Reporting of preclinical tumor-graft cancer therapeutic studies

Characterize the parameters of reporting tumor-graft experiments for oncologic drug development.

Using Institute of Scientific Information impact factors, we identified the most-cited medical and oncology journals with tumor-graft experiments in murine models. For each article, the characteristics of the experimental design, outcome measurements, and statistical analysis were examined.

We examined 145 articles describing tumor-graft experiments from October through December 2008. The articles spanned a range of disease types, animal models, treatments and delivery methods. One hundred (69%) articles were missing information needed to replicate the experiments. Outcome measurements included: tumor size (83%), biological changes (57%), and survival or cure-rate outcomes (28%). Thirty-three percent did not specify how tumor size was measured and 30% were missing the formula for evaluating volume. Only 14% utilized appropriate statistical methods. Ninety-one percent of studies were reported as positive and 7% reported with mixed positive-negative results; only 2% of studies were reported negative or inconclusive. Twenty-two articles from 2012 showed improvement in the utilization of statistical methods (35% optimal, p = 0.05) but had a similar fraction with experimental design issues (82%; p = 0.32) limiting reproducibility and 91% had positive results.

Tumor-graft studies are reported without a set standard, often without the methodological information necessary to reproduce the experiments. The high percentage of positive trials suggests possible publication bias. Considering the widespread use of such experiments for oncologic drug development, scientists and publishers should develop experimental and publication guidelines for such experiments to ensure continued improvements in reporting.