Is combination EBRT + LDR-BT worth the risk for most patients?

Long-term data from the Radiaton Treatment Oncology Group (RTOG) 00-19 Phase II trial of external beam radiation therapy (EBRT) + low-dose-rate permanent implant brachytherapy (LDR-BT) has suggested that this type of radiation treatment is probably no more effective than either EBRT or LDR-BT alone … but does have a greater risk for long-term side effects.

Lawton et al. have just published data from this 138-patient clinical trial in “The Red Journal”. Patients were enrolled from 20 different institutions. All patients were initially treated with 45 Gy of external beam radiation in 25 fractions and then with 108 Gy given as permanent 125-iodine seed implants.

Here are the core results of the RTOG study:

  • Data from 131/138 patients were eligible for analysis.
  • The average (median) follow-up among living patients was 8.2 years (range, 2.7 to 9.3 years).
  • The 8-year estimate of biochemical failure was
    • 18 percent based on the Phoenix definition of biochemical failure (nadir PSA + 2 ng/ml)
    • 21 percent based on the ASTRO consensus definition (three consecutive rises in PSA levels above the nadir level).
  • The 8-year estimate of late grade 3/4 genitourinary and/or gastrointestinal toxicities was 15 percent.
  • The most common grade 3/4 toxicities were urinary frequency, dysuria, and proctitis.
  • There were two grade 4 toxicities (both bladder necroses) and no grade 5 toxicities.
  • 42 percent of patients reported grade 3 impotence (no erections) at 8 years.

The authors conclude that biochemical control achieve using this form of combination radiation therapy “seems durable with 8 years of follow-up.” However, they go on to note that these rates of biochemical control are very comparable to those achieved uesing EBRT or LDR-BT alone.

In addition, they note that “Late toxicity in this multi-institutional trial is higher than reports from similar cohorts of patients treated with high-dose [EBRT] alone or permanent [LDR-BT] alone.”

3 Responses

  1. The dosage sounds strange. In my case, and with other men I have known to receive similar treatment, the seed dosage is a lot lower. In my case I received around 43 Gy IMRT + 54 Gy of brachytherapy (with iodine-125) for a total of 97 Gy. Men that I have known through my support group activities receiving EBRT or brachtherapy alone usually received less than that — around 70-80 Gy.

    The large dosage of 153 Gy may have significant bearing on the higher incidence of long term co-morbidity. I would be curious to learn the dosages used on others reading this post who received combination treatment. I would also like to hear a professional’s response to this study.

  2. Think of all the men unnecessarily damaged for no benefit.

  3. I received 85 Gy of palladium-105 and 45 Gy of photon therapy for a total of 130 Gy. Three years out I have no side effects, ED, urinary, or bowel issues and PSA has been a consistent 0.1 ng/ml after an initial PSA of 40 and Gleason 4 + 3 = 7 disease.

    150 Gy may be overkill leading to additional side effects.

    John T.

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