Prolongation of total treatment time because of infrequently missed days of treatment is not associated with inferior biochemical outcome after dose-escalated radiation therapy for prostate cancer

Treatment Interruptions During Stereotactic Body Radiotherapy for Prostate Cancer

Background

During the course of radiation treatment for prostate cancer, patients may have unintentional interruptions in their treatment course due to a wide variety of factors. Stereotactic body radiation therapy (SBRT) decreases the number of treatments compared to conventionally fractionated radiation; hence, it has the potential to decrease treatment delays and non-completion. This study sought to determine the incidence of treatment delay and characterize the etiology and length in a large cohort of men treated with SBRT for their prostate cancer.

Methods

One thousand three hundred and thirty-six patients treated with SBRT from 2008 to 2021 at the Georgetown University Hospital for prostate cancer were included in this retrospective study. A treatment delay was defined as a patient requiring longer than 14 days to complete 5 fractions of SBRT. Non-completion was defined as patients treated with less than 5 fractions. In the patients who experienced delays, chart review was performed to characterize the length and etiology of each delay. Multivariate analysis was performed via binary logistic regression modeling on PSPP.

Results

All individuals in the cohort eventually completed the planned 5-fraction regimen. Thirty-three patients experienced a treatment delay. Median length of time to complete treatment was 11 days (range 5–155 days). In patients who experienced a delay, nearly half (45.5%) experienced only a one-day delay. The most common reason for a delay was a technical issue (48.5%), including the machine maintenance, fiducial misalignment, or inadequate pretreatment bowel preparation. Other reasons included unplanned breaks due to acute side effects (21.2%), logistical issues (18.2%), non-treatment related health issues (9.1%), and inclement weather (3.0%). There were no significant sociodemographic, oncologic, or treatment variables that predicted treatment interruption on multivariate analysis.

Conclusions

The incidence of treatment interruptions in patients undergoing SBRT for their prostate cancer was low. Most treatment delays were short.

Optimal timing of radiotherapy in high risk prostate cancer: Do missed days matter?

Introduction

High-risk prostate cancer is associated with poorer overall survival (OS) and biochemical control compared to more favorable risk groups. External beam radiation therapy (EBRT) is widely used; however, outcomes data are limited with respect to time elapsed between diagnosis and initiation of EBRT.

Methods

The National Cancer Database was queried from 2004 to 2015 for patients diagnosed with high-risk adenocarcinoma of the prostate who received androgen deprivation therapy (ADT) and definitive EBRT. Logistic regression was utilized to determine covariates associated with missing EBRT treatments. OS was analyzed using multivariate cox proportional hazards models and propensity score matching.

Results

9,610 patients met inclusion criteria with median follow-up of 40.6 months and median age of 72 years. Median PSA was 8.7 and median EBRT dose was 78 Gy. ADT was initiated at a median of 36 days and EBRT at a median of 63 days post-diagnosis. Median number of prolonged treatment days was 2.2. Black race (OR: 1.40; p < 0.01), treatment at a community clinic (OR: 1.32; p < 0.01), and living in an urban/densely populated area were associated with prolonged treatment. Time elapsed between ADT and EBRT > 74 days (HR: 1.20; p = 0.01) and prolonged treatment>3 days of EBRT (HR: 1.26; p = 0.005) were associated with an increased hazard of death. The 5-year OS was 79.6% and 82.9% for patients with prolonged treatment of 3 days or more of EBRT and those missing 3 days or less, respectively (p = 0.0006).

Conclusion

In this hypothesis-generating study, prolonged treatment delays and missing three or more EBRT treatments was associated with poorer OS in patients with high-risk adenocarcinoma of the prostate.

Treatment interruptions affect biochemical failure rates in prostate cancer patients treated with proton beam therapy: Report from the multi-institutional proton collaborative group registry

INTRODUCTION

To date, no studies examining the effect of treatment interruptions (TI) with proton beam therapy (PBT) have been published. The goal of our study was to determine the predictors of TI amongst patients with prostate cancer (PCa) treated with PBT and to determine whether TI are associated with biochemical failure (BF). We hypothesized that any correlation between TI and biochemical control would be more pronounced in high risk groups.

METHODS

Data for 4278 patients with PCa was obtained from the prospectively collected Proton Collaborative Group (PCG) data registry. Univariate and multivariate logistic regression analysis (MVA) was used to model possible predictors of BF. A subset analysis was performed for high risk patients treated with ADT and PBT. Finally, propensity score (PS) analysis was performed to account for any indication bias caused by lack of randomization.

RESULTS

Total treatment duration (OR, 1.05 [1.04-1.06]; p < 0.001) increased the likelihood of TI on MVA. TI did not have a statistically significant correlation with BF (OR, 1.44 [0.86-2.39]; p = 0.162) amongst PS matched patients. However, on subset analyses of high risk group patients with PS matching, there was a trend towards worse BF in patients with TI (OR 3.85; 95%CI (0.96-15.44); p = 0.057).

CONCLUSION

In the first analysis of its kind, the results suggest that TI in high risk PCa patients treated with PBT and ADT have worse BF rates. Interventions such as increased patient education, proper maintenance of proton facilities, and decreasing total treatment duration with alternative fractionation schedules may help avoid the unintended negative effects on tumor control due to TI. However, future analyses on a larger patient population is needed.

Effects of interruptions of external beam radiation therapy on outcomes in patients with prostate cancer

INTRODUCTION

To evaluate if interruptions of external beam radiation therapy impact outcomes in men with localized prostate cancer (PCa).

METHODS

We included men with localized PCa treated with three-dimensional conformal radiotherapy (3D-CRT) or intensity-modulated radiation therapy (IMRT) of escalated dose (≥74 Gy in 1.8 or 2 Gy fractions) between 1992 and 2013 at an NCI-designated cancer centre. Men receiving androgen deprivation therapy were excluded. The non-treatment day ratio (NTDR) was defined as the number of non-treatment days divided by the total elapsed days of therapy. NTDR was analysed for each National Comprehensive Cancer Network (NCCN) risk group.

RESULTS

There were 1728 men included (839 low-risk, 776 intermediate-risk and 113 high-risk), with a median follow up of 53.5 months (range 12-185.8). The median NTDR was 31% (range 23-71%), translating to approximately 2 breaks (each break represents a missed treatment that will be made up) for 8 weeks of RT with 5 treatments per week. The 75 percentile of NTDR was 33%, translating to approximately 4 breaks, which was used as the cutoff for analysis. There were no significant differences in freedom from biochemical failure, freedom from distant metastasis, cancer specific survival, or overall survival for men with NTDR ≥33% compared to NTDR<33% for each risk group. Multivariable analyses including NTDR, age, race, Gleason score, T stage, and PSA were performed using the proportional hazards regression procedure. NTDR≥33% was not significantly associated with increased hazard ratio for outcomes in each risk group compared to NTDR<33%.

CONCLUSION

Unintentional treatment breaks during dose escalated external beam radiation therapy for PCa did not cause a significant difference in outcomes, although duration of follow up limits the strength of this conclusion.

Effect of Patient Demographic Characteristics and Radiation Timing on PSA Reduction in Patients Treated With Definitive Radiation Therapy for Prostate Cancer

INTRODUCTION

The purpose of this study was to assess how demographic characteristics and temporal factors including time to treatment (TTT) and elapsed time of treatment (ETT) affect prostate-specific antigen (PSA) levels during and after radiation treatment for low- and intermediate-risk prostate cancer.

PATIENTS AND METHODS

A retrospective review of 1584 patients was conducted on patients diagnosed with prostate cancer between 2005 and 2013, from which 147 patients were found to have completed definitive external beam radiation therapy (EBRT) monotherapy. Demographic data, TTT (days between diagnosis and EBRT start date), ETT (days between EBRT start and stop date), and Gleason score were collected on these patients and analysis of variance was performed to analyze the relationship of these factors with PSA changes. PSA changes were calculated during treatment as the difference between pre- and posttreatment PSA levels and after treatment as 3-year and overall PSA velocities.

RESULTS

Patients who spoke Haitian Creole (P = .039) and those with a longer ETT (P = .029) had significantly greater PSA decline during treatment, primarily as a result of higher pretreatment PSA levels. Patients with Gleason score 4+3 disease had significantly greater 3-year (P = .033) and overall (P = .019) PSA velocities. Race and/or ethnicity, insurance type, marital status, and age were not associated with any PSA variable.

CONCLUSION

Disparities in prostate cancer are not reflected in PSA dynamics during or after radiation treatment, but are evident in PSA level at presentation. Timeliness of treatment was not found to affect true PSA change due to EBRT in low- and intermediate-risk prostate cancer patients.

Phase I/II trial of definitive carbon ion radiotherapy for prostate cancer: evaluation of shortening of treatment period to 3 weeks

BACKGROUND

The purpose of this study was to evaluate the feasibility of a new shortened 3-week treatment schedule of carbon ion radiotherapy (CIRT) for prostate cancer.

METHODS

Beginning in May 2010, patients with T1b-T3bN0M0, histologically proven prostate adenocarcinoma were enrolled in the phase II trial of CIRT. Patients received 51.6 GyE in 12 fractions over 3 weeks (protocol 1002). The primary end point was defined as the incidence of late adverse events that were evaluated based on the Common Terminology Criteria for Adverse Events version 4.0. Biochemical failure was determined using the Phoenix definition (nadir +2.0 ng ml(-1)).

RESULTS

Forty-six patients were enrolled, and all patients were included in the analysis. The number of low-, intermediate-, and high-risk patients was 12 (26%), 9 (20%), and 25 (54%), respectively. The median follow-up period of surviving patients was 32.3 months. Two patients had intercurrent death without recurrence, and the remaining 44 patients were alive at the time of this analysis. In the analysis of late toxicities, grade 1 (G1) rectal haemorrhage was observed in 3 (7%) patients. The incidence of G1 haematuria was observed in 6 (13%) patients, and G1 urinary frequency was observed in 17 (37%) patients. No ⩾G2 late toxicities were observed. In the analysis of acute toxicities, 2 (4%) patients showed G2 urinary frequency, and no other G2 acute toxicities were observed.

CONCLUSIONS

The new shortened CIRT schedule over 3 weeks was considered as feasible. The analysis of long-term outcome is warranted.