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Intermediate-Risk Patients With Organ-Confined Prostate Cancer Have High Cancer-Free Survival Rate After Stereotactic Body Radiation Therapy

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BOSTON, Oct. 30, 2012 (GLOBE NEWSWIRE) -- Stereotactic body radiotherapy (SBRT) yields excellent cancer-free survival rates for intermediate-risk, organ-confined prostate cancer patients and results in few long-term rectal side effects, according to research presented today at the American Society for Radiation Oncology's (ASTRO's) 54th Annual Meeting.

The phase II, prospective, multi-institutional study evaluated the toxicity and efficacy of SBRT in 129 intermediate-risk, organ-confined prostate cancer patients treated from 2007 to 2010 with a median follow up of 36* months (* updated data). Results demonstrate that three years after SBRT treatment, 99 percent of patients were cancer-free, with only one patient experiencing cancer recurrence. There were no reports of acute grade 3 to 5 toxicity. Twenty-three percent of patients (30) experienced acute (temporary) grade 2 genitourinary (GU) toxicity, and 8.5 percent of patients (11) experienced acute gastrointestinal (GI) toxicity with SBRT. Late grade 2 GU and GI toxicities occurred in 11 percent (14) and two percent of patients (3), respectively. One patient had a grade 3 bladder neck injury one year after treatment; there were no other grade 3 to 5 toxicities.

This study also examined the effects on a patient's quality of life using the Expanded Prostate Cancer Index Composite (EPIC-26) questionnaire for urinary, bowel and sexual function and determined that the results appear favorable compared to other radiotherapy modalities. Patients' urinary and bowel functions were lower one month after treatment but returned to normal by 24 months, as indicated by their EPIC scores. One patient required temporary catheter placement for acute urinary retention. At baseline, 52 percent of patients were potent, declining to 36 percent at 24 months.

The study included patients from 21 institutions who exhibited a pre-treatment median prostate-specific antigen (PSA) of 5.9 ng/ml, which decreased to 0.8, 0.4 and 0.2 ng/ml at one, two and three years, respectively. Patients were treated for one week with a non-isocentric robotic SBRT platform using real-time tracking of implanted fiducials, and magnetic resonance imaging was used to assist in target localization. SBRT was administered to patients at 40 Gy in 5 fractions of 8 Gy to the prostate, and 36.25 Gy was delivered to seminal vesicles. No patient had androgen deprivation therapy. Toxicities were assessed using common terminology criteria for adverse events (CTCAE, v3). Patients with erections "firm enough for intercourse" were scored as potent.

"Patients with intermediate-risk, organ-confined prostate cancer, at a median age of 69, are at risk for progression and spread of the disease, when it becomes more difficult to treat. Our study demonstrates very promising cancer control rates and few side effects from SBRT," said Robert Meier, MD, lead author of the study and a radiation oncologist at the Swedish Radiosurgery Center in Seattle. "With further research and longer follow-up assessments, this could result in patients undergoing a much shorter treatment schedule of just one week of SBRT as opposed to the standard eight to nine week course needed with other radiation methods."

The abstract, "Stereotactic Body Radiotherapy for Intermediate-risk Organ-confined Prostate Cancer: Interim Toxicity and Quality of Life Outcomes from a Multi-Institutional Study," will be presented in detail during a scientific session at ASTRO's Annual Meeting at 1:30 p.m. Eastern time on Wednesday, October 31, 2012. To speak with Dr. Meier, call Michelle Kirkwood on October 28 – 31, 2012, in the ASTRO Press Office at the Boston Convention and Exhibition Center at 617-954-3461 or 617-954-3462, or email michellek@astro.org.

ASTRO's 54th Annual Meeting, held in Boston, October 28 – 31, 2012, is the premier scientific meeting in radiation oncology and brings together more than 11,000 attendees including oncologists from all disciplines, medical physicists, dosimetrists, radiation therapists, radiation oncology nurses and nurse practitioners, biologists, physician assistants, practice administrators, industry representatives and other health care professionals from around the world. The theme of the 2012 Annual Meeting is "Advancing Patient Care through Innovation" and examines how innovation in technology and patient care delivery can lead to improved patient outcomes. The four-day scientific meeting includes six plenary papers and 410 oral presentations in 63 oral scientific sessions, and 1,724 posters and 130 digital posters in 18 tracks/topic areas.

ABOUT ASTRO

ASTRO is the largest radiation oncology society in the world, with more than 10,000 members who specialize in treating patients with radiation therapies. As the leading organization in radiation oncology, biology and physics, the Society is dedicated to improving patient care through education, clinical practice, advancement of science and advocacy. For more information on radiation therapy, visit www.rtanswers.org. To learn more about ASTRO, visit www.astro.org.

2012 American Society for Radiation Oncology (ASTRO) 54th Annual Meeting

News Briefing, Tuesday, October 30, 2012, 3:15 p.m. – 4:00 p.m. Eastern time

Scientific Session: Wednesday, October 31, 2012, 1:30 – 3:00 p.m. ET, Boston Convention & Exhibition Center

366  Stereotactic Body Radiotherapy for Intermediate-risk Organ-confined Prostate Cancer: Interim Toxicity and Quality of Life Outcomes from a Multi-Institutional Study

R. Meier1, I. Kaplan2, A. Beckman3, G. Henning4, S. Woodhouse5, S. Williamson6, N. Mohideen7, D. Herold8, C. Cotrutz1, M. Sanda2, 1Swedish Cancer Institute, Seattle, WA, 2Beth Israel Deaconess Medical Center, Boston, MA, 3Central Baptist Hospital, Lexington, KY, 4St. Joseph Mercy Hospital System, Ypsilanti, MI, 5Community Cancer Center, Normal, IL, 6Capital Health System, Trenton, NJ, 7Northwest Community Hospital, Arlington Heights, IL, 8Jupiter Medical Center, Jupiter, FL

Purpose/Objective(s): A phase II prospective multi-center study* was initiated in 2007 to evaluate the toxicity and efficacy of stereotactic body radiotherapy (SBRT) for organ-confined prostate cancer. The study included 21 institutions and completed accrual in 2011. We report an interim analysis of toxicities, quality of life (QoL) and early PSA outcomes of the intermediate-risk cohort.

Materials/Methods: A total of 129 hormone-naïve intermediate-risk patients (CS T1c-T2b, N0-x, M0-x, with either Gleason = 7 & PSA less than 10 ng/ml, or Gleason less than or equal to 6 & PSA between 10-20) with biopsy proven adenocarcinoma of the prostate were enrolled. MR imaging was used to assist in target localization. All patients were treated with a non-isocentric robotic SBRT platform using real-time tracking of implanted fiducials. The prostate was prescribed 40 Gy in 5 fractions of 8 Gy and seminal vesicles received 36.25 Gy. No patient had androgen deprivation therapy. Toxicities were assessed using CTCAE v3 criteria. QoL for urinary, bowel and sexual function were assessed using the Expanded Prostate Cancer Index Composite (EPIC-26) questionnaire; patients with erections "Firm enough for intercourse" on question 9 were scored as potent. Biochemical failure was defined as a 2 ng/ml rise above nadir.

Results: Median follow-up was 30 months (range 10-42 months). No acute grade 3+ toxicities were reported. Acute Grade 2 GU and GI toxicities occurred in 20% and 8.5% of patients, respectively. One patient required temporary catheter placement for acute urinary retention. Late Grade 2 GU and GI toxicities occurred in 10% and 2% of patients, respectively. One late Grade 3 GU toxicity (bladder neck injury 1 year after treatment) was reported. There were no other Grade 3-5 toxicities. Mean EPIC urinary and bowel scores fell at 1 month and returned to baseline by 24 months. At baseline 52% of patients were potent, declining to 35% at 24 months. Pre-treatment median PSA was 5.93 ng/ml, decreasing to 0.80, 0.38 and 0.20 ng/ml at 1, 2 and 3 years, respectively. One patient had a biochemical failure at 3 months follow-up due to a biopsy-proven nodal metastasis. No other biochemical failures have been observed, resulting in a 3-year Kaplan-Meier biochemical progression-free survival rate of 99.2%.

Conclusions: In a multi-institutional study employing CyberKnife SBRT in intermediate-risk prostate cancer patients, serious acute and late toxicities have been minimal. EPIC urinary, bowel and sexual function responses appear favorable compared to other radiotherapy modalities. Early PSA responses are promising. With further follow-up, this study will help determine whether SBRT provides a therapeutic gain in the treatment of organ-confined prostate cancer.

*ClinicalTrials.gov identifier NCT00643994: supported by a grant from Accuray Inc

Author Disclosure Block:

R. Meier: None. I. Kaplan: None. A. Beckman: None. G. Henning: None. S. Woodhouse: None. S. Williamson: None. N. Mohideen: None. D. Herold: None. C. Cotrutz: D. Employment Other; Spouse employed by Accuray. M. Sanda: None.

CONTACT: Michelle Kirkwood, 703-286-1600, michellek@astro.org
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