Factors influencing the parotid function in nasopharyngeal carcinoma treated with parotid-sparing radiotherapy.

BACKGROUND: To evaluate the factors influencing post-irradiation parotid gland function in nasopharyngeal cancer treated with parotid-sparing radiotherapy. METHODS: This study consisted of 45 patients with nasopharyngeal cancer treated with radiotherapy including 3D conformal radiotherapy, intensity-modulated radiotherapy and high-dose-rate brachytherapy. The mean follow-up time was 37.5 months (range: 15-50 months). Objective parotid gland function was assessed by series sialoscintigraphy pre-irradiation and post-irradiation at 1, 6, 12 and 18 months. Subjective salivary function was recorded by the LENT/SOMA system. Wilcoxon signed-rank test was used to compare the secretion ratio (SR) of parotid gland before and after treatment. Mann-Whitney rank-sum test was used to determine the factors influencing the post-irradiated SR. Chi-square test was used to compare the correlation between subjective grading of xerostomia and objective grading of parotid glands. RESULTS: There was a significant difference between the pre-irradiation and post-irradiation parotid gland's SR at 1 (0.30 versus 0.01, P < 0.05) and 6 months (0.03 versus 0.08, P < 0.05). However, there was no significant difference compared with the pre-irradiation SR at 12 (0.30 versus 0.20, P > 0.05) and 18 months (0.30 versus 0.18, P > 0.05). There was significant correlation between subjective and objective salivary function (P = 0.024) at 12 months after radiotherapy. The factor that impacted the preservation of parotid function was mean dose to the parotid gland >38.0 Gy (P < 0.05). CONCLUSIONS: Our results demonstrated that parotid function could recover 1 year after treatment with parotid-sparing radiotherapy in patients with nasopharyngeal cancer. The most important factor that influenced parotid function was the mean dose to the parotid gland.

High-dose-rate stereotactic brachytherapy for patients with newly diagnosed glioblastoma multiformes.

PURPOSE: To evaluate high-dose-rate (HDR) stereotactic brachytherapy (STBT) for glioblastoma multiforme (GBM). MATERIALS AND METHODS: Between August 1994 and December 1998, 28 patients with newly diagnosed GBM underwent surgery, external-beam radiotherapy (EBRT) and HDR STBT. STBT eligibility criteria included unifocal lesions, residual tumor < or = 6 cm in maximum diameter, supratentorial lesions, tumors not crossing the midline, tumors without subependymal spread and Karnofsky performance status (KPS) > 60. STBT was delivered over five consecutive days with two fractions per day for a total median dose of 30 Gy. Twenty-eight STBT eligible GBM patients treated with surgery and EBRT only over the same period were matched controls. RESULTS: Median survival times for the STBT group and controls were 19.5 versus 12.5 months; one and two year survival rates were 89% versus 42% and 61% versus 28%, respectively (p = 0.12). Using multivariate analysis, age, KPS and HDR STBT were significant factors predicting survival. By RPA class, 2-year survival rates for STBT and controls were: III--78% versus 50%; IV--40% versus 0%; V--21% versus 15%, respectively. Corresponding median survival times in months were: 41.6 versus 21.2 (p = 0.39); 16.7 versus 12.1 (p = 0.36); 18.7 versus 10.6 (p = 0.02). No major complications were found in the STBT arm. CONCLUSIONS: Because of small patient numbers, median survival time increases were only statistically significant in the RPA Class V patients, but a strong survival time trend emerged favoring patients undergoing HDR STBT. Further prospective study is warranted to fully assess the merits of this technique for GBM management.