REporting recommendations for tumor MARKer prognostic studies (REMARK)
The Strategy Group of the PACCT and a working group of an NCI-EORTC collaboration developed the following guidelines for the information that should be included in all publications about tumor markers. These recommendations were published simultaneously in British Journal of Cancer, European Journal of Cancer, Journal of Clinical Oncology, Journal of the National Cancer Institute, and Nature Clinical Practice Oncology. The recommendations are being placed on this website to encourage the research community and members of journal editorial boards to ensure that more complete information will be included in publications about prognostic markers. Comments should be sent to: Dr. Lisa McShane (firstname.lastname@example.org) or Dr. Douglas Altman (email@example.com).
The recommendations are organized according to a typical format of articles appearing in biomedical journals. Specifically, we cover information relevant to Introduction, Materials and Methods, Results, and Discussion sections. Further details and explanatory material will be provided in a subsequent manuscript. The full publication can be found here.
- State the marker examined, the study objectives, and any pre-specified hypotheses.
Materials and Methods
- Describe the characteristics (e.g., disease stage or co-morbidities) of the study patients, including their source and inclusion and exclusion criteria.
- Describe treatments received and how chosen (e.g., randomized or rule-based).
- Describe type of biological material used (including control samples) and methods of preservation and storage.
- Specify the assay method used and provide (or reference) a detailed protocol, including specific reagents or kits used, quality control procedures, reproducibility assessments, quantitation methods, and scoring and reporting protocols. Specify whether and how assays were performed blinded to the study endpoint.
- State the method of case selection, including whether prospective or retrospective and whether stratified (e.g. by stage of disease, age). Specify the time period from which cases were taken, the end of the follow-up period, and the median follow-up time.
- Precisely define all clinical endpoints examined.
- List all candidate variables initially considered for inclusion in models.
- Give rationale for sample size; if the study was designed to detect a specified effect size, give the target power and effect size.
Statistical analysis methods
- Specify all statistical methods, including details of any variable selection procedures and other model-building issues, how model assumptions were verified, and how missing data were handled.
- Clarify how marker values were handled in the analyses; if relevant, describe methods used for cutpoint determination.
- Describe the flow of patients through the study, including the number of patients included in each stage of the analysis (a diagram may be helpful) and reasons for dropout. Specifically, both overall and for each subgroup extensively examined report the numbers of patients and the number of events.
- Report distributions of basic demographic characteristics (at least age and sex), standard (disease-specific) prognostic variables, and tumor marker, including numbers of missing values.
Analysis and presentation
- Show the relation of the marker to standard prognostic variables.
- Present univariate analyses showing the relation between the marker and outcome, with the estimated effect (e.g., hazard ratio and survival probability). Preferably provide similar analyses for all other variables being analyzed. For the effect of a tumor marker on a time-to-event outcome, a Kaplan-Meier plot is recommended.
- For key multivariable analyses, report estimated effects (e.g., hazard ratio) with confidence intervals for the marker and, at least for the final model, all other variables in the model.
- Among reported results, provide estimated effects with confidence intervals from an analysis in which the marker and standard prognostic variables are included, regardless of their statistical significance.
- If done, report results of further investigations, such as checking assumptions, sensitivity analyses, and internal validation.
- Interpret the results in the context of the pre-specified hypotheses and other relevant studies; include a discussion of limitations of the study.
- Discuss implications for future research and clinical value.