This study is reported according to the PRISMA statement (30) and the guidelines for reporting meta-epidemiological methodology research (31). We developed the protocol a priori and made it available via Open Science Framework (OSF) (https://osf.io/6ejh9/?view_only=4320d9fbe4134ca88422d1eaf3d5b44a; DOI 10.17605/OSF.IO/6EJH9). No major changes were introduced to the protocol throughout the conduct of this study.
Search strategy and screening
An information specialist designed (LN), tested and implemented a systematic search for RCTs published in the MEDLINE, EMBASE, and CENTRAL databases between 2010 and 2017. We selected 2010 because the CONSORT statement (27) was launched in 2010 (http://www.consort-statement.org). Additional file 1 presents the search strategies for MEDLINE, EMBASE and CENTRAL.
We used the management software Rayyan (32)) for independent screening of title and abstract. Pairs of researchers discussed disagreements, with resolution by an independent third researcher where necessary.
We included RCTs meeting the following criteria:
The study population had to consist of adult (older than 18 years old) survivors of any type of cancer. A survivor was defined according to the Centers for Disease Control and Prevention (CDC), as anyone who has been diagnosed with cancer, from the time of diagnosis through the rest of life (33).
We included RCTs evaluating the effects of exercise training interventions for cancer survivors. Exercise was defined as any body movement that increases energy expenditure and that is planned, structured, repetitive, and purposive in the sense that it aims to improve or maintain one or more components of physical fitness (i.e., cardiorespiratory endurance, muscular endurance, muscular strength, body composition, and flexibility) (34;35).
We accepted for inclusion any exercise training interventions involving different training modes, such as aerobic, resistance and flexibility training, as well as yoga, Qi-gong and Tai-Chi (3;11). Further, the exercise training interventions could be conducted in different settings (such as clinical or community) or mediums (such as water or land). Because of the review’s focus on the reporting of exercise training interventions, we excluded RCTs that evaluated recreational physical activity interventions rather than a structured exercise program, as well as trials reporting on manual therapy (e.g., joint mobilization techniques and therapeutic massage), cognitive-behavioral interventions, and mixed interventions that combined exercise with other therapeutic approaches, such as psychotherapy or diet or dietary advice/counseling. Finally, we excluded trials that compared exercise training with pharmacological and surgical treatments.
We included studies with non-exercise intervention comparisons (such as conventional care) or other exercise interventions (e.g., aerobic versus resistance training). Where trials compared two exercise interventions, both interventions were included in the analysis. For example, if there were five trials of exercise versus no intervention, and two trials of aerobic training versus resistance training, then the review would report on the completeness of reporting of nine exercise interventions.
We did not use the outcomes measured by the studies to determine eligibility because this study focused solely on the completeness of reporting of the intervention.
Study design and type of publication
The study design had to be a RCT. If there was any dispute about the eligibility of a trial’s design, we referred to the National Cancer Institute’s definition (36). Only full-text publications were included in the review. If the findings from a certain RCT were reported in two or more publications, pairs of reviewers evaluated all publications related to the study, retrieved the trial registry number if available, and included the primary/original publication, which was deemed to be the first publication of the study and the one with the most complete reporting of the exercise interventions.
We considered for inclusion studies published in English, Spanish, Italian, Portuguese and Scandinavian languages.
Data extraction and management
Characteristics of the included studies
We extracted the following information: publication year, country, trial registry, study name, original publication/companion, sample size (total analyzed), type of cancer, treatment stage, control group(s), exercise mode, length (weeks, with the minimum value reported in case of range), frequency (sessions/week), and setting.
TIDieR checklist and calculation of completeness of reporting
A pair of researchers from a pool of four worked independently to apply the TIDieR checklist to the included RCTs. As recommended by the TIDieR committee, the checklist is completed following the TIDieR guide (29), which contains an explanation and elaboration for each item. All the items were rated Yes/No. Only items that were clearly met were rated Yes; any that were partially met were rated No. We extracted data only from the full-text paper. Pairs of researchers discussed disagreements, with those outstanding resolved by an independent third researcher. Each item on the TIDieR checklist made up one component of the score of completeness of reporting, except for the multicomponent items. Item 5 contributed two components and Item 8 contributed four components. Therefore, the score was calculated as how many of 16 items were reported (as shown in Table 1) and converted to a percentage.
Overall and subgroup analyses
We calculated completeness of reporting in the RCTs as the number of the 16 criteria met, and presented these as percentages for each TIDieR item. We presented separate data for the subgroups of breast cancer and non-breast cancer trials.
Table 1. Final version of the TIDieR checklist used in this study (16 items)
1. Brief name
Provide the name or a phrase that describes the intervention
Describe any rationale, theory, or goal of the elements essential to the intervention
3. What (Materials)
Describe any physical or informational materials used in the intervention
4. What (procedures)
Describe each of the procedures, activities, and/or processes used in the intervention
5. a. Who provided (disciplinary background)
Describe the disciplinary background of the provider
b. Who provided (expertise, experience, or specific training)
Describe the expertise, experience, or specific training of the provider
Describe the modes of delivery
Describe the type(s) of location(s) where the intervention occurred
8. a. When and how much (frequency)
Describe the number of times the intervention was delivered (e.g., number of sessions)
b. When and how much (length)
Describe the number of weeks/months the intervention lasted
c. When and how much (duration)
Describe the duration of each session (e.g., minutes /session)
d. When and how much (intensity)
Describe the intensity at which the exercise was practiced
If the intervention was planned to be personalized, titrated or adapted, then describe what, why, when, and how
If the intervention was modified during the course of the study, describe the changes
11. How well (planned)
If intervention adherence or fidelity was assessed, describe how and by whom, and if any strategies were used to maintain or improve fidelity, describe them.
12. How well (actual)
If intervention adherence or fidelity was assessed, describe the extent to which the intervention was delivered as planned.