Enrollment of Elderly Patients With Locally Advanced Non–Small Cell Lung Cancer in Multi-institutional Trials of Proton Beam Radiation Therapy

Advances and Challenges in Conducting Clinical Trials With Proton Beam Therapy

Advances in proton therapy have garnered much attention and speculation in recent years as the indications for proton therapy have grown beyond pediatric, prostate, spine, and ocular tumors. To achieve and maintain consistent access to this cancer treatment and to ensure the future viability and availability of proton centers in the United States, a call for evidence has been heard and answered by proton radiation oncologists. Answers provided in this review include the evolution of proton therapy research, rationale for proton clinical trial design, challenges in and barriers to the conduct of proton therapy research, and other unique considerations for the study of proton therapy.

Chemoradiation with Hypofractionated Proton Therapy in Stage II-III Non-Small Cell Lung Cancer: A YYY Phase 1/2 Trial

INTRODUCTION

Hypofractionated radiotherapy has been safely implemented into the treatment of early-stage non-small cell lung cancer (NSCLC), but not locally advanced (LA-) NSCLC due to prohibitive toxicities with photon therapy. Proton therapy, however, may allow for safe delivery of hypofractionated radiotherapy. We sought to determine whether hypofractionated proton therapy with concurrent chemotherapy improves overall survival.

METHODS & MATERIALS

The YYY conducted a phase 1/2 single-arm nonrandomized prospective multicenter trial from 2013 through 2018. Thirty-two patients were consented; 28 were eligible for on-study treatment. Patients had AJCCv7 stage II or III unresectable NSCLC and received hypofractionated proton therapy at 2.5-4 Gy per fraction to a total 60 Gy with concurrent platin-based doublet chemotherapy. The primary outcome was 1-year overall survival comparable to that reported for RTOG 9410 of 62%.

RESULTS

The trial closed early due to slow accrual, in part, from a competing trial, NRG 1308. Median patient age was 70 (range, 50-86) years. Patients were predominantly male (N=20), white (N=23), and prior smokers (N=27). Most had stage III NSCLC (N=22), 50% of whom had adenocarcinoma. After a median follow-up of 31 months, the 1- and 3-year overall survival rates were 89% and 49%, and progression-free survival rates were 58% and 32%, respectively. No acute grade 3 or higher esophagitis occurred. Only 14% developed a grade 3 or higher radiation-related pulmonary toxicity.

CONCLUSION

Hypofractionated proton therapy delivered at 2.5-3.53 Gy per fraction to a total 60 Gy with concurrent chemotherapy provides promising survival and additional examination through larger studies may be warranted.

Proton therapy for non-small cell lung cancer: the road ahead

Proton therapy is an evolving radiotherapy modality with indication for numerous cancer types. With the benefits of reducing dose and sparing normal tissue, protons offer a clear physical and dosimetric advantage over photon radiotherapy for many patients. However, its impact on one type of disease, non-small cell lung cancer (NSCLC), is still not fully understood. Our review aims to highlight the data for using proton therapy in NSCLC, with a focus on the clinical data-or lack thereof-supporting proton treatment for early and advanced stage disease. In evaluating these data, we consider how future directions and advances in proton technology give rise for hope in defining a role for protons in improving NSCLC outcomes. We close with considerations for next steps and the challenges ahead in using proton therapy for this unique patient population.

Early Outcomes of Patients With Locally Advanced Non-small Cell Lung Cancer Treated With Intensity-Modulated Proton Therapy Versus Intensity-Modulated Radiation Therapy: The Mayo Clinic Experience

Purpose

There are very little data available comparing outcomes of intensity-modulated proton therapy (IMPT) to intensity-modulated radiation therapy (IMRT) in patients with locally advanced NSCLC (LA-NSCLC).

Methods

Seventy-nine consecutively treated patients with LA-NSCLC underwent definitive IMPT (n = 33 [42%]) or IMRT (n = 46 [58%]) from 2016 to 2018 at our institution. Survival rates were calculated using the Kaplan-Meier method and compared with the log-rank test. Acute and subacute toxicities were graded based on Common Terminology Criteria for Adverse Events, version 4.03.

Results

Median follow-up was 10.5 months (range, 1-27) for all surviving patients. Most were stage III (80%), received median radiation therapy (RT) dose of 60 Gy (range, 45-72), and had concurrent chemotherapy (65%). At baseline, the IMPT cohort was older (76 vs 69 years, P < .01), were more likely to be oxygen-dependent (18 vs 2%, P = .02), and more often received reirradiation (27 vs 9%, P = .04) than their IMRT counterparts. At 1 year, the IMPT and IMRT cohorts had similar overall survival (68 vs 65%, P = .87), freedom from distant metastasis (71 vs 68%, P = .58), and freedom from locoregional recurrence (86 vs 69%, P = .11), respectively. On multivariate analyses, poorer pulmonary function and older age were associated with grade +3 toxicities during and 3 months after RT, respectively (both P ≤ .02). Only 5 (15%) IMPT and 4 (9%) IMRT patients experienced grade 3 or 4 toxicities 3 months after RT (P = .47). There was 1 treatment-related death from radiation pneumonitis 6 months after IMRT in a patient with idiopathic pulmonary fibrosis.

Conclusions

Compared with IMRT, our early experience suggests that IMPT resulted in similar outcomes in a frailer population of LA-NSCLC who were more often being reirradiated. The role of IMPT remains to be defined prospectively.

Effects of different metastasis patterns, surgery and other factors on the prognosis of patients with stage IV non-small cell lung cancer: A Surveillance, Epidemiology, and End Results (SEER) linked database analysis

The surgical treatment of patients with advanced lung cancer remains controversial. The current study aimed to identify the factors affecting the prognosis of patients with stage IV non-small cell lung cancer (NSCLC) and to clarify the surgery guidelines. A total of 27,725 patients diagnosed with stage IV NSCLC were selected from the Surveillance, Epidemiology, and End Results program between 2010 and 2013. The sex, age, ethnicity, marital status, Tumor-Node-Metastasis stage, radiation therapy received and surgical status of each patient were recorded. Patients were followed up to November 2015. Survival rates were estimated by the Kaplan-Meier method. Single- and multi-factor analyses were performed using the log-rank test and multivariate Cox regression analysis respectively. In the isolated organ metastasis cohort, patients with liver metastasis alone had the worst prognosis, with a median overall survival (OS) of 4 months (liver metastasis vs. other organ metastases; P<0.001). Patients with lung metastasis only had the best prognosis, with a median OS of 8 months (lung metastasis vs. other organ metastases; P<0.001). Furthermore, patients with only one metastasis had the best prognosis, with a median OS of 6 months (single metastasis vs. multiple-organ metastases; P<0.001). The multivariate Cox regression analysis of the isolated-organ metastasis cohort and the multiple-organ metastases cohort revealed that patients who were ≤60 years, female, married, Asian, with N₀ stage, had only bone metastasis, accepted wedge resection or lobectomy of the primary tumor, had surgical procedure to distant lymph node(s), and received beam radiation had an improved prognosis compared with the other patients. Age, sex, tumor type, ethnicity, N stage, number and type of metastatic lesions, surgical treatment of primary and metastatic lesions and radiation therapy are factors which influence the prognosis of patients with stage IV NSCLC. Furthermore, surgery may still benefit these patients.

Proton therapy for small cell lung cancer

The prognosis of limited-stage small cell lung cancer (LS-SCLC) continues to improve and is now roughly comparable to that of locally advanced non-small cell lung cancer (NSCLC). This shift, taken together with the decreased toxicities of modern radiotherapy (RT) for LS-SCLC compared with those reported in historical trials, necessitates further evaluation of whether proton beam therapy (PBT) could further reduce both acute and late toxicities for patients receiving concurrent chemoradiotherapy for LS-SCLC. These notions are discussed theoretically, with an emphasis on cardiac events. This is followed by a review of the published evidence to date demonstrating improved dosimetry with PBT over intensity-modulated RT and encouraging safety and efficacy profiles seen in early clinical reports. In addition to covering technical aspects of PBT for LS-SCLC such as intensity-modulated PBT, image-guidance for PBT, and adaptive planning, this review also discusses the need for increased data on intensity-modulated PBT for LS-SCLC, economic and quality of life analyses for future PBT SCLC studies, careful categorization of cardiac events in these patients, and the role for immunotherapy combined with photon- or proton-based RT for LS-SCLC.

Practice patterns and outcomes of chemoradiotherapy versus radiotherapy alone for older patients with nasopharyngeal cancer

Older patients are at increased risk of toxicities from aggressive oncologic therapy and of nononcologic death. A meta‐analysis of non‐nasopharyngeal head and neck cancers showed no statistical benefit in adding chemotherapy to radiotherapy (RT) in older patients; another meta‐analysis of RT versus chemoradiotherapy (CRT) in NPC found advantages to CRT, but vastly under‐represented patients ≥70 years old. This is the largest study to date evaluating outcomes of CRT versus RT alone in this population. The National Cancer Data Base (NCDB) was queried for primary nasopharyngeal cancer cases (2004–2013) in patients ≥70 years old receiving RT alone or CRT. Patients with unknown RT/chemotherapy and T1N0 or M1 disease were excluded. Logistic regression analysis ascertained factors associated with CRT delivery. Kaplan–Meier analysis evaluated overall survival (OS) between both cohorts. Cox proportional hazards modeling determined variables associated with OS. In total, 930 patients were analyzed (n = 713 (77%) CRT, n = 217 (23%) RT). Groups were relatively balanced; CRT was less frequently delivered in patients with advancing age, lower nodal burden, and females (P < 0.05 for all). Median OS in the CRT and RT groups were 35.3 versus 20.0 months, respectively (P = 0.002). On multivariate analysis, independent predictors of OS included age, comorbidities, income and insurance status, tumor grade, and stage (P < 0.05 for all). Notably, receipt of chemotherapy independently predicted for improved OS (P = 0.036). CRT, compared to RT alone, was independently associated with improved survival in NPC patients ≥70 years old. CRT appears to be a promising approach in this population, but treatment‐related toxicity risks should continue to be weighed against potential oncologic benefits.

Trends in Cardiac Mortality in Patients With Locally Advanced Non-Small Cell Lung Cancer

PURPOSE

To use the Surveillance, Epidemiology, and End Results (SEER) database to compare cardiac-specific mortality (CSM) between left- and right-sided locally advanced non-small cell lung cancer (LA-NSCLC) patients treated with definitive radiation therapy; and to stratify these patients over fixed time intervals to assess for differences in events by treatment era.

METHODS AND MATERIALS

The SEER database was queried for patients with stage III NSCLC who received radiation therapy to compare CSM between left- and right-sided primary cases at 5 time intervals: 1988-1992, 1993-1997, 1998-2002, 2003-2007, and 2008-2012. Cumulative incidence of CSM was compared between left- and right-sided patients using Gray's test. The multivariate Fine and Gray competing risk model was used to compare CSM while accounting for other-cause mortality.

RESULTS

Of 884,610 lung cancer patients, 52,624 met inclusion criteria; of these, 31,549 (60%) were right-sided and 21,075 (40%) were left-sided. When evaluating CSM in each of the 5 time periods, the overall incidence of CSM decreased over time. There was a statistically significant (P<.05) difference based on laterality in all time periods except 1988-1992 (P=.14). The subdistribution hazard ratio for CSM based on disease laterality in all time periods was 1.30 (95% confidence interval 1.18-1.42) and did not discernibly differ by time interval. On multivariate analysis using the Fine and Gray competing risk model, left-sided laterality independently predicted for CSS from 1993 to 2007 (P<.05).

CONCLUSIONS

Cardiac-specific mortality has decreased over time, and left-sided disease independently predicted for CSS during 1993-2007 but not 2008-2012. The time course of cardiac mortality seems to be early, consistent with other studies. These findings underscore the importance of minimizing cardiac irradiation during radiation treatment planning.