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Long-term androgen deprivation therapy combined with high-dose radiation therapy for prostate cancer improves biochemical control and survival rates

Date:
September 16, 2014
Source:
American Society for Radiation Oncology (ASTRO)
Summary:
Prostate cancer patients who receive high-dose radiation therapy (HDRT) followed by a longer period of hormone suppression therapy, or androgen deprivation therapy (ADT), have higher five-year biochemical, disease-free survival (bDFS) and overall survival rates compared to patients who receive HDRT and a shorter duration of ADT, according to new research.
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Prostate cancer patients who receive high-dose radiation therapy (HDRT) followed by a longer period of hormone suppression therapy, or androgen deprivation therapy (ADT), have higher five-year biochemical, disease-free survival (bDFS) and overall survival rates compared to patients who receive HDRT and a shorter duration of ADT, according to research presented today at the American Society for Radiation Oncology's (ASTRO's) 56th Annual Meeting.

Because prostate cancer cells typically require androgen hormones such as testosterone to grow, ADT is often recommended for patients with prostate cancer. Radiation therapy (RT) combined with ADT is an established, standard of care for patients with locally advanced prostate cancer.

This multi-center study evaluated whether HDRT combined with long-term androgen deprivation (LTAD) therapy for 28 months was associated with better patient outcomes compared to HDRT combined with short-term ADT (STAD) for four months.

Between 2006 and 2010, 362 patients were enrolled in the study at 9 cancer centers in Spain, and 355 patients met all study criteria. The patients had cT1c -- T3aN0M0 prostate cancer (with no lymph node involvement and no metastases and unfavorable risk factors), and prostate specific antigen (PSA) levels of less than 100 ng/ml.

All patients received four months of neoadjuvant and concomitant ADT + HDRT, meaning the ADT was simultaneous to the RT treatment and began prior to radiation in an attempt to reduce tumor size. The median RT dose to the prostate was 78 Gy.

Patients were then randomly assigned to two groups: 177 patients received adjuvant Goserelin (a luteinizing hormone that suppresses production of testosterone) subcutaneously for 24 additional months to form the LTAD group; the remaining 178 patients received only four months of ADT and were categorized as the STAD group. A comparable number of intermediate risk (IR) patients and high-risk (HR) patients were assigned to each group. There were 166 IR patients (85 in the LTAD group; 81 in the STAD group), and 189 HR patients (92 in the LTAD group; 97 in the STAD group).

The study's primary endpoints were bDFS and toxicity scores (radiation-related side effects). The bDFS rate with prostate cancer is based upon the measurement of a patient's PSA level. If a patient's PSA level does not rise upon post-treatment follow-up evaluations, the patient is considered to not be in biochemical failure, or does not have biochemical disease -- meaning the cancer is considered to be ablated and not growing or spreading.

A total of 11 patients in the LTAD group and 15 patients in the STAD group had bDFS, according to Phoenix Consensus definition (p=0.003).

After a median follow-up of 63 months, the five-year bDFS was significantly higher in the LTAD group (89.8 percent, compared to the STAD group (81.3 percent) (p=0.019). The study also evaluated metastasis free survival (MFS) and overall survival (OS). The five-year MFS was also significantly higher for the LTAD group -- 93.6 percent compared to 83.4 percent in the STAD group (p=0.009). There was also a significant benefit in the OS for patients treated with LTAD (94.8 percent) versus STAD (86.1 percent, p=0.009), this benefit being more evident in patients with high-risk prostate cancer (p=0.010). Radiation-related side effects of ≥Grade 2 were acceptably low and not significantly different in both groups.

"The management of patients with intermediate- and high-risk prostate cancer is highly challenging," said lead study author Almudena Zapatero, MD, PhD, a radiation oncologist at Hospital Universitario de la Princesa in Madrid Spain. "The clinician must choose the type of local treatment as well as the optimal timing and sequence of hormone therapy. Moreover, rapid and ongoing advances in treatment options require that physicians consider options that can impact both survival and quality-of-life. The five-year results of our study show that the combination of high-dose external radiotherapy utilizing new technologies, such as IMRT, VAMT and IGRT, and 28 months of hormone therapy are a very successful combination to achieve positive prostate cancer control. Of paramount consideration, LTAD therapy in combination with HDRT provides good quality of life through a non-invasive, safe and efficient treatment approach for patients with high-risk prostate cancer."


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Materials provided by American Society for Radiation Oncology (ASTRO). Note: Content may be edited for style and length.


Cite This Page:

American Society for Radiation Oncology (ASTRO). "Long-term androgen deprivation therapy combined with high-dose radiation therapy for prostate cancer improves biochemical control and survival rates." ScienceDaily. ScienceDaily, 16 September 2014. <www.sciencedaily.com/releases/2014/09/140916092015.htm>.
American Society for Radiation Oncology (ASTRO). (2014, September 16). Long-term androgen deprivation therapy combined with high-dose radiation therapy for prostate cancer improves biochemical control and survival rates. ScienceDaily. Retrieved June 17, 2024 from www.sciencedaily.com/releases/2014/09/140916092015.htm
American Society for Radiation Oncology (ASTRO). "Long-term androgen deprivation therapy combined with high-dose radiation therapy for prostate cancer improves biochemical control and survival rates." ScienceDaily. www.sciencedaily.com/releases/2014/09/140916092015.htm (accessed June 17, 2024).

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