THE "NEW" PROSTATE CANCER INFOLINK

A new report from researchers at the University of Florida Proton Therapy Institute offers us some additional information on the short-term outcomes of first-line treatment with image-guided proton beam radiation therapy (PBRT) for localized prostate cancer.

The data reported by Mendenhall et al. are from patients enrolled in three ongoing clinical trials:

• In Trial A, men with low-risk prostate cancer receive  78 cobalt gray equivalents (CGE) in 39 fractions. 
• In Trial B, men with intermediate-risk disease receive dose escalation from 78 to 82 CGE, again in 39 fractions.
• In Trial C, men with high-risk disease receive 78 CGE in 39 fractions with concomitant docetaxel chemotherapy and subsequent androgen deprivation therapy (ADT)

The authors report the following short-term outcomes:

• Data are available on a total of 211 patients.
• 38 percent of patients required preliminary treatment (prior to PBRT) for genitourinary symptoms.
• Average (median) follow-up is 2 years from PBRT.
• Four men ( all of whom had needed preliminary treatment for genitourinary symptoms) had transient Grade 3 genitourinary toxicities during PBRT.
• 88/211 men (42 percent) required treatment for genitourinary symptoms after PBRT.
• Disease progression occurred in one intermediate-risk and two high-risk patients (3/211 or 1.4 percent).
• Grade 3 or higher gastrointestinal symptoms occurred in one one patient.
• Grade 2 and Grade 3 gastrointenstinal symptoms occurred in 0 men (0 percent), 10 (5 percent), 12 (6 percent), and 8 (4 percent) at 6, 12, 18, and 24 months after PBRT.
• The cumulative incidence of Grade 2 and Grade 3 gastrointestinal complications was 20/211 patients (10 percent) at 2 years after PBRT.
• There was a significant correlation between Grade 2+ rectal bleeding and proctitis and the percentage of rectal wall (or rectum) receiving doses ranging from 40 CGE (or 10 CGE for the rectum) to 80 CGE.

The authors conclude that, “Early outcomes with image-guided proton therapy suggest high efficacy and minimal toxicity.”

Unfortunately, this paper offers no data on erectile function at baseline or at any timepoint after PBRT.

We are finally beginning to obtain some meaningful data on the immediate outcomes of men being treated with PBRT for localized prostate cancer. However, we are not sure how to correlate the data presented in this (published) study with the data from 98 patients – also treated at the University of Florida Proton Therapy Institute — that were presented by Hoppe et al. at the annual meeting of ASTRO. It seems very possible that the latter 98 patients are a subset of the current 211 patients.

Filed under: Management, Treatment Tagged: | localized, outcome, PBRT, proton beam radiation