Strong evidence from randomized controlled trials (RCTs) indicates that oral antifungal drugs that are fully absorbed (fluconazole, ketoconazole, and itraconazole) or partially absorbed (miconazole and clotrimazole) from the gastrointestinal tract prevent oral candidiasis in people receiving treatment for cancer. Evidence also indicates that these drugs are significantly better at preventing oral candidiasis than drugs not absorbed from the gastrointestinal tract. No significant benefit was found for nystatin.

• A Cochrane review assessed the effectiveness of interventions (including placebo or no treatment) for the prevention of oral candidiasis for people with cancer receiving chemotherapy and/or radiotherapy [Clarkson, 2007]:
• The search strategy included the Cochrane Oral Health Group's Trials Register, CENTRAL, Medline, Medline Pre-indexed, Embase, INAHL, CANCERLIT, SIGLE, and LILACS up to April 2004.
• Trials were included if they were RCTs in people receiving chemotherapy or radiotherapy treatment for cancer. The interventions included drugs prescribed to prevent oral candidiasis. The primary outcome was prevention of oral candidiasis. Data were recorded on the following secondary outcomes if present: relief of pain, amount of analgesia, relief of dysphagia, incidence of systemic infection, duration of hospitalization (days), cost of oral care, quality of life, death, use of empirical antifungal treatment, toxicity, and compliance.
• Twenty-eight trials (n = 4226) met the inclusion criteria.
• The review compared the effect of absorbed antifungal drugs (e.g. fluconazole, itraconazole, ketoconazole) with antifungals which are not absorbed (e.g. nystatin, amphotericin B, chlorhexidine) or a placebo, or no treatment group (8 RCTs, n = 2014 people):
• The relative risk for absorbed drugs was 0.47 (95% CI 0.29 to 0.78). Nine people need to be treated to avoid one person getting oral candidiasis (NNT = 9, 95% CI 7 to 13). This NNT is an estimate calculated by using an incidence of 20% (chosen because 20% was the mid-range incidence figure in the control groups included in the meta analysis). The incidence in the control studies ranged from 5% (NNT = 37) to 60% (NNT = 3).
• Absorbed antifungals significantly reduced the proportion of people who developed oral candidiasis compared with non-absorbed antifungals (relative risk = 0.40, 95% CI 0.21 to 0.76).
• No significant benefit was shown for nystatin, although there was weak evidence that amphotericin B might be effective.
• No harms were reported.
• The effect of publication bias on these results is unknown. It is difficult to generalize the results because the trials were mainly in adults with haematologic cancer.
• The authors concluded that strong evidence from RCTs indicates that drugs that are fully absorbed or partially absorbed from the gastrointestinal tract prevent oral candidiasis in people receiving treatment for cancer. Evidence also indicates that these drugs are significantly better at preventing oral candidiasis than are drugs that are not absorbed from the gastrointestinal tract.