RESUMO
PURPOSE/OBJECTIVES: NRG/RTOG 0436 evaluated cetuximab added to chemoradiation (CRT) for non-operative esophageal cancer management. PRO objectives assessed improvement in the FACT-Esophageal cancer subscale (ECS), version 4, with cetuximab, and if improved ECS correlated with clinical complete response (cCR). MATERIALS/METHODS: Patients were randomized to cisplatin/paclitaxel/radiation ± cetuximab. Overall survival (OS) was the primary endpoint, with a 420 patient target, which also provided 82% power to detect ≥ 15 increase in the proportion of cetuximab patients with ECS improvement from baseline to 6-8 weeks post-CRT; α = 0.05, using a χ2 test. Improvement in ECS and its Swallowing and Eating Indices (SI, EI) was defined as 5, 4 and 2 point increases, respectively, from baseline to 6-8 weeks post-CRT. Univariate logistic regression assessed if cCR was associated with improved ECS. RESULTS: This study was stopped early for not meeting a pre-specified OS endpoint and did not show survival benefit. Of 420 planned patients, 344 enrolled and 281 consented to PROs. ECS was completed by 261 (93%) at baseline, 173 (66%) 6-8 weeks post-CRT, and 117 (64%) at 1 year. At 6-8 weeks, patients receiving CRT + Cetuximab didn't have improved ECS; they experienced a lower proportion of improvement compared to standard CRT (37% vs. 53%; P = 0.04). The proportion of CRT patients with improvement in SI was 9% higher than with cetuximab, but not statistically significant (39% vs. 30%, P = 0.22). There was no association between treatment and EI. When examining ECS scores at 1 year by cCR vs. residual disease, a higher proportion of cCR patients improved, but not statistically significant (48% vs. 45%, P = 0.74). CONCLUSIONS: The addition of cetuximab to CRT for the nonoperative management of esophageal cancer did not improve PROs.
RESUMO
BACKGROUND: Pencil beam scanning (PBS) proton therapy for moving targets is known to be impacted by interplay effects between the scanning beam and organ motion. While respiratory motion in the thoracic region is the major cause for organ motion, interplay effects depend on the delivery characteristics of proton accelerators. PURPOSE: To evaluate the impact of different types of PBS proton accelerators and spot sizes on interplay effects, mitigations, and plan quality for Stereotactic Body Radiation Therapy (SBRT) treatment of non-small cell lung cancer (NSCLC). METHODS: Twenty NSCLC patients treated with photon SBRT were selected to represent varying tumor volumes and respiratory motion amplitudes (median: 0.6 cm with abdominal compression) for this retrospective study. For each patient, plans were created using: (1) cyclotron-generated proton beams (CPB) with spot sizes of σ = 2.7-7.0 mm; (2) linear accelerator proton beams (LPB) (σ = 2.9-5.5 mm); and (3) linear accelerator proton minibeams (LPMB) (σ = 0.9-3.9 mm). The energy switching time is one second for CPB, and 0.005 s for LPMB and LPB. Plans were robustly optimized on the gross tumor volume (GTV) using each individual phase of four-dimensional computed tomography (4DCT) scans. Initially, single-field optimization (SFO) plans were evaluated; if the plan quality did not meet the dosimetric requirement, multi-field optimization (MFO) was used. MFO plans were created for all patients for comparisons. For each patient, all plans were normalized to have the same dose received by 99% of the GTV. Interplay effects were evaluated by computing the dose on 10 breathing phases, based on the spot distribution. Volumetric repainting (VR) was performed 2-6 times for each plan. We compared volume receiving 100% of the prescribed dose (V100%RX) of the GTV, and normal lung V20Gy. RESULTS: Twelve of 20 plans can be optimized sufficiently with SFO. SFO plans were less sensitive to the interplay effect compared to MFO plans in terms of target coverage for both LPB and LPMB. The following comparisons showed results utilizing the MFO technique. In the interplay evaluation without repainting, the mean V100%RX of the GTV were 99.42 ± 0.6%, 97.52 ± 3.9%, and 94.49 ± 7.3% for CPB, LPB, and LPMB plans, respectively. Following VR (2 × for CPB; 3 × for LPB; 5 × for LPMB), V100%RX of the GTV were improved (on average) by 0.13%, 1.84%, and 4.63%, respectively, achieving the acceptance criteria of V100%RX > 95%. Because of fast energy switch in linear accelerator proton machines, the delivery time for VR plans was the lowest for LPB plans, while delivery time for LPMB was on average 1 min longer than CPB plans. The advantage of small spot machines was better sparing in normal lung V20Gy, even when VR was applied. CONCLUSION: In the absence of repainting, proton machines with large spot sizes generated more robust plans against interplay effects. The number of VR increased with decreasing spot sizes to achieve the acceptance criteria. VR improved the plan robustness against interplay effects for modalities with small spot sizes and fast energy changes, preserving the low dose sparing aspect of the LPMB, even when motion is included.