Radiotherapy Induced Xerostomia (RIX)
“Is the most significant long-term complication of radiotherapy for tumours in head and neck cancer” (HNC); (Kumar et al 2011).
Dry Mouth develops as radiation preferentially kills the serous glands (Parotid and Submandibular) that produce the thin watery element of saliva. The mucous secreting Sublingual gland is more resistant to radiation. The end result is xerostomia, i.e. dryness of the mouth caused by altered or insufficient saliva to keep the mouth wet. It is a chronic lifelong problem for a high proportion of HNC patients affecting “64% of the long-term survivors” (Wijers et al 2002).
RIX is associated with thick viscous mucus, oral inflammation and infections. Patients with RIX find it difficult to eat, swallow and talk and can suffer from the additional problems of accelerated tooth decay and halitosis. A Cochrane Review of topical lubricants, coating agents, saliva substitutes and lozenges concluded that “there is no strong evidence that any topical treatment is effective for relieving the sensation of dry mouth” (Furness et al 2011).
- S Kumar et al. Salivary Gland and Associated Complications in Head and Neck Cancer Therapy. CDA Journal 2011; 30:639-647.
- Wijers O, et al. Patients with head and neck cancer cured by radiation therapy: a survey of the dry mouth syndrome in long-term survivors. Head Neck. 2002;24: 737–747.
- Furness, S. et al 2011. Interventions for the Management of Dry Mouth: Topical Therapies. The Cochrane Collaboration and published in The Cochrane Library, 2011, Issue 12.
In the video below you can witness the moment a droplet of Visco-ease make contact with a droplet of 5% Mucin on a microscope slide, immediately changing its fluidity:
As lamellar bodies in the mouth maintain the fluidity of mucus and lubricate the mouth, replacement therapy with the mimetic Visco-ease (OXB/1-20) has the potential to modify the consequences of RIX. Working on this premise, Lamellar and The Beatson completed two studies on clinical material that definitively demonstrated that Visco-ease was able to restore the fluidity of RIX saliva close to that of pre-treatment levels. The results of the larger and most recent study are available in the Open Access Dry Mouth Report and ICHNO Poster (see below).
The video below shows a patient’s RIX saliva sample on an inclined plane. The sample was taken after 6 weeks of radiotherapy treatment, it is clear from the video that the drops of saliva are not moving down the vertical plane, this is indicative of RIX saliva. In the video you will see the saliva being treated firstly with a saline spray and then sprayed with Visco-ease at 20mg/ml. The video clearly shows the effect Visco-ease has on the RIX saliva which supports the results found in the Beatson study report:
As a result of the positive outcome of the RIX study the Beatson team have submitted abstracts of the report for oral and poster presentations to multiple oncology and radiotherapy, cancer supportive care conferences:
Supportive Care in Cancer
In parallel to presenting the results of these studies at conferences the study results have been published in ‘Supportive Care in Cancer‘ (left).
In addition to RIX, Dry Mouth is a common complaint found often among older adults, typically affecting 30% of the adult population over 65 and is a common side effect of many medications e.g. for bladder or respiratory conditions.
As described above, Lamellar will be running a controlled clinical trial at the Beatson in 2015, randomising 35 patients who are about to begin RT for the treatment of HNC. Active or placebo will be given to the patients for the 6 weeks duration of RT treatment with either active or placebo.
The purpose of the clinical trial is to observe the relationships between patient’s disease specific oral quality of life and RIX symptoms in response to treatment with Visco-ease and placebo administered to patients suffering from RIX.
Primary Objective: Assess subjective efficacy of Visco-ease (OXB/1-20) compared to placebo in patients with RIX, using the validated GRIX (Groningen Quality of Life Questionnaire).
Secondary Objective: Ongoing post-market surveillance of Adverse Events.