Recently published studies suggest that the addition of androgen deprivation therapy to radiation therapy improves outcomes in subsets of men with early prostate cancer.
Early prostate cancer refers to prostate cancer that has not spread from the prostate to distant sites in the body. Standard therapy for early prostate cancer may include surgery, radiation therapy, watchful waiting (no treatment until disease progression), and hormone therapy. Optimal treatment for early prostate cancer is still under debate, though it appears that individualized approaches may provide the best outcomes. Several variables are considered when selecting treatment options for early prostate cancer; these include age, aggressiveness of cancer, extent of spread, other existing medical conditions, and side effects of therapy.
Prostate cancer is stimulated to grow by the male hormone testosterone. Androgen deprivation therapy reduces the amount of circulating testosterone, which ultimately reduces the growth stimulus of prostate cancer. Studies have suggested that the combination of androgen deprivation therapy and radiation therapy results in better outcomes than radiation therapy alone among men with early prostate cancer, but the side effects must be weighed against the benefits.
Researchers from Brigham and Women’s Hospital and Dana Farber Cancer Institute recently conducted a clinical trial to evaluate which subgroups of patients with prostate cancer might benefit from the addition of androgen deprivation therapy to their treatment regimen.(http://news.cancerconnect.com/prostate-cancertipsandrogen-deprivation-benefits-some-patients-with-early-prostate-cancer/#_edn1 "_ednref1") This trial included 206 men with early but aggressive prostate cancer who received either radiation therapy alone or radiation therapy combined with six months of androgen deprivation therapy. Median follow-up was 7.6 years.
- Men treated with androgen deprivation therapy plus radiation therapy had significantly improved survival compared with men treated with radiation therapy only.
- This benefit was, however, limited to men without other significant existing medical conditions. Men who had other significant existing medical conditions did not gain a survival benefit with the addition of androgen deprivation therapy to radiation therapy compared with radiation therapy only.
The researchers concluded that androgen deprivation therapy in addition to radiation therapy does provide a survival benefit among men with early, aggressive prostate cancer. It appears, however, that this benefit is limited to men without other significant existing medical conditions. Further study is necessary to confirm these findings.
Another study explored the effect of adding a shorter course of androgen deprivation therapy to treatment with radiation therapy.(http://news.cancerconnect.com/prostate-cancertipsandrogen-deprivation-benefits-some-patients-with-early-prostate-cancer/#_edn2 "_ednref2") The phase III trial enrolled 456 patients with locally advanced prostate cancer. Half the patients received androgen deprivation therapy starting two months before radiation therapy and then continuing during radiation therapy (total of four months of androgen deprivation therapy), and half the patients received radiation therapy alone.
In addition to overall survival, the researchers assessed disease-specific mortality (the probability of death from prostate cancer or treatment-related complications), disease-free survival (survival free of prostate cancer), distant metastases, and biochemical failure (elevated PSA).
- Ten-year overall survival was 43% among men treated with androgen deprivation therapy plus radiation therapy and 34% among men treated with radiation therapy alone. The difference between study groups did not meet the criteria for statistical significance, suggesting that it could have occurred by chance alone.
- There were statistically significant differences between study groups in 10-year disease-specific mortality (23% versus 36%), disease-free survival (11% versus 3%), distant metastases (35% versus 47%), and biochemical failure (65% versus 80%).
- The risk of fatal cardiac events (12.5% versus 9.1%) did not differ significantly between groups.
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The researchers conclude that these findings “suggest that patients with high-risk, locally advanced disease who decline or who, for medical reasons, are not considered candidates for long-term [androgen deprivation therapy] should be offered short-term neoadjuvant and concurrent [androgen deprivation therapy] in combination with external beam radiation therapy.”
A final study evaluated the effects of exercise on bone mass among men receiving androgen deprivation therapy.(http://news.cancerconnect.com/prostate-cancertipsandrogen-deprivation-benefits-some-patients-with-early-prostate-cancer/#_edn3 "_ednref3") Bone loss is common side effect of androgen deprivation therapy.
The study involved 70 men with early prostate cancer who were scheduled to undergo radiation therapy; half of these patients were also scheduled to receive androgen deprivation therapy. All study participants were sedentary at the start of the study. Half the men were instructed to begin exercising by walking for 20-30 minutes on five or six days per week.
- The men who exercised and received androgen deprivation therapy experienced an increase in their bone mass (0.48% increase).
- Men who did not exercise and received androgen deprivation therapy had a 2.14% decrease in their bone mass.
The researchers concluded that exercise reduces bone loss among men with prostate cancer who are being treated with androgen deprivation therapy. Patients who are receiving androgen deprivation therapy or who are expecting to receive androgen deprivation therapy may wish to speak with their physicians about the risks and benefits of an exercise program.
(http://news.cancerconnect.com/prostate-cancertipsandrogen-deprivation-benefits-some-patients-with-early-prostate-cancer/#_ednref1 "_edn1")D’Amico A, Chen M-H, Renshaw A, Loffredo M, Kantoff P. Androgen suppression and radiation vs radiation alone for prostate cancer. Journal of the American Medical Association. 2008;299:289-295.
(http://news.cancerconnect.com/prostate-cancertipsandrogen-deprivation-benefits-some-patients-with-early-prostate-cancer/#_ednref2 "_edn2")Roach M, Bae K, Speight J et al. Short-term neoadjuvant androgen deprivation therapy and external-beam radiotherapy for locally advanced prostate cancer: Long-term results of RTOG 8610. Journal of Clinical Oncology. 2008;26:585-91
(http://news.cancerconnect.com/prostate-cancertipsandrogen-deprivation-benefits-some-patients-with-early-prostate-cancer/#_ednref3 "_edn3")Chiplis P, et al. Effects of exercise on bone loss and functional capacity during prostate cancer treatment. International Journal of Radiation Oncology, Biology and Physics. 2007;69:supplement S (S321-322).