Objective To investigate the relationship of radiation dose with the volume and late toxicity of the sternocleidomastoid muscle ( SM) in patients with nasopharyngeal carcinoma. Methods SM was divided into upper part and lower part based on the lower edge of cricoid cartilage. Patients were divided into three groups according to the prescribed dose for clinical target volume at the lower neck ( CTV2 ) ( 0, 54,60 Gy) . The dosimetric parameters included Dmean , V66 , and V60 for the upper, lower, and whole SM. SM was delineated and the volume was calculated on computed tomography images in the treatment planning system before and at 6, 12, and 18 months after treatment. The anteroposterior and transversal diameters of SM at C3?C4 , C4?C5 , C5?C6 , and C6?C7 levels were measured and recorded. Late toxicity of neck skin and SM was evaluated according to the Common Terminology Criteria for Adverse Events V4 .0 criteria. Between?group comparison was made by t?test or Kruskal?Wallis non?parametric test. Between?group comparison of the sample rate was made by one?way analysis of variance. The correlation analysis was made by Spearman correlation. Results There were significant difference in SM volume between the three time points after treatment ( P=0. 000) . At 12 or 18 months after treatment, the volume of SM wasignificantly reduced ( P=0. 000,0. 000);the reduction in SM volume was significantly correlated with V66 of the SM and the upper SM ( P=0. 015,0. 020) . At 18 months after treatment, SM fibrosis was significantly correlated with V60 of the upper SM ( P=0. 030);the fibrosis of neck skin was significantly correlated with the Dmean and V60 of the upper SM ( P=0. 029,0. 005) . Conclusions In order to prevent the incidence of the fibrosis of neck skin and SM, the dose homogeneity should be as high as possible, while the number of hot spots should be as small as possible.

Objective To analyze the prognostic factors in patients with initially diagnosed bone-only metastatic nasopharyngeal carcinoma (NPC). Methods We collected the data of 68 patients with initially diagnosed bone-only metastatic NPC admitted to The Affiliated Tumor Hospital of Shantou University Medical College from 1997 to 2015. Forty-nine patients received chemoradiotherapy. The Kaplan-Meier method was used to calculate the overall survival rate;the log-rank test was used for univariate prognostic analysis;the Cox model was used for multivariate prognostic analysis. Results The median follow-up was 953 months. The 1-, 2-, 3-, and 5-year overall survival ( OS) rates were 53%, 38%, 21%, and 15%, respectively. The median OS time was 134 months. The univariate prognostic analysis showed that spinal metastases, the number of bone metastases, lactic dehydrogenase level before treatment, the radiotherapy technology and dose for primary tumor, and the short-term outcome of primary tumor were associated with OS ( P=002, 001, 000, 002, 002, 001 ) . The multivariate prognostic analysis showed that ≤3 bone metastases, dose to primary tumor>65 Gy, and intensity-modulated radiotherapy ( IMRT) were favorable prognostic factors for OS ( P=003,002,004) . Conclusions For patients with initially diagnosed bone-only metastatic NPC, active treatment ( IMRT, dose to primary tumor>65 Gy) should be considered for those with ≤3 bone metastases to achieve a complete response of primary tumor.