The effect of induction chemotherapy on tumor volume changes in patients with locoregionally advanced nasopharyngeal carcinoma.

person Guang Han Hubei Cancer hospital, Department of Radiation Oncology, Wuhan, China info_outline Guang Han, Ying Li, Yuan Wu, Jianping Bi, Yanping Li, Dandan Zheng, Conghua Xie, Desheng Hu

Authors person Guang Han Hubei Cancer hospital, Department of Radiation Oncology, Wuhan, China info_outline Guang Han, Ying Li, Yuan Wu, Jianping Bi, Yanping Li, Dandan Zheng, Conghua Xie, Desheng Hu Organizations Hubei Cancer hospital, Department of Radiation Oncology, Wuhan, China, Hubei Cancer Hospital, Department of Radiation Oncology, Wuhan, China, Hubei cancer Hospital, Department of Radiation Oncology, Wuhan, China, Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, NE, Zhongnan Hospital of Wuhan University, Wuhan, China Abstract Disclosures Research Funding Other Background: The use of induction chemotherapy (IC) in locoregionally advanced nasopharyngeal carcinoma (NPC) for radiotherapy target volume reduction is increasing, however, the number of cycles is still varying. The purpose of this study was to observe changes in the gross tumor volumes of nasopharynx primary lesion (GTV_T), metastatic retropharyngeal lymph node (GTV_RP), and metastatic cervical lymph node (GTV_N) on longitudinal CT images during multi-cycle IC, and identify the optimal number of IC cycles. Methods: Eighteen patients with locoregionally advanced NPC received 3 cycles of platinum-based doublet IC. Each patient underwent an initial CT scan before the first cycle, followed by repeat CT (rCT) scans 14 days after each IC cycle. GTV_T, GTV_RP, and GTV_N were contoured on each CT. Wilcoxon signed-rank test was used for the comparing the longitudinal tumor volume changes. Results: The volume reductions of GTV_T, GTV_RP, and GTV_N following IC were found to have different magnitudes. Compared with GTV_T 0 (before IC), the volume changes of GTV_Tn (n = 1, 2, 3) after IC were -3.1±0.7 cm 3 , -7.0 ±1.9 cm 3 and -6.9 ±2.0 cm 3 , respectively, corresponding to relative reductions of 12.0%, 22.5%, and 20.1%, respectively. The GTV_T volume reduction was significant following the first two cycles of IC ( P < 0.05) but insignificant following the third cycle. Similarly, compared with GTV_RP 0 , the volume changes of GTV_RPn (n = 1, 2, 3) after IC were -1.4±0.4 cm 3 , -2.5±0.5 cm 3 and -2.4±0.5 cm 3 , respectively, corresponding to relative reductions of 26.0%, 44.1%, and 42.2%, respectively. Again, the volume significantly decreased following the first two IC cycles ( P < 0.05) but remained unchanged or even slightly increased after the third cycle. In contrast, compared with GTV_N 0 , the volume changes of GTV_Nn (n = 1, 2, 3) after IC were -7.3±1.7 cm 3 , -13.5±2.9 cm 3 and -17.2±3.4 cm 3 , respectively, corresponding to relative reductions of 25.3%, 43.2%, and 54.7%, respectively. For GTV_N, significant volume reduction ( P < 0.05) was observed following each of the three IC cycles. All patients experienced grade 1 or 2 adverse events. Conclusions: A two-cycle IC is recommended for patients with large GTV_T and GTV_RP volumes before radiotherapy. However, for patients with a large GTV_N volume, a 3-cycle IC before radiotherapy is recommended.