The Addition of Brachytherapy to External Beam Radiation Improve Outcomes

Cancer Connect

by Dr. C.H. Weaver M.D. updated 6/2020

Patients with advanced localized prostate cancer have cancer that has spread outside the prostate, but not to distant sites in the body. A common form of treatment for these patients is external beam radiation therapy (EBRT), in which high-dose x-rays from a machine are aimed at the affected area. Another form of radiation therapy, called brachytherapy, involves the placement of small “seeds” of radioactive material directly into the prostate gland. Brachytherapy has been used extensively to treat earlier stage prostate cancer and is also used to augment EBRT for patients with advanced localized prostate cancer. Research suggests that the use of brachytherapy in addition to EBRT may be more effective treatment than EBRT alone for patients with advanced localized prostate cancer. (1,2)

The prostate is a male sex gland that is located between the bladder and the rectum. Cancer of the prostate occurs commonly in older men. One test used to determine the stage of prostate cancer is the measurement of prostate specific antigen (PSA) levels in the blood. Prostate specific antigens are proteins normally produced by the prostate, but when found in high levels in the blood indicate the presence of prostate cancer. Higher levels of PSA correlate to more advanced stages of prostate cancer.

Researchers evaluated the effectiveness of brachytherapy plus EBRT versus EBRT alone in the treatment of over 300 patients with advanced localized prostate cancer. Half of the patients received treatment consisting of both brachytherapy and EBRT and the other half received EBRT alone. Five years following treatment, high PSA levels existed in only 33% of patients that had received the combination of brachytherapy plus EBRT compared to 56% of patients that received EBRT alone. Since high PSA levels are an indication of the presence of cancer, these results suggest that brachytherapy plus EBRT may be more effective than EBRT alone in the treatment of advanced localized prostate cancer.

Additional research has confirmed that the combination of brachytherapy plus EBRT provides low rates of cancer recurrences at 15 years following treatment for early prostate cancer.
Researchers from several medical institutions the results of a trial that included 223 patients who were first treated with EBRT followed by brachytherapy over 15 years ago.

  • Biochemical relapse-free survival IBRDS)-no two consecutive rises in PSA levels-was achieved in 74% of patients. BRFS was 88% among patients who were at a low-risk for developing a recurrence, 80% among patients who were at an intermediate-risk for developing a recurrence, and 53% among patients who were at a high risk for developing a recurrence.

The combination of EBRT and brachytherapy provides impressive BRFS rates at 15 years following therapy for patients with early prostate cancer. Patients with early prostate cancer may wish to speak with their physician regarding their individual risks and benefits of this approach.

ADT Plus EBRT Improves Survival in Prostate Cancer Over Brachytherapy Plus EBRT

Evaluation of practice patterns suggests that some physicians don't offer androgen-deprivation therapy (ADT) to early stage prostate cancer patients they have treated with EBRT and brachytherapy. Research suggests that omitting ADT in favor of EBRT plus brachytherapy may lessen overall survival compared with EBRT plus ADT in patients with intermediate- and high-risk prostate cancer. In a meta - analyses of over 5000 patients it has been reported that omitting ADT reduces overall survival in men with intermediate- and high-risk prostate cancer. ADT for these men should remain a component of treatment regardless of radiotherapy delivery method until definitive evidence demonstrates otherwise. (4)

Reference:

  1. Journal of Clinical Oncology, Vol 18, No 15, pp 2869 – 2880
  2. Jani AB, Feinstein JM, Pasciak R Krengel S, Weichselbaum RR. Role of External Beam Radiotherapy with Low-dose-rate Brachytherapy in Treatment of Prostate Cancer. Urology. 2006;67:1007-1011.
  3. Sylvester J, Grimm P, Blasko J, et al. 15-Year Biochemical Relapse Free Survival in Clinical Stage T1-T3 Prostate Cancer Following Combined External Beam Radiotherapy and Brachytherapy; Seattle Experience. International Journal of Radiation Oncology, Biology, Physics. 2007; 67: 57-64.
  4. J Clin Oncol. 2020 May 12. Epub ahead of print.

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