Overall Survival After Treatment of Localized Prostate Cancer With Proton Beam Therapy, External-Beam Photon Therapy, or Brachytherapy

Abstract

With limited high-level evidence, we carried out a comparative effectiveness study for the effect of proton beam therapy (PBT) on overall survival compared to external-beam radiotherapy (EBRT) and brachytherapy (BT) among patients with localized prostate cancer using a national database. PBT was associated with a significant overall survival benefit compared to EBRT and had a similar performance as BT. Background: There are few comparative outcomes data regarding the therapeutic delivery of proton beam therapy (PBT) versus the more widely used photon-based external-beam radiation (EBRT) and brachytherapy (BT). We evaluated the impact of PBT on overall survival (OS) compared to EBRT or BT on patients with localized prostate cancer. Patients and Methods: The National Cancer Data Base (NCDB) was queried for 2004-2015. Men with clinical stage T1-3, N0, M0 prostate cancer treated with radiation, without surgery or chemotherapy, were included. OS, the primary clinical outcome, was fit by Cox proportional hazard model. Propensity score matching was implemented for covariate balance. Results: There were 276,880 eligible patients with a median follow-up of 80.9 months. A total of 4900 (1.8%) received PBT, while 158,111 (57.1%) received EBRT and 113,869 (41.1%) BT. Compared to EBRT and BT, PBT patients were younger and were less likely to be in the high-risk group. On multivariable analysis, compared to PBT, men had worse OS after EBRT (adjusted hazard ratio [HR] ¼ 1.72; 95% confidence interval [CI], 1.51-1.96) or BT (adjusted HR ¼ 1.38; 95% CI, 1.21-1.58). After propensity score matching, the OS benefit of PBT remained significant compared to EBRT (HR ¼ 1.64; 95% CI, 1.32-2.04) but not BT (adjusted HR ¼ 1.18; 95% CI, 0.93-1.48). The improvement in OS with PBT was most prominent in men 65 years old with low-risk disease compared to other subgroups (interaction P < .001). Conclusion: In this national data set, PBT was associated with a significant OS benefit compared to EBRT, and with outcomes similar to BT. These results remain to be validated by ongoing prospective trials.

Association of Race With Receipt of Proton Beam Therapy for Patients With Newly Diagnosed Cancer in the US, 2004-2018

“…Among group 2 cancers, racial disparities in PBT receipt were significant for prostate and breast cancers, the group 2 cancers most frequently treated with PBT, 57 as well as lung and esophagus cancers. Our results are similar to those of older studies that reported racial disparities in receipt of PBT for prostate 7 , 10 , 17 , 25 , 28 and breast cancer. 17 , 26 In prostate cancer, previous studies have shown that White men who reside in more affluent regions and are diagnosed with lower-risk prostate cancer (for which RT provides no survival advantage over active monitoring) 77 are more likely to receive PBT, 7 raising concerns about overtreatment.…”

“…After further matching on health insurance coverage type or income, racial disparities in receipt of PBT narrowed but were not eliminated, suggesting that other factors may contribute to these disparities, such as practitioner referral patterns 10 , 25 , 28 ; practitioner implicit bias, 10 , 28 whereby practitioner treatment recommendations may be influenced by a patient’s race 94 , 95 , 96 ; and patient experiences of discrimination while interacting with the health care system. 97 Increased diversity and training among health care professionals could improve sensitivity to cultural contexts 98 and increase support to strategies that foster systemic changes necessary for equitable access to care.…”

“… 4 , 5 , 6 Previous studies investigating disparities in receipt of PBT evaluated only a single cancer site, 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 age group, 16 or geographic region 17 and, importantly, only included patients receiving RT rather than all patients for whom RT is recommended. Because Black patients are less likely than White patients to receive any type of RT, 3 , 6 , 18 , 19 , 20 , 21 , 22 , 23 , 24 these studies 7 , 10 , 11 , 12 , 13 , 16 , 25 , 26 , 27 , 28 , 29 , 30 might have underestimated the racial disparity in receipt of PBT. Furthermore, differences in referral patterns and regional availability of cancer therapy modalities can influence cancer care receipt 31 , 32 , 33 , 34 , 35 , 36 and racial disparities in access to care.…”

Radiotherapy-Related Gene Signature in Prostate Cancer

“…Due to the extended time-period required for survival analyses in patients with LPCa [ 20 ], we explored the clinical significance of our data using the PRAD dataset. In this database, information from 498 primary tumor samples is available for analysis.…”

Proton Therapy for Prostate Cancer: Challenges and Opportunities

“…The overall survival of localized prostate cancer patients treated with PT, photon-based EBRT, and brachytherapy in the US between 2004 and 2015 were analyzed and compared by Liu et al [ 89 ]. They concluded that PT was associated with a significant overall survival benefit compared to EBRT, and delivered outcomes were similar to brachytherapy.…”