Wen-Fei Li1, Yuan Zhang1, Xu Liu1, Ling-Long Tang1, Li Tian2, Rui Guo1, Li-Zhi Liu2, Ying Sun1, Jun Ma3. 1. Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, 651 Dongfeng Road East, Guangzhou 510060, Guangdong, People's Republic of China. 2. Imaging Diagnosis and Interventional Center, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, 651 Dongfeng Road East, Guangzhou 510060, Guangdong, People's Republic of China. 3. Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, 651 Dongfeng Road East, Guangzhou 510060, Guangdong, People's Republic of China. Electronic address: majun2@mail.sysu.edu.cn.
Abstract
OBJECTIVE: Twelve weeks after radiotherapy is the recommended time-point for assessing tumor response in nasopharyngeal carcinoma (NPC); however, regression after 12 weeks remains unclear. We explored NPC regression and the prognosis of patients with delayed clinical complete response (cCR). MATERIALS AND METHODS: MRI images of 556 NPC patients treated with intensity-modulated radiotherapy (IMRT) between 2009 and 2012 were retrospectively reviewed. Clinical tumor response was assessed at 3-4 (assessment 1) and 6-9 months (assessment 2) after IMRT, and survival rates were compared. RESULTS: Of the 556 patients, 463 (83.3%) had cCR at assessment 1 (early cCR). Of the 93 patients with partial response at assessment 1, 45 (48.4%) achieved cCR at assessment 2 (delayed cCR), and 48 did not have cCR at assessment 2 (non-cCR). Locoregional failure rate was lower in patients with a cCR than those without a cCR at assessment 1 (7.1% vs. 26.9%, P < .001) and assessment 2 (7.1% vs. 45.8%, P < .001). Multivariate analysis showed cCR was a favorable prognostic factor for locoregional failure-free survival (LRFFS), failure-free survival (FFS), and overall survival (OS). Early and delayed cCR groups had better 5-year LRFFS (92.6% vs. 93.3% vs. 54.2%), FFS (83.8% vs. 84.4% vs. 48.5%) and OS (92.1% vs. 90.6% vs. 65.4%) than the non-cCR group (all P < .001). CONCLUSIONS: Nearly half of the patients with partial response at 3-4 months achieve cCR by 6-9 months; delayed cCR is not a poor prognosticator. We suggest later assessment of cCR at 6-9 months after IMRT is acceptable in responding NPC.
OBJECTIVE: Twelve weeks after radiotherapy is the recommended time-point for assessing tumor response in nasopharyngeal carcinoma (NPC); however, regression after 12 weeks remains unclear. We explored NPC regression and the prognosis of patients with delayed clinical complete response (cCR). MATERIALS AND METHODS: MRI images of 556 NPC patients treated with intensity-modulated radiotherapy (IMRT) between 2009 and 2012 were retrospectively reviewed. Clinical tumor response was assessed at 3-4 (assessment 1) and 6-9 months (assessment 2) after IMRT, and survival rates were compared. RESULTS: Of the 556 patients, 463 (83.3%) had cCR at assessment 1 (early cCR). Of the 93 patients with partial response at assessment 1, 45 (48.4%) achieved cCR at assessment 2 (delayed cCR), and 48 did not have cCR at assessment 2 (non-cCR). Locoregional failure rate was lower in patients with a cCR than those without a cCR at assessment 1 (7.1% vs. 26.9%, P < .001) and assessment 2 (7.1% vs. 45.8%, P < .001). Multivariate analysis showed cCR was a favorable prognostic factor for locoregional failure-free survival (LRFFS), failure-free survival (FFS), and overall survival (OS). Early and delayed cCR groups had better 5-year LRFFS (92.6% vs. 93.3% vs. 54.2%), FFS (83.8% vs. 84.4% vs. 48.5%) and OS (92.1% vs. 90.6% vs. 65.4%) than the non-cCR group (all P < .001). CONCLUSIONS: Nearly half of the patients with partial response at 3-4 months achieve cCR by 6-9 months; delayed cCR is not a poor prognosticator. We suggest later assessment of cCR at 6-9 months after IMRT is acceptable in responding NPC.