Insufficient evidence for interventions to prevent dry mouth and salivary gland dysfunction post head and neck radiotherapy.

Abstract

Data sourcesCochrane Oral Health's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase, CINAHL, EBSCO (Cumulative Index to Nursing and Allied Health Literature, LILACS, BIREME, Virtual Health Library (Latin American and Caribbean Health Science Information database), Zetoc Conference Proceedings, the US National Institutes of Health Ongoing Trials Register, (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases.Study selectionThe review included randomised controlled trials, irrespective of their language of publication or publication status. Participants could be outpatients or inpatients. The review included trials comparing any pharmacological agent regimen, prescribed prophylactically for salivary gland dysfunction prior to or during radiotherapy, with placebo, no intervention or an alternative pharmacological intervention. Comparisons of radiation techniques were excluded.Data extraction and synthesisStandard Cochrane methodological processes were followed.ResultsThirty-nine studies that randomised 3520 participants were included; the number of participants analysed varied by outcome and time point. The studies were ordered into 14 separate comparisons with meta-analysis only being possible in three of those. We found low quality evidence to show that amifostine, when compared to a placebo or no treatment control, might reduce the risk of moderate to severe xerostomia (grade 2 or higher on a 0 to 4 scale) at the end of radiotherapy (risk ratio (RR) 0.35, 95% confidence interval (CI) 0.19 to 0.67; P = 0.001, three studies, 119 participants), and up to three months after radiotherapy (RR 0.66, 95% CI 0.48 to 0.92; P = 0.01, five studies, 687 participants), but there is insufficient evidence that the effect is sustained up to 12 months after radiotherapy (RR 0.70, 95% CI 0.40 to 1.23; P = 0.21, seven studies, 682 participants). We found very low quality evidence that amifostine increased unstimulated salivary flow rate up to 12 months after radiotherapy, both in terms of mg of saliva per five minutes (mean difference (MD) 0.32, 95% CI 0.09 to 0.55; P = 0.006, one study, 27 participants), and incidence of producing greater than 0.1 g of saliva over five minutes (RR 1.45, 95%CI 1.13 to 1.86; P = 0.004, one study, 175 participants).However, there was insufficient evidence to show a difference when looking at stimulated salivary flow rates. There was insufficient (very low quality) evidence to show that amifostine compromised the effects of cancer treatment when looking at survival measures. There was some very low quality evidence of a small benefit for amifostine in terms of quality of life (ten-point scale) at 12 months after radiotherapy (MD 0.70, 95% CI 0.20 to 1.20; P = 0.006, one study, 180 participants), but insufficient evidence at the end of and up to three-month post radiotherapy. A further study showed no evidence of a difference at 6, 12, 18 and 24-month post radiotherapy.There was low quality evidence that amifostine is associated with increases in: vomiting (RR 4.90, 95% CI 2.87 to 8.38; P < 0.00001, five studies, 601 participants); hypotension (RR 9.20, 95% CI 2.84 to 29.83; P = 0.0002, three studies, 376 participants); nausea (RR 2.60, 95% CI 1.81 to 3.74; P < 0.00001, four studies, 556 participants); and allergic response (RR 7.51, 95% CI 1.40 to 40.39; P = 0.02, three studies, 524 participants).The authors founded insufficient evidence (that was of very low quality) to determine whether or not pilocarpine performed better or worse than a placebo or no treatment control for the outcomes: xerostomia, salivary flow rate, survival and quality of life. There was some low quality evidence that pilocarpine was associated with an increase in sweating (RR 2.98, 95% CI 1.43 to 6.22; P = 0.004, five studies, 389 participants).The authors found insufficient evidence to determine whether or not palifermin performed better or worse than placebo for: xerostomia (low quality); survival (moderate quality); and any adverse effects. There was also insufficient evidence to determine the effects of the following interventions: biperiden plus pilocarpine, Chinese medicines, bethanechol, artificial saliva, selenium, antiseptic mouthrinse, antimicrobial lozenge, polaprezinc, azulene rinse and Venalot Depot (coumarin plus troxerutin).ConclusionsThere is some low quality evidence to suggest that amifostine prevents the feeling of dry mouth in people receiving radiotherapy to the head and neck (with or without chemotherapy) in the short- (end of radiotherapy) to medium-term (three-month post radiotherapy). However, it is less clear whether or not this effect is sustained to 12-month post radiotherapy. The benefits of amifostine should be weighed against its high cost and side effects. There was insufficient evidence to show that any other intervention is beneficial.