Factors affecting the non-publication of clinical trials of prevalent urological cancer

Clinical trials (CTs) are critical in understanding and managing cancer. However, despite being completed, CT results are often unpublished, compromising the ability to glean useful information from them. This study aimed to evaluate factors influencing the non-publication of urological oncology clinical trials.

We conducted a comprehensive search of ClinicalTrials.gov to identify CTs focused on urological cancers completed between 2000 and 2020. We used the National Clinical Trial (NCT) identifier number to check whether the trial was published.

9,145 oncology CTs were conducted between 2000 and 2020, of which 8.39% (n = 767) focused on urological cancers, and 47.2% (n = 362) of these trials remained unpublished. Univariable analysis revealed that trials with a sample size of less than 50 and phase 4 were significantly associated with non-publication p < 0.001. In contrast, trials involving triple masking, a higher number of agents, and those conducted in High-Income Countries were associated with a higher likelihood of publication p < 0.05. Multivariable analysis demonstrated that trials enrolling more than 50 patients and employing three or more agents, along with triple and quadruple masking, had higher odds of being published (OR = 1.62; 95%CI (1.22–2.16), 1.89; 95%CI (1.10–3.27), 3.04; 95%CI (1.44–6.44), 5.62; 95%CI (1.72–18.37), and 5.41; 95%CI (1.76–16.67), p < 0.05, respectively). However, trials conducted in low-middle-income Countries had lower odds of publication (OR = 0.26; 95%CI (0.08–0.87), p = 0.02).

We found that almost one-half (47.2%) of all completed urologic oncology clinical trials are not published in a PubMed-indexed journal. This non-publication rate represents a significant loss of scientific knowledge and progress. We identified several key variables including sample size.