Pharmaceutical industry funding and chemotherapy trials for prostate cancer: A systematic review

Introduction: Clinical trials are increasingly supported by industries while previous studies have shown that industry-supported studies have more favorable results than studies with other sources of funding. In the present study, we investigated the association of industrial funding on the results of clinical trials regarding chemotherapy in prostate cancer. Methods: A systematic literature search was performed in the Cochrane Library, MEDLINE, and EMBASE to identify clinical trials comparing chemotherapy with treatments such as hormone therapy, surgery, radiotherapy, and placebo in patients with metastatic or non-metastatic prostate cancer. Data were extracted by two reviewers on the financial resources and the positive or negative results of chemotherapy in each study. The quality of articles was evaluated and compared based on Cochrane Critical Appraisal Tool. The trials were divided into two groups; industry funded and those not funded by industry. Association of industry funding and positive outcome was presented as odds ratio. Results: In this study, out of the 91 studies, 80.2% were funded by pharmaceutical companies and 19.8% were funded by government agencies. The end result of 61.6% of the studies funded by pharmaceutical companies was an increase in survival due to chemotherapy, whereas only 27.8% of the studies sponsored by government agencies reported positive results (P-value=0.010). In fact, industry-funded trials more often presented statistically significant positive results for survival (OR: 4.17; CI, 1.34–12.99). In general, there was no significant difference in the degree of bias between the two groups. Conclusion: According to this study, despite of the similar quality of studies funded by pharmaceutical companies and government agencies, positive results were more common in studies related to pharmaceutical companies. Therefore, this point should be taken into account when making a decision on the best treatment approach.