Salivary flow rate after conventional and intensity-modulated radiation therapy

Conventional 3-dimensional conformal radiation therapy (3DCRT) for head and neck cancer (HNC) can cause hyposalivation, leading to caries and tooth extraction-related osteoradionecrosis. Intensity-modulated radiation therapy (IMRT) delivers more focused radiation than does 3DCRT. To reduce hyposalivation, the Quantitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC) guidelines limit salivary gland radiation dose. In this study, the authors compared the salivary flow rate in patients receiving 3DCRT and those receiving IMRT and evaluated the effect of their treatment satisfying the QUANTEC guidelines on hyposalivation.

The authors evaluated findings in 96 patients with HNC who received radiation therapy (RT); 20 received unilateral 3DCRT, 17 received bilateral 3DCRT, and 59 received IMRT. The authors measured stimulated whole saliva before radiation and 3 and 12 months after radiation. The authors defined hyposalivation as stimulated whole saliva less than 3.5 grams per 5 minutes.

At 12 months, 50% and 54% of patients receiving unilateral 3DCRT and IMRT, respectively, exhibited nonstatistically significant hyposalivation compared with 71% of patients receiving bilateral 3DCRT (P = .2). A lower proportion of patients receiving IMRT (27%) and unilateral 3DCRT (5%) had decreased salivary flow (< 25% of baseline) than did those receiving bilateral 3DCRT (59%; P < .004); fewer patients whose treatment satisfied the QUANTEC guidelines exhibited hyposalivation than patients whose treatment did not fullfill QUANTEC guidelines (39% versus 71%; P < .002).

Twelve months after RT for HNC, treatment satisfying the QUANTEC guidelines resulted in decreased hyposalivation. Unilateral 3DCRT and IMRT may result in less hyposalivation than does bilateral 3DCRT.

Patients with HNC treated with modern RT techniques have a lower risk of developing hyposalivation, particularly if the QUANTEC guidelines are met, which also may result in decreased dental caries, tooth extractions, and postextraction osteoradionecrosis. Management of HNC requires a multidisciplinary team, including dentists and radiation oncologists.