title: [The constrastive analysis on distant metastasis before and after radiotherapy of nasopharyngeal carcinoma].
abstract: OBJECTIVE
  To explore the duration related to distant metastases of nasopharyngeal carcinoma (NPC).
  
  
  METHODS
  One hundred and three cases with confirmative diagnosis of NPC, in which the distant metastasis had happened before radiotherapy, were called the natural metastasis group. Another one hundred and thirty-eight cases, in which the distant metastasis had happened after radiotherapy, were called the metastasis after radiotherapy group. The clinical data and appearance time on distant metastasis from the two groups were analyzed.
  
  
  RESULTS
  It took 10.78 months (95% CI: 8.68-12.88) on average in the natural metastasis group from the primary symptom to the distant metastasis, and 20.77 months on average in the metastasis after radiotherapy group. Comparing the two groups, there was highly remarkable difference (P < 0.01). The distant metastasis happened in 91.26% of the cases in the natural metastasis group in 2 years. And in 1 year and in 2 years, the distal metastasis incidences of the natural metastasis group was higher than those of the metastasis after radiotherapy group by 34.41% and 28.94%, respectively. The distant metastasis happened in all cases in the natural metastasis group in 5 years, while in 2.9% of the cases in the metastasis after radiotherapy group beyond 5 years. There wasn't any obvious difference in the patients' sex and the appearance rate of the primary symptom (P > 0.05). But in the metastasis after radiotherapy group, the patients were younger and the T and N stages were earlier.
  
  
  CONCLUSIONS
  The distal metastasis in the metastasis after radiotherapy group was at least 1-2 years later than that in the natural metastasis group. It was perhaps relative to the younger patients and the earlier stages.
authors.affiliation: Department of Head and Neck Surgery, Affiliated Cancer Hospital, Guangxi Medical University, Nanning ,530021, China. moligen@gxmu.net.cn
authors.forename: Ligen
authors.initials: L
authors.lastname: Mo
authors.forename: Guoqian
authors.initials: G
authors.lastname: Kuang
authors.forename: Rongning
authors.initials: R
authors.lastname: Yang
authors.forename: Long
authors.initials: L
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D009362:Neoplasm Metastasis; D055815:Young Adult