Optimizing induction chemotherapy regimens for radiotherapy in patients with locoregionally advanced nasopharyngeal carcinoma

Abstract

Background and Purpose The optimal number of cycles of induction chemotherapy (IC) in locoregionally advanced nasopharyngeal carcinoma (LANPC) remains unresolved. This study aimed to quantitatively assess the changes in gross tumor volumes (GTVs) and to select the most optimal number of IC cycles. Methods We analyzed 54 patients who received a three‐cycle IC before commencing radiotherapy, with the tumor and nodal responses assessed by a CT scan before IC and after each IC cycle. The gross tumor volumes of the nasopharynx primary lesion (GTV_T), involved retropharyngeal lymph node (GTV_RP), and involved cervical lymph node (GTV_N) were contoured on each scan. The volume change following each IC cycle was evaluated with Wilcoxon signed‐rank test. The three‐dimensional vector displacements of target centers were also calculated and compared. Results The volume reductions of GTVs following IC varied across different patients and showed different trends for the three GTV types. GTV_T and GTV_RP did not display further volume reduction after two IC cycles, whereas GTV_N showed monotonic volume decreases. For GTV_T and GTV_RP following the three IC cycles, the total volume reduction relative to the initial volume before IC was 12.0%, 22.5%, and 20.1% and 26.0%, 44.1%, and 42.2%, respectively. In contrast, for GTV_N, continuing volume reduction was observed with a total reduction of 25.3%, 43.2%, and 54.7% following the three cycles, and the reductions were all significant. Average displacements of the GTVs were <1.5 mm in all directions; their average three‐dimensional displacements were 2.6, 4.0, and 1.7 mm, respectively. Acceptable toxicity was observed in most patients. Conclusion This study supports two cycles of IC before radiotherapy for patients with LANPC if the initial metastatic cervical lymph node volume is not dominating. Otherwise, three cycles of IC is recommended to further reduce the cervical node volume.

The optimum number of induction chemotherapy cycles for N3M0 stage nasopharyngeal carcinoma based on pre-treatment plasma EBV DNA

“…Besides, it's commonly not recommended for the elderly and those with poor medical conditions. Given these concerns, more and more studies are trying to develop personalized ICC for patients with different stage and risk strati cation so that the AEs caused by chemotherapy could be minimized under the condition of obtaining the similar clinical bene ts [17,[29][30][31].…”

Effects of concurrent chemoradiotherapy with or without Endostar on the regression of retropharyngeal lymph node and prognosis of patients with locally advanced nasopharyngeal carcinoma: a retrospective study

“…The RLNs volume before and after radiotherapy is defined as RNV before and RNV after , respectively. The RNVs regression rate = (RNV before -RNV after ) /RNV before * 100% (Lee et al 2016 ; Li et al 2023 ). The median regression rate of RLNs was taken as the cut-off value, and the patients were divided into high regression rate (HRR) and low regression rate (LRR).…”

Embracing Personalized Strategies in Radiotherapy for Nasopharyngeal Carcinoma: Beyond the Conventional Bounds of Fields and Borders

“…Furthermore, the reduction in volume of the primary tumor appeared to level off after two cycles of IC, whereas that of the affected LNs continued to decrease after the third cycle. A retrospective study documented volume reductions of 12.0%, 23%, and 20% in the NP tumor, 26%, 44%, and 42% in the RP LN, and 25%, 43%, and 55% in the cervical LN, following each successive cycle of IC [74].…”