title: Reducing xerostomia after chemo-IMRT for head-and-neck cancer: beyond sparing the parotid glands.
abstract: OBJECTIVE
  To assess whether, in addition to sparing the parotid glands (PGs), xerostomia after chemotherapy plus intensity-modulated radiotherapy (chemo-IMRT) for head-and-neck cancer is affected by reducing the dose to the other salivary glands.
  
  
  METHODS
  In a prospective study, 78 patients with Stage III-IV oropharynx/nasopharynx cancer underwent chemo-IMRT, with the aim of sparing the parts of the bilateral PGs, oral cavity (OC) containing the minor salivary glands, and contralateral submandibular gland (SMG) outside the target (when contralateral level I was not a target). Before therapy and periodically for 24 months, validated patient-reported xerostomia questionnaire (XQ) scores and observer-graded xerostomia scores were recorded. Also, the stimulated and unstimulated saliva was measured selectively from each of the PGs and SMGs. The mean OC doses served as surrogates of minor salivary gland dysfunction. Regression models assessed the XQ and observer-graded xerostomia predictors.
  
  
  RESULTS
  Statistically significant predictors of the XQ score on univariate analysis included the OC, PG, and SMG mean doses and the baseline XQ score, time since RT, and both stimulated and unstimulated PG saliva flow rates. Similar factors were statistically significant predictors of observer-graded xerostomia. The OC, PG, and SMG mean doses were moderately intercorrelated (r = 0.47-0.55). On multivariate analyses, after adjusting for the PG and SMG doses, the OC mean dose (p < .0001), interval from RT (p < .0001), and stimulated PG saliva (p < .0025) were significant predictors of the XQ scores and the OC mean dose and time for observer-graded xerostomia. Although scatter plots showed no thresholds, an OC mean dose of <40 Gy and contralateral SMG mean dose of <50 Gy were each associated with low patient-reported and observer-rated xerostomia at almost all post-therapy points.
  
  
  CONCLUSIONS
  The PG, SMG, and OC mean doses were significant predictors of both patient-reported and observer-rated xerostomia after chemo-IMRT, with OC doses remaining significant after adjusting for the PG and SMG doses. These results support efforts to spare all the salivary glands by IMRT, beyond the PGs alone.
authors: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, USA. eisbruch@umich.edu
authors: Michael
authors: M
authors: Little
authors: Matthew
authors: M
authors: Schipper
authors: Felix Y
authors: FY
authors: Feng
authors: Karen
authors: K
authors: Vineberg
authors: Craig
authors: C
authors: Cornwall
authors: Carol-Anne
authors: CA
authors: Murdoch-Kinch
authors: Avraham
authors: A
authors: Eisbruch
mesh_terms: D000704:Analysis of Variance; D059248:Chemoradiotherapy / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D009303:Nasopharyngeal Neoplasms / Q000628:therapy*; D015588:Observer Variation; D059351:Organ Sparing Treatments / Q000009:adverse effects / Q000379:methods*; D009959:Oropharyngeal Neoplasms / Q000628:therapy*; D010306:Parotid Gland / Q000528:radiation effects; D011446:Prospective Studies; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods*; D012463:Saliva / Q000378:metabolism; D012469:Salivary Glands / Q000378:metabolism / Q000528:radiation effects*; D012470:Salivary Glands, Minor / Q000378:metabolism / Q000528:radiation effects; D011795:Surveys and Questionnaires; D014987:Xerostomia / Q000517:prevention & control*