Brachytherapy alone is enough for favorable intermediate-risk patients


RTOG 0232 was a large clinical trial conducted to determine whether low-dose-rate brachytherapy (LDR-BT) alone was of equal benefit compared to external beam radiation therapy with a brachytherapy boost (EBRT + LDR-BT) in intermediate-risk patients. The results of this trial were reported earlier this week at the annual meeting of ASTRO in Boston.

The study was conducted at 68 cancer centers in the US and Canada from 2003 to 2012. A total of 588 intermediate-risk men was treated. For the purposes of this study, “intermediate risk” was defined as:

  • Clinical stage T1c to T2b, and
  • Either a Gleason score of 7 and a PSA level of < 10 ng/ml
  • Or a Gleason score of 6 and a PSA level between 10 and 20 ng/ml

The research team did not collect detailed data and report separately those who would now be classified as “favorable intermediate risk” by the Zumsteg definition (Gleason score 3 + 4, less than half the biopsy cores positive, and otherwise low risk). However, Howard Sandler, the Principal Investigator, has written that:

It was deliberately a favorable intermediate group largely. At the time (2002) we felt that combination therapy was mandatory for the more advanced patients and we weren’t comfortable randomizing to brachy alone for those patients.

So it is important that we do not generalize their findings to unfavorable intermediate-risk or high-risk patients.

The patients were treated as follows:

  • LDR-BT: 145 Gy of I-125 seeds or 125 Gy of Pd-103 seeds
  • EBRT + LDR-BT: 45 Gy of EBRT and a boost with 110 Gy of I-125 seeds or 100 Gy of Pd-103 seeds

After 5 years of follow-up:

  • The progression-free survival rates were no different
    • 85 percent for EBRT + LDR-BT patients
    • 86 percent for LDR-BT patients
  • Acute grade 3 (serious) side effects were suffered by 8% in each group.
  • Late-term grade 3 (serious) side effects were higher (12%) in the EBRT + LDR-BT (at 12 percent) compared to the LDR-BT group (at 7 percent).
    • Urinary side effects: 7 percent  in the EBRT + LDR-BT group vs. 3 percent in the LDR-BT group
    • Rectal side effects: 3 percent in the EBRT + LDR-BT group vs. 2 percent in the LDR-BT group

So, the addition of external beam radiation added nothing to cancer control, at least out as long as 5 years, and while side effects were low for both groups, combination therapy increased them.

We saw last year in an analysis of data from patients at Cleveland Clinic who were treated exclusively with BT only (see this link, especially the section on intermediate risk), that progression-free survival was very good for “low intermediate risk” patients. Furthermore, Drs. Stone and Zelefsky agreed that the combination therapy is unnecessary for this group, especially when treated with a sufficient brachytherapy dose. Radiotherapy Clinics of Georgia has built a business out of treating even low-risk patients with the combination therapy. This is now proved to be an over-treatment that is needlessly toxic.

Note: This commentary was written by Allen Edel for The “New” Prostate Cancer InfoLink.

 

One Response

  1. And I would add the same word of caution here that I made about the SBRT data from the recent ASTRO meeting. We really are going to need to know the outcomes of this trial at 10 years too. The current results are very promising, but the 10-year outcomes are the “proof of the pudding” for outcomes in treatment of early stage, localized prostate cancer today.

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