Delayed clinical complete response to intensity-modulated radiotherapy in nasopharyngeal carcinoma

Publication date: December 2017
Source:Oral Oncology, Volume 75
Author(s): Wen-Fei Li, Yuan Zhang, Xu Liu, Ling-Long Tang, Li Tian, Rui Guo, Li-Zhi Liu, Ying Sun, Jun Ma
ObjectiveTwelve 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 methodsMRI 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.ResultsOf 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).ConclusionsNearly 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.



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