Treating head and neck cancer with intensity-modulated radiotherapy (IMRT) that spares the major salivary glands, reduces xerostomia (dry mouth which can affect speech and swallowing) and improves quality of life compared with conventional radiotherapy, according to the self-reported experience of patients published in The Lancet Oncology.

These findings, from the largest randomised trial of IMRT in head and neck cancer so far, will improve the function and quality of life for thousands of patients with squamous-cell carcinoma of the head and neck (HNSCC), the most common type of head and neck cancer worldwide.

Conventional radiotherapy for head and neck cancers damages the parotid salivary glands which secrete saliva, and dry mouth is the most frequently reported late side-effect. A lack of saliva prevents patients from eating solid food and speaking normally, and can accelerate development of tooth decay.

In contrast, IMRT can deliver precise radiation to tumours while minimising exposure to healthy surrounding tissues. Small phase 2 studies have shown better saliva function in patients given IMRT compared with conventional radiotherapy.

The PARSPORT randomised phase 3 trial was funded by Cancer Research UK and designed to confirm whether IMRT reduces the incidence of severe dry mouth compared with conventional radiotherapy. Between January 2003 and December 2007, 94 patients with HNSCC were enrolled from six radiotherapy centres across the UK and randomly assigned to IMRT (47 patients) or conventional radiotherapy (47).

Saliva flow was measured before treatment and at regular intervals after radiotherapy, and side-effects assessed using the Late Effects of Normal Tissue (LENT SOMA) scale. Quality of life was evaluated using self-reported questionnaires completed at regular intervals after treatment for up to 2 years.

Overall, patients treated with IMRT experienced significantly less dry mouth than those given conventional radiotherapy, had significantly better recovery of saliva flow, and a consistently higher quality of life score.

At 12 months, grade 2 or worse dry mouth was reported by 74% of patients receiving conventional radiotherapy compared with 39% given IMRT, and at 24 months in 83% of patients versus 29%.

At 1 year, unstimulated saliva flow was recorded in nearly half of patients in the IMRT group compared with none in the conventional radiotherapy group.

Fatigue during treatment was the only grade 2 or worse adverse event that was significantly greater in patients treated with IMRT (74%) than those given conventional radiotherapy (41%).

The authors suggest that these results are likely to be applicable to all head and neck tumours for which conventional radiotherapy is used.

They conclude: "Sparing the parotid glands with IMRT significantly reduces the incidence of xerostomia and leads to recovery of saliva secretion and improvements in associated quality of life, and thus strongly supports a role for IMRT in squamous-cell carcinoma of the head and neck."