Plaquenil Does Not Increase the Risk of Prostate Cancer
Based on available evidence, hydroxychloroquine (Plaquenil) does not increase the risk of prostate cancer and may actually reduce the risk of metastatic disease and death in cancer patients.
Evidence from Drug Labeling
The FDA-approved prescribing information for Plaquenil explicitly states that "long-term studies in animals have not been conducted to evaluate the carcinogenic potential of PLAQUENIL" 1. Importantly, the drug label does not list cancer or prostate cancer as a known adverse effect or risk associated with hydroxychloroquine use. The primary concerns documented in the label relate to retinal toxicity, cardiac effects (QT prolongation), and hematologic abnormalities—not malignancy 1.
Clinical Evidence on Cancer Risk
The most relevant clinical study directly addressing this question is a large population-based cohort study that evaluated 8,999 individuals with connective tissue diseases exposed to hydroxychloroquine/chloroquine for at least 1 year compared to 24,118 unexposed individuals 2. This study found:
- No increased risk of non-skin cancers (adjusted sub-distribution hazard ratio: 1.04, p=0.54)
- No increased risk of hematological malignancies (adjusted sHR: 1.00, p=0.99)
- Significantly lower risk of metastatic cancer during the exposure period (adjusted sHR: 0.64 for overall population and 0.61 for those with incident cancers)
- Significantly lower risk of death in exposed individuals (adjusted HR: 0.90 in overall population and 0.78 in those with cancer) 2
Mechanism and Preclinical Data
While hydroxychloroquine has been studied as a potential therapeutic agent in prostate cancer through autophagy inhibition 3, 4, 5, 6, these studies focus on its anti-cancer properties rather than carcinogenic potential. The drug's mechanism involves autophagy inhibition and modulation of cellular pathways that could theoretically suppress rather than promote cancer development 2.
Important Caveats
The FDA label notes that chloroquine (a structurally related compound) "has been shown to be a catalytic inhibitor of DNA repair enzymes (topoisomerase II) and to produce weak genotoxic effects through this mode of action" 1. However, this theoretical concern has not translated into clinically observed increased cancer risk in long-term human studies 2.
In summary, patients taking Plaquenil should not be concerned about an increased risk of prostate cancer. The available evidence suggests no carcinogenic effect, and there may even be protective effects against cancer metastasis and mortality. Standard prostate cancer screening recommendations based on age, family history, and other risk factors should be followed regardless of Plaquenil use 7, 8, 9, 10, 11.