Objective To evaluate the impact of the hypoxia induced by bevacizumab on the antitumor effect in combining with irradiation in CNI-H441 xenografts in mice. Methods Bevacizumab of 5 mg/kg mouse for groups of control, bevacizumab alone, irradiation alone, earlier combination (EC), and later combination (LC) were initially injected peritoneally. Single irradiation of 14 Gy (122Sc γ-ray) was given at the 4th hour for the group of irradiation alone, 24th hour for EC group, and 72nd hour for LC group after the initial injection. Tumor hypoxia, micro vessels density and permeability of tumor vasculature,pathological responses, apoptosis, and tumor growth delay curve were evaluated after using bevacizumab and/or irradiation. Results Although it was lower than the control at the 24 hr after using bevacizumab (3. 1 × 106: 6.1 × 106 ;t = - 1.73 ,P > 0. 05), the HIF-1α rapidly increased to 3 - 4 times and 2 - 3 times of the control at day 3 (7.4 × 106: 20. 4 × 106; t = 2. 36, P < 0. 05) and lasted until day 10, which was consistent with the changes of tumor function vessels count. The count of residual micro vessel density count in LC group was higher than that in groups of EC and irradiation at day 3 after irradiation (9. 33: 3. 17;t =- 2. 43, P < 0. 05). The apoptotic count of tumor cells was lower in LC group than that in EC group (23.33: 43.83; t= 2.54, P< 0.05, at day 3 after radiation). Tumor growth delay time of LC groupwas shorter than that of EC groups (10. 5 days vs. 23. 0 days , t = 2. 67 , P < 0. 05) . Conclusions Hypoxia level induced by bevacizumab decreases the antitumor effect in later combination of bevacizumab and irradiaion. It shows a time window that determines whether the combination of bevacizumab and irradiation will be benefit or diverse.

PURPOSE: The purpose of this study was to explore the dosimetric difference between simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) and three-dimensional conformal radiotherapy (3DCRT), and the clinical outcomes of anal squamous cell carcinoma (ASCC) chemoradiotherapy featuring SIB-IMRT. MATERIALS AND METHODS: This study included ten patients with ASCC who underwent chemoradiotherapy using SIB-IMRT with 5-fluorouracil and mitomycin C. SIB-IMRT delivered 54 Gy to each primary tumor plus metastatic lymph nodes and 45 Gy to regional lymph nodes, in 30 fractions. Four patients received additional boosts to the primary tumors and metastatic lymph nodes; the median total dose was 54 Gy (range, 54 to 60 Gy). We additionally created 3DCRT plans following the Radiation Therapy Oncology Group 9811 protocol to allow dosimetric comparisons with SIB-IMRT. Locoregional control, overall survival, and toxicity were calculated for the clinical outcome evaluation. RESULTS: Compared to 3DCRT, SIB-IMRT significantly reduced doses to the external genitalia, bladder, and intestine, delivering the doses to target and elective nodal region. At a median follow-up time of 46 months, 3-year locoregional control and overall survival rates were 88.9% and 100%, respectively. Acute toxicities were treated conservatively. All patients completed radiotherapy with brief interruptions (range, 0 to 2 days). No patient experienced ≥grade 3 late toxicity during the follow-up period. CONCLUSION: The dosimetric advantages of SIB-IMRT appeared to reduce the toxicity of chemoradiotherapy for ASCC achieving high locoregional control in the extended period.
Anus Neoplasms ; Carcinoma, Squamous Cell* ; Chemoradiotherapy ; Epithelial Cells* ; Fluorouracil ; Follow-Up Studies ; Genitalia ; Humans ; Intestines ; Lymph Nodes ; Mitomycin ; Radiotherapy ; Radiotherapy Planning, Computer-Assisted ; Radiotherapy, Conformal ; Radiotherapy, Intensity-Modulated* ; Survival Rate ; Treatment Outcome ; Urinary Bladder