The effects of radiation therapy on salivary function in patients with head and neck cancer

Eighty nasopharyngeal carcinoma (NPC) patients and another eighty head and neck cancer (HNC, non-NPC) patients were enrolled as two experimental groups to study their salivary function by using Tc99m sialography. Twenty healthy subjects were also employed as a control group. The patients received an intravenous injection of 4 mCi of 99mTc-pertechnetate (Tc-99mO4-). The data were collected at a rate of 1 frame per 15 seconds for the total time of 30 minutes, and the patients received stimulations for salivary secretion by ingesting 0.5cc of lemon juice 15 min after the start of data acquisition. The salivary function was measured on Pre-RT (radiation therapy), During-RT and Post-RT periods. The results showed no statistical significance for maximum uptake (%) and excretion rate (%) between Control and Pre-RT group on parotid or submandibular glands function. This was the same in the age groups (age below 40 and age above 40) and sex groups. The NPC group had a decreasing maximum uptake (%) 3 months after RT on both parotid glands and submandibular glands, whereas the HNC group showed no obvious difference. The excretion rate (%) of both parotid and submandibular glands reached its lowest mark after 3-6 months in both the NPC and HNC groups and then started to recover progressively. For NPC patients, the radiation damage to the parotid glands was greater than to the submandibular glands, whereas the effect was reversed on HNC patients. It is important that the radiation therapist should preserve salivary function whenever possible.