The strategy and feasibility of dose optimization in clinical target volume Ⅱb in patients with N0‐N1 nasopharyngeal carcinoma
Huang Wenxuan1, Zong Dan1, Zhang Bin1, Wang Lijun1, Zhang Lanfan2, Ma Chengxian1, Yin Li1, Huang Shengfu1, He Xia1
1Department of Radiation Oncology, Affiliated Cancer Hospital of Nanjing Medical University & Jiangsu Cancer Hospital & Jiangsu Institute of Cancer Research, Nanjing 210009, China; 2Department of Medical Imaging, Jiangsu Cancer Hospital, Nanjing 210009, China
Abstract：Objective To determine the safety of prophylactic irradiation dose CTV60Gy optimized to CTV50Gy for IIb region in patients with stage N0‐N1 nasopharyngeal carcinoma (NPC) and the dose advantage and clinical value for parotid gland protection, and to understand the diagnostic value of PET‐CT and diffusion‐weighted imaging (DWI) for suspicious positive lymph nodes in the neck (5 mm≤maximum short diameter<10 mm). Methods Clinical data of 157 patients with primary non‐metastatic NPC (N0‐N1) admitted to our hospital from June 2015 to March 2017 were retrospectively analyzed. 104 patients underwent IIb clinical target volume optimization guided by multimodal imaging system. Survival analysis was performed by Kaplan ‐ Meier method. Univariate/multivariate regression analysis was performed to analyze the pattern of cervical lymph node recurrence. Paired t‐test was used to compare the differences in target volume and parotid gland dose parameters before and after dose optimization. Results Sixty patients underwent single‐neck optimization in stage N1, 25 patients received double‐neck optimization (only those with retropharyngeal lymph node metastasis), and 19 patients underwent double‐neck optimization in stage N0. Three patients had cervical regional recurrence, all in‐field. The 5‐year overall survival rate was 93.3%. The lymph node recurrence‐free survival rate, local recurrence‐free survival rate, distant metastasis‐free survival rate and disease‐free survival rate were 97.1%, 91.3%, 88.5% and 80.8%, respectively. Cervical lymph node recurrence was associated with local recurrence in the nasopharynx, regardless of retropharyngeal lymph node status. Fourteen patients had suspicious positive cervical lymph nodes in IIb region, with a mean maximum short diameter of 7.1 (5~9) mm on the largest cross‐sectional plane, and 11 of them were positive on PET‐CT, with a mean SUVmax of 2.96 (2.5~3.3). There was no significant difference in GTV after optimization (P>0.05). Dmean, Dmax, D50% and V26Gy of parotid gland were significantly lower than those of conventional plan (all P<0.01). Conclusions It is safe to optimize CTV60Gy to CTV50Gy in IIb region in patients with N0‐N1 NPC, and the exposure dose to normal tissues around the parotid gland and neck is significantly reduced. For small lymph nodes that do not meet the diagnostic criteria, it needs to be individualized in combination with multimodality imaging systems, such as PET‐CT and DWI.
Huang Wenxuan,Zong Dan,Zhang Bin et al. The strategy and feasibility of dose optimization in clinical target volume Ⅱb in patients with N0‐N1 nasopharyngeal carcinoma[J]. Chinese Journal of Radiation Oncology, 2022, 31(9): 778-784.
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