Purpose: Concurrent chemotherapy and radiotherapy (CCRT) are effective in treatment of locoregionally advanced nasopharyngeal carcinoma (NPC). However, the prognostic factors after CCRT have not been evaluated. We therefore attempt to evaluate factors that influence treatment outcomes following CCRT.
Methods and materials: Seventy-four (5 in stage III and 69 in stage IV) patients with locoregionally advanced NPC were treated with CCRT. Radiotherapy was delivered either at 2 Gray (Gy) per fraction per day up to 70 Gy or 1.2 Gy, 2 fractions per day, up to 74.4 Gy. Concurrent chemotherapy consisted of cisplatin and 5-fluorouracil. Cox proportional-hazards model was used to analyze the prognostic factors which included age, gender, pathologic type, T, N, lactate dehydrogenase (LDH), and infiltration of the clivus.
Results: The primary tumor control rate at 3 years was 96.7% (95% confidence interval [CI]: 92.5-100), distant metastasis-free survival 81.1% (95% CI: 70.6-91.6), disease-free survival 77.0% (95% CI: 65.3-88.7), and overall survival 79.8% (95% CI: 69.2-90.4) with a median follow-up interval of 29 months (range 15-74 months). Cox proportional-hazards model revealed that infiltration of the clivus and serum level of LDH before treatment were the most two important factors that predict distant metastases. Infiltration of the clivus and the serum LDH level greater than 410 U/L were strongly associated with distant metastasis-free survival (p = 0.0004 and p = 0.0002, respectively). When these two risk factors were considered together, no distant metastasis was observed in 40 patients with both intact clivus and LDH < or = 410 U/L. On the contrary, 13 of the remaining 34 patients with at least one risk factor developed distant metastasis (p = 0.0001).
Conclusion: Our study demonstrates that CCRT can improve the primary tumor control of 96.7% and disease-free survival of 77.0% at 3-year follow-up. Distant metastasis, however, is the major cause of failure. Infiltration of the clivus by the tumor and LDH greater than 410 U/L are the two independent and useful prognostic factors in patients with locoregionally advanced NPC who were treated with CCRT. Good- and poor-risk patients can be distinguished by virtue of their having both conditions.