Delayed clinical complete response to intensity-modulated radiotherapy in nasopharyngeal carcinoma. (December 2017)

• Record Type: Journal Article
• Authors: Li, Wen-Fei; Zhang, Yuan; Liu, Xu; Tang, Ling-Long; Tian, Li; Guo, Rui; Liu, Li-Zhi; Sun, Ying; Ma, Jun
• Is Part Of: Oral oncology. Volume 75(2017)
• Page Start: 120
• Page End: 126
• Publication Date: 2017-12
• Subjects: Nasopharyngeal carcinoma -- Clinical complete response -- Prognosis -- Intensity-modulated radiotherapy; Mouth -- Cancer -- Periodicals; Mouth -- Tumors -- Periodicals; Mouth Diseases -- Periodicals; Mouth Neoplasms -- Periodicals; Bouche -- Cancer -- Périodiques; Bouche -- Tumeurs -- Périodiques; Tumeurs -- Périodiques; Electronic journals; 616.9943105
• DOI: 10.1016/j.oraloncology.2017.10.020
• Languages: English
• ISSNs: 1368-8375

Abstract

Highlights: The pattern of tumor regression after IMRT in patients with NPC was investigated. Many patients with partial response at 3–4 months after IMRT achieved cCR by 6–9 months. Delayed cCR at 6–9 months after IMRT was not a poor prognostic factor. Later assessment of cCR at 6–9 months after IMRT is acceptable in responding NPC. 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.