Familial Nasopharyngeal Carcinoma 6

Prognostic Factors in Nasopharyngeal Cancer 127Multivariate analysisLFFS MFS DFS OS LFFS MFS DFSp = 0.0001p = 0.0001––––––––––––––––––––––––––––––––p < 0.0001p < 0.0001p = 0.8555p = 0.0001p = 0.0001p = 0.0001n.s.p = 0.0001p = 0.0001p = 0.0001––n.s.n.s.p = 0.7107p = 0.0006p = 0.0001p = 0.0001––p < 0.0001p = 0.0001p = 0.014p = 0.004p = 0.002n.s.––p = 0.0001p = 0.0021––n.s.p < 0.0001n.s.p = 0.001n.s.p = 0.023– – – – – p = 0.0004 –––p = 0.0001p = 0.0001––––p = 0.008p < 0.001p < 0.001 a p < 0.001 p < 0.001 p = 0.10 p < 0.001 a p < 0.001 p < 0.001– – – p = 0.0385 – – –n.s.n.s.Of note, all studies mentioned earlier used conventionaltechnique. Thus, whether altered fractionatedschedule could be a treatment-related prognosticfactor for NPC is largely unknown in the modern eraof conformal radiation therapy or IMRT.Tumor regression at the primary site and theinvolved cervical lymph nodes are usually observedduring the radiation course. It is intuitive to postulatethe extent of tumor regression during irradiation asproportional to the radiosensitivity, and outcomeafter the completion of radiation may be favorablyassociated with more substantial tumor volumeregression during treatment. However, the resultsfrom the experience of 101 patients with locoregionallyadvanced NPC indicated otherwise: No statisticallysignificant differences for local/regional controlor overall survival rates could be found amongpatients with slow, moderate, or rapid response to45 Gy of radiation therapy at the primary or nodaldisease (Fang et al. 2001). Furthermore, T-classificationwas the only significant prognostic factor for locoregionalcontrol after multivariate analysis.Bony destruction of the skull base is frequentlyseen in NPC and believed to be a significant prognosticfactor as discussed in an earlier section. Theimplication of bony regeneration after radiationtherapy on local control was rarely investigated. Fanget al. (1999) retrospectively reviewed 90 patients withskull-base destruction on CT scan. Bony regenerationin postradiation CT scan was noted in 57 patients.The 3-year rates of local control were 77% vs. 21% forpatients with or without bony regeneration (p