Toxic side effects of adjuvant, salvage IMRT post-surgery

Prostate cancer patients are commonly concerned about the potential risks for side effects associated with adjuvant and salvage radiation therapy after a preceding, first-line, radical prostatectomy.

Deville et al. have carried out a retrospective analysis of the toxicities associated with intensity-modulated radiation therapy (IMRT) when used to treat men who had previously undergone radical prostatectomy. Their goal was to assess the relative risks of increased toxicity in men receiving IMRT to the whole pelvis as opposed to those receiving radiation only to the prostate bed.

The study included 67 patients treated at the authors’ institution between January 2006 and January 2009 who were followed for not less than 12 months after their radiation. All patients had received a prior radical prostatectomy; they all received a total radiation dose of 70.2 Gy delivered by IMRT; and the patients being given whole pelvis radiation received an initial dose of 45 Gy to the pelvic nodal area.

The key results of the study were as follows:

  • 36 patients received whole pelvis radiation.
  • 31 patients received prostate bed radiation alone.
  • Pretreatment demographics (e.g., age and co-morbidities) were similar between the two groups.
  • Compared to patients recommended for prostate bed radiation alone, patients recommended for whole pelvis radiation
    • Had more aggressive disease (i.e., higher Gleason scores, higher T stages, and higher pre-surgical PSA levels)
    • Were more likely to receive concomitant androgen deprivation therapy (ADT)
    • Had higher doses of radiation to the bowel, bladder, and rectum
  • Patients who received whole pelvis radiation had a 61 percent risk for acute gastrointestinal (GI) toxicity.
  • Patients who received prostate bed radiation only had a 29 percent risk for acute GI toxicity.
  • The highest level of acute GI toxicity was Grade 2.
  • There was a numerical difference but no statistically significant difference in other forms of toxicity between the two groups of patients at a median 25 months of follow-up (range, 12 to 44 months).
    • Acute genitourinary (GU) toxicities of Grade 2 or higher — 22 percent in whole pelvis group vs. 10 percent in prostate bed group; p = 0.193.
    • Late GI toxicities of Grade 2 or higher — 3 percent in whole pelvis group vs. 0 percent in prostate bed group; p = 0.678.
    • Late GU toxicities of Grade 2 or higher — 28 percent in whole pelvis group vs. 19 percent in prostate bed group; p = 0.274.
  • On multivariate analysis, long-term use of ADT was associated with late GU toxicities of Grade 2 or higher (p = 0.02).

The authors conclude that there is a clinically significant increase in risk for acute GI toxicities of Grade 2 and lower in men receiving IMRT to the whole pelvis as adjuvant or second-line treatment compared to men receiving IMRT only to the prostate bed. However, there are no differences in the level of risk for late GI or any GU toxicities unless patients were also receiving ADT.

2 Responses

  1. Rarely does one see such an obvious no-brainer that has apparently gone over the heads of “the experts”. The difference in toxicities and side-effects between the two treatments is the stupidity of subjecting a patient to an individual 45 Gy dose of radiation. The highest individual dose that should ever be used for such treatment is about 2 Gy. With 45 Gy you can almost cut through a metal bar! …so, duh!, of course patients suffered damage!

    This a study for the trash can. It doesn’t compare radiation to the prostate bed to that of the pelvis. It compares subjecting some men to reasonable doses of radiation vs. frying the guts out of men with a mega-dose far beyond what ought even to be allowed. Heck, why not send them into that Japanese nuclear reactor to spend a day or two? I bet that would result in some toxicities too!

  2. Dear Mr. Arnold:

    I suspect that this would imply a total initial dose per individual of 45 Gy to the pelvis over 25 or 30 sessions and not a single dose of 45 Gy at one session.

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