Combining prostate radiotherapy with standard-of-care androgen deprivation therapies (ADT) significantly prolongs survival in patients newly diagnosed with metastatic prostate cancer, according to a recent study at the University of Colorado School of Medicine.
The study, “Improved Survival With Prostate Radiation in Addition to Androgen Deprivation Therapy for Men With Newly Diagnosed Metastatic Prostate Cancer,” published in the Journal of Clinical Oncology, shows that radiotherapy plus ADT therapy nearly doubles survival rates, compared to ADT alone.
Survival is known to be better in metastatic prostate cancer patients when their primary tumor is treated with prostatectomy, but this treatment is invasive and not accessible to all. Recently, prostate radiotherapy has emerged as an attractive treatment strategy for these patients, given its non-invasive administration and the wide range of candidates. Recent studies have also shown that prostate radiotherapy can be used in nonmetastatic prostate cancer (PC) patients to manage their tumors, and increases survival in men with lymph node-positive PC.
To address the benefits of adding prostate radiotherapy to ADT, the researchers used the National Cancer Data Base to identify newly diagnosed advanced PC patients. Between 2004 to 2012, 6,382 men were treated with ADT, 534 of which also received prostate radiotherapy, accounting for 8.4 percent of the examined population.
After a median follow-up of 5.1 years, patients who received radiotherapy in combination with ADT had a significantly higher overall survival (OS), with an OS of 53 months compared to the 29 months in patients who received ADT alone. Consistently, three-year, five-year, and eight-year overall survival was higher in the combination group than in the ADT group. Importantly, the number of patients who survived for at least eight years with ADT plus radiotherapy was more than the double the number of ADT survivors.
After accounting for baseline characteristics, such as age, year, race, comorbidity score, PSA level, Gleason score, and chemotherapy administration, the researchers observed similar results in the OS, with the addition of radiotherapy being always associated with increased overall survival.
The study also showed that patients who receives higher doses of prostate radiotherapy were more likely to have improved survival rates than those who were treated with low-dose radiotherapy.
Researchers believe these results show that treatment of the primary tumor may impact metastasis, thereby increasing their overall survival, and recommend clinical studies to confirm these findings.
However, in an accompanying editorial, Christopher J. Logothetis, MD, department chair and professor in the department of genitourinary medical oncology, and Ana M. Aparicio, MD, an associate professor, both from The University of Texas MD Anderson Cancer Center, believe the researchers did not provide sufficient clinical data to establish the benefit of controlling the primary tumor.
“To better integrate the control of the primary tumor into the therapeutic strategy of men with metastatic prostate cancer, optimum local control must be more specifically defined and developed rationally,” they wrote. “More broadly, one can envisage that strategies integrating organ site-specific therapies targeting the prostate and bone metastases will become a component of an effective treatment strategy for men with potentially lethal prostate cancer.”