Sample Size Calculation in Oncology Trials: Quality of Reporting and Implications for Clinical Cancer Research.

OBJECTIVES: Sample size calculation (SSC) is a pivotal step in clinical trial conception and design. Herein, we describe the frequency with which oncology phase III trials report the parameters required for SSC. MATERIALS AND METHODS: We systematically searched for phase III trials published in 6 leading journals, which were accompanied by editorials from January 2008 to October 2011. Two blinded investigators extracted required and optional parameters for SSC according to the primary endpoint. RESULTS: We retrieved 140 eligible phase III trials. The median target sample size was 596 subjects (50 to 40,000); in 66.4% of cases, the number of enrolled subjects was at least 90% of the target. The primary endpoint was a continuous variable in 5.7%, categorical in 30.0%, and a time-to-event variable in 64.3% of phase III trials. Although nearly 80% reported a target sample size, only 27.9% of the trials provided all the required parameters for proper SSC. The most commonly reported parameters for sample size computation were α (93.6%) and ß (90.7%) errors. The parameters least reported were the expected outcomes in the control or experimental groups, each provided in only 57.9% of trials. CONCLUSIONS: The quality of SSC reporting in phase III cancer trials is poor. Such incomplete reporting may compromise future study designs, pooling of data, and interpretation of results. Lack of transparency in SSC reporting may also have ethical implications.

Phase II trial of metformin and paclitaxel for patients with gemcitabine-refractory advanced adenocarcinoma of the pancreas.

BACKGROUND: In patients with adenocarcinoma of the pancreas, there are no standard second-line regimens. Many pre-clinical studies have shown that metformin alone or when combined with paclitaxel has antitumour effects on this tumour. We have tested here the combination of paclitaxel and metformin for patients with gemcitabine-refractory pancreatic cancer. METHODS: An uncontrolled phase II trial was carried out based on a two-stage Simon's design, with metformin and paclitaxel for patients with locally advanced or metastatic pancreatic cancer whose disease had progressed during first line treatment with a gemcitabine-based regimen. The primary endpoint was the disease control rate at eight weeks as per response evaluation criteria in solid tumours (RECIST) 1.1. Patients received paclitaxel 80 mg/m(2) weekly for three weeks every 28 days and metformin 850 mg p.o. t.i.d. continuously until progression or intolerance state was reached. RESULTS: Twenty patients were enrolled from July 2011 to January 2014: N = 6 (31.6%) achieved the primary endpoint, with all presenting stable disease. Median overall survival (OS) was 128 days (range 17-697) and the median progression free survival (PFS) was 44 days (range 14-210). Eight patients (40%) presented treatment-related G3-4 toxicities with the most common one being diarrhoea. CONCLUSIONS: Despite the encouraging pre-clinical evidence of the antitumour activity of metformin in adenocarcinoma of the pancreas, the primary endpoint of the disease control rate was not met. Besides, the treatment combination was poorly tolerated and could not be studied further. This study highlights the importance of performing clinical trials to reassure preclinical or observational data.

Self-reported conflicts of interest of authors, trial sponsorship, and the interpretation of editorials and related phase III trials in oncology.

PURPOSE: Growing participation by industry in cancer research has resulted in increased reporting of conflicts of interest (COI). We aimed to test any association between authors' conclusions and self-reported COI or trial sponsorship in cancer studies. METHODS: Editorials and related phase III trials published in six clinical oncology journals in the last 3.5 years were analyzed independently by two investigators who classified study conclusions according to authors' endorsement of the experimental therapy. Logistic regression multivariable models were used to assess predictors of favorable conclusions of editorialists and of phase III authors. RESULTS: From January 2008 to October 2011, 1,485 articles were retrieved: 150 phase III trials and 150 editorials were eligible. Among the phase III trials, 82 (54.7%) had positive results, and 78 (52.0%) were entirely or partially funded by industry. Any COI were disclosed in 103 phase III trials (68.7%) and in 71 editorials (47.3%). Multivariable analysis showed that phase III trial results were the only significant predictor for a positive conclusion by trial authors (odds ratio [OR], 92.2; 95% CI, 19.7 to 431.6; P < .001). Sponsorship did not predict for positive conclusion by phase III authors (OR, 0.86; 95% CI, 0.3 to 2.5; P = .788). The only factor associated with positive conclusions by editorial authors was a positive conclusion by phase III trial authors (OR, 36.3; 95% CI, 6.8 to 194.2; P < .001). CONCLUSION: The interpretation of recently published phase III cancer trials by their authors or by editorialists was not influenced by financial relationships or industry sponsorship. Increased awareness of COI policies may have led to more integrity in cancer research reporting.