Contemporary management of metastatic prostate cancer (mPCa) with any of the newer systemic agents that have been approved for castrate-resistant prostate cancer significantly prolongs both cancer-specific and overall survival compared with historical controls, the first population-based study of its kind suggests.
"A population-based study represents the most reliable option for identifying the real effect related to the examined treatment on the overall population," lead author Marco Bandini, MD, Osperdale San Raffaela, Milan, Italy, told Medscape Medical News in an email.
"Our study should encourage urologists and oncologists to intensify the use of such agents in this setting," he added.
The findings were published online November 11 in International Urology and Nephrology.
For their study, Dr Bandini and colleagues analyzed data from the Surveillance Epidemiology and End Results database for 2004 to 2014.
A total of 19,047 men who had been diagnosed with de novo mPCa were identified during the decade-long study interval.
Of this cohort, 4298 patients who received a diagnosis of mPCa between 2004 and 2008 were classified as historical control patients; 4298 men who were diagnosed with mPCa between 2009 and 2014 were classified as contemporary patients.
Because of potentially important confounders related to the year during which the patients were diagnosed, the researchers used a propensity-score matching statistical technique, which allowed them to balance historical cohorts of men who had mPCa with contemporary cohorts of such patients.
The median age of both cohorts was 70 years, and the majority of men had received no local treatment for their cancer.
In a Kaplan-Meir analysis, cancer-specific mortality (CSM) rates were 32 months among historical control patients, compared with 36 months for their contemporary counterparts (P < .0001).
Overall mortality (OM)–free survival rates were shorter for historical control patients, at 26 months, compared with contemporary patients, at 29 months (P < .0001).
On multivariate analysis, cancer-specific mortality rates and OM-free survival rates were 12% lower among contemporary patients compared with historical control patients (hazard ratio [HR] for both endpoints, 0.88; P < .0001).
"To the best of our knowledge, this is the first population-based study that demonstrated improvement in CSM and OM in patients with mPCa since the introduction of several novel agents," the researchers write.
"Our results...provide a valid evidence in support of novel agents," they add.
Five New Drugs in Past Decade
The researchers point out that five new drugs have been approved for the treatment of castrate-resistant prostate cancer during the past decade.
These drugs are docetaxel (multiple brands), approved in 2004; cabazitaxel (Jevtana, Sanofi-Aventis), approved in 2010; sipuleucel-T (Provenge, Dendreon Corp), also approved in 2010; abiraterone (Zytiga, Janssen), approved in 2011; and enzalutamide (Xtandi, Astellas), approved in 2012.
Although the magnitude of the difference in both study endpoints between historical and contemporary cohorts was modest, "in terms of absolute net benefit, we showed 4 months [of benefit] in CSM and 3 [months of benefit] for overall survival [in favor of the contemporary cohort], which is absolutely comparable to the survival advantages showed in the original published trials [for these drugs]," Dr Bandini observed.
He added that, unfortunately, the analysis included only men with metastatic disease, for whom the prognosis is poor regardless of the treatment.
Asked by Medscape Medical News to comment on the new findings, Marc Garnick, MD, clinical professor of medicine, Harvard Medical School and the Beth Israel Deaconess Medical Center, Boston, Massachusetts, said that the study provides important evidence that men with advanced prostate cancer are living longer compared with similar patients who were treated years ago.
"Those who have been practicing for the past 2 decades can appreciate this study's findings that provide quantification for unmistakable observations that men [with advanced prostate cancer] are living long ― sometimes for years," Dr Garnick said in an email.
"[T]he contribution to improved longevity that has accompanied several of the newer anti–prostate cancer therapeutics has been considerable," he added.
The study did not receive any funding. Dr Bandini has disclosed no relevant financial relationships. Dr Garnick is editor-in-chief of Harvard Medical School's Annual Report on Prostate Diseases and its website.
Int Urol Nephrol. Published online November 11, 2017. Abstract
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