Improving malodour management in advanced cancer: a 10-year retrospective study of topical, oral and maintenance metronidazole.

Objectives: To explore the relative effectiveness of topical or oral metronidazole used for malodour in necrotic cancers and to propose a protocol for metronidazole usage in managing malodour.

Methods: A retrospective case note review of the management of malodour over 10 years comparing outcomes with topical, intermittent and maintenance oral metronidazole.

Results: Among 179 patients treated for malodour, the commonest primaries were cervical (45%), and head and neck cancers (40%). Outcomes were poor during the period when only topical or intermittent oral metronidazole was used. Topical use gradually decreased (97% vs 55%) and the proportion of patients receiving maintenance oral metronidazole increased (0% in 2003-2004 vs 93% in 2011). Concurrently, there was reduction in documented malodour (12.5% of visits per patient in 2003-2004 vs 1.5% in 2011, p<0.01).

Conclusions: Our data support formulary guidelines recommending maintenance metronidazole for recurrent malodour. Dimethyl trisulfide, a product of anaerobic necrosis causes malodour and can attract maggot-producing flies to decaying tissues. Therefore, to reduce anaerobic malodour in vulnerable settings, we propose a ladder for metronidazole titration. High-risk patients should start with 400 mg thrice daily ×7 days and continue 200 mg once daily. The SNIFFF severity (Smell-Nil, Faint, Foul or Forbidding) can guide follow-up dosage: 200 mg once daily to continue for nil or faint smell; breakthrough courses of 400 mg thrice daily ×1 week for foul smell and 2 weeks for forbidding smell, followed by 200 mg once daily.The effectiveness and limitations of maintenance metronidazole and the SNIFFF ladder should be prospectively evaluated.