Evaluation of Esomeprazole in Treating Gastro-esophageal Reflux Disease (GERD) in Head and Neck Cancer Patients Exposed to Radiation Therapy

The annual incidence of squamous cell carcinoma of the head and neck (SCCHN) is 40,000 cases per year in the US and 60,000 cases per year in Europe. Radiation therapy is employed in combination with chemotherapy in primary treatment or as adjuvant therapy for over half of patients with SSCHN.

A high incidence of pathologic laryngopharyngeal reflux and gastroesophageal reflux is observed in patients with head and neck cancer. When treatment for the cancer includes radiation therapy, an incidence of 90% has been reported [2]. Although the interplay between acid reflux and the development of head and neck cancer remains unclear, there is a strong argument that radiation therapy worsens the problem by muting the body's ability to neutralize acid.

Radiation therapy is extensively used in the treatment of squamous cell carcinoma of the head and neck. Radiation therapy works by exploiting a survival differential between malignant cells and normal cells. Simply stated, the malignant cells are more likely to die with radiation when compared to normal non-malignant cells. However, not all normal cells respond equally and some normal tissues have marked sensitivity to radiation damage. Salivary glands are one such radiosensitive tissue that is permanently destroyed with external-beam radiotherapy.

Damage to salivary tissues by radiation decreases their ability to excrete saliva. This is supported by Olmos et al, who used salivary scintigraphy on both irradiated and non-irradiated patients and found that 84% of those irradiated had total or partial disturbance in both baseline and stimulated function. Of those treated with greater than 4500cGy, salivary excretion was almost invariably impaired. Xerostomia is the term for the dry mouth, which can result from this loss.

In addition to the volume of the saliva, the contents of the saliva are also important. Helm et al. "…evaluated the properties of human saliva relevant to its potential contribution to esophageal acid clearance." By measuring the capacity for acid neutralization and plotting titration curves, they identified that saliva and especially its bicarbonate content play an important role in neutralization of esophageal acid in both resting and lozenge-stimulated states.

As saliva plays an active role in the neutralization of esophageal acid and its clearance from the esophagus, loss of saliva is predicted to increase the severity and incidence of reflux as the protective effect of saliva's ability to clear and neutralize acid reflux is diminished. Korsten et al., assessed the effects of chronic xerostomia on parameters of gastroesophageal reflux and esophagitis and reported markedly impaired clearance of acid from the esophagus and abnormal 24-hour intra-esophageal pH studies from a cohort of male patients with xerostomia.

Medications are available to increase salivary flow but these are often minimally effective and poorly tolerated. Decreasing stomach acid production is an alternative method of mitigating the effect of GERD in these patients.

Esomeprazole has been proven beneficial in the treatment of gastroesophageal reflux disease and is anticipated to be beneficial in treating SCCHN patients treated with external-beam radiation therapy.