and results are in regard to the desired psychological outcomes (distress, anxiety, and depression) that this review examines. There are also additional outcomes of psychological nature that several studies are reporting, but they are not mentioned in the following table as they are not in the reviewing interest of this paper.

Figure 2 illustrates the results of the quality evaluation of the involved studies based on the Cochrane Collaboration’s tool for assessing risk of bias (Higgins et al., 2011). The synopsis of the “risk of bias using the Cochrane’s ROB 2 tool for every study” is entailed in this review, as shown in Table 2. The five risks of bias areas are individually evaluated, and then rated as a total for a comprehensive risk of bias for every study. From the table of risk of bias, the quality of evidence in every study is evident. Five out of the 17 trials evaluated to be of “Low Risk” thus indicating a higher quality of trials evidence, 7 evaluated to be of “Some