Subgroup analyses in randomized phase III trials of systemic treatments in patients with advanced solid tumours: a systematic review of trials published between 2017 and 2020.

BACKGROUND: Subgroup analyses of randomized controlled trials are very common in oncology; nevertheless, the methodological approach has not been systematically evaluated. The present analysis was conducted with the aim of describing the prevalence and methodological characteristics of the subgroup analyses in randomized controlled trials in patients with advanced cancer. METHODS: A systematic literature search using PubMed was carried out to identify all phase III randomized controlled trials conducted in adult patients affected by locally advanced or metastatic solid tumours, published between 2017 and 2020. RESULTS: Overall, 253 publications were identified. Subgroup analyses were reported in 217 (86%) publications. A statistically significant association of presence of subgroup analysis with study sponsor was observed: subgroup analyses were reported in 157 (94%) for-profit trials compared with 60 (70%) non-profit trials (P < 0.001). Description of the methodology of subgroup analysis was completely lacking in 82 trials (38%), only cited without methodological details in 100 trials (46%) and fully described in 35 trials (16%). Forest plot of subgroup analyses for the primary endpoint was available in 195 publications (77%). Among publications with reported forest plots, the median number of subgroups for primary endpoint was 19 (range 6-78). Out of the 217 publications with subgroup analyses, authors discuss the heterogeneity of treatment effect among different subgroups in 173 publications (80%), although a formal test for interaction for subgroup analysis of primary endpoint was reported for at least one variable only in 60 publications (28%). Correction for multiplicity was explicitly carried out only in nine trials (4%). CONCLUSIONS: The very high prevalence of subgroup analyses in published papers, together with their methodological weaknesses, makes advisable an adequate education about their correct presentation and correct reading. More attention about proper planning and conduction of subgroup analysis should be paid not only by readers, but also by authors, journal editors and reviewers.

Deficiencies in health-related quality-of-life assessment and reporting: a systematic review of oncology randomized phase III trials published between 2012 and 2016.

Quality of life (QoL) is a relevant end point and a topic of growing interest by both scientific community and regulatory authorities. Our aim was to review QoL prevalence as an end point in cancer phase III trials published in major journals and to evaluate QoL reporting deficiencies in terms of under-reporting and delay of publication. All issues published between 2012 and 2016 by 11 major journals were hand-searched for primary publications of phase III trials in adult patients with solid tumors. Information about end points was derived from paper and study protocol, when available. Secondary QoL publications were searched in PubMed. In total, 446 publications were eligible. In 210 (47.1%), QoL was not included among end points. QoL was not an end point in 40.1% of trials in the advanced/metastatic setting, 39.7% of profit trials and 53.6% of non-profit trials. Out of 231 primary publications of trials with QoL as secondary or exploratory end point, QoL results were available in 143 (61.9%). QoL results were absent in 37.6% of publications in the advanced/metastatic setting, in 37.1% of profit trials and 39.3% of non-profit trials. Proportion of trials not including QoL as end point or with missing QoL results was relevant in all tumor types and for all treatment types. Overall, 70 secondary QoL publications were found: for trials without QoL results in the primary publication, probability of secondary publication was 12.5%, 30.9% and 40.3% at 1, 2 and 3 years, respectively. Proportion of trials not reporting QoL results was similar in trials with positive results (36.5%) and with negative results (39.4%), but the probability of secondary publication was higher in positive trials. QoL is not included among end points in a relevant proportion of recently published phase III trials in solid tumors. In addition, QoL results are subject to significant under-reporting and delay in publication.