Interventions for cough in cancer

Cough is a common symptom in patients with malignancies, especially in patients with lung cancer. Cough is not well controlled in clinical practice and clinicians have few management options to treat it.

The primary objective of this review was to determine the effectiveness of interventions, both pharmacological and non-pharmacological, (other than chemotherapy and external beam radiotherapy) in the management of cough in malignant disease (especially in lung cancer).

Databases searched included: The Cochrane Central Register of Controlled Trials (CENTRAL) and the Database of Abstracts of Reviews of Effectiveness (DARE) (The Cochrane Library issue 4, 2009); MEDLINE (1966 to May 2010); EMBASE (1980 to May 2010); CINAHL (1980 to May 2010); PSYCHINFO (1980 to May 2010); AMED (1985 to May 2010); SIGLE (1980 to May 2010); British Nursing Index (1985 to May 2010); CancerLit (1975 to May 2010). We searched for cough suppressants, antitussives and other drugs with antitussive activity as well as non-pharmacological interventions (see Appendices 1-4 for search terms).

We selected randomised controlled trials (RCTs) and clinical trials (quasi-experimental trials, and trials where there is a comparison group but no mention of randomisation) in participants with primary or metastatic lung cancer or other cancers.

Two review authors independently assessed titles and abstracts of all studies, and extracted data from all selected studies before reaching consensus. A third review author arbitrated with any disagreement. Meta-analysis was not attempted due to the heterogeneity of studies.

Seventeen studies met inclusion criteria and examined either brachytherapy, laser or photodynamic therapy (eight studies) or a variety of pharmacological therapies (nine studies). Overall, there was absence of credible evidence and the majority of studies were of low methodological quality and high risk of bias. Brachytherapy seemed to improve cough in a variety of doses in selected participants, suggesting that possibly the lowest effective dose should be used to minimise side effects. Photodynamic therapy was examined in one study, and while improvements in cough were observed, its role over other therapies for cough is unclear. Some indication of effect was observed with morphine, codeine, dihydrocodeine, levodropropizine, sodium cromoglycate and butamirate citrate linctus (cough syrup), although all studies had significant risk of bias.

No practice recommendations could be drawn from this review. There is an urgent need to increase the number and quality of studies evaluating the effects of interventions in the management of cough in cancer.