Confirm or refute the harm of antioxidant supplements during chemotherapy
Half of patients take antioxidant vitamins during chemotherapy. One good observational study suggests they raise recurrence by 40%. Patients deserve a definitive answer, and it can be obtained cheaply by adding supplement tracking to trials already running.
The DELCaP study nested in a breast cancer chemotherapy trial found that antioxidant supplements (vitamins A, C, E, carotenoids, coenzyme Q10) taken before and during chemotherapy were associated with a 41% higher recurrence and 40% higher mortality, with similar signals for vitamin B12, iron and omega-3. Randomised harm has been shown for beta-carotene in smokers and for antioxidants during head and neck radiotherapy. A randomised trial of antioxidants during chemotherapy is now ethically difficult; the pragmatic path is prospective supplement capture in every adjuvant trial and a pre-registered pooled analysis, plus a randomised trial of a stop-supplement counselling intervention.
- Misinformation and unproven therapies · Patients are sold unproven treatments and frightened away from proven ones.
- Weak real-world evidence and registries · We do not reliably know what happens to patients after approval, so we cannot tell which drugs deliver in practice.
- Toxicity and quality of life are undervalued · Trials measure how long people live, not how they live. Side-effects are under-reported and under-treated.