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Aspirin May Improve Prostate CA Outcomes
  MedPage Today
Published: October 27, 2010
SAN DIEGO -- Prostate cancer patients had almost a 60% lower disease-specific mortality if they used anticoagulants, particularly aspirin, an analysis of a large prostate cancer database showed.
Multivariate analysis yielded a hazard ratio of 0.44 for prostate cancer mortality among anticoagulant users followed for 10 years (P<0.01 versus nonusers). Patients with high-risk prostate cancer had an 80% lower risk of disease-specific mortality if they used anticoagulants, according to a study that will be reported at the upcoming American Society for Radiation Oncology meeting.
The survival benefit was driven primarily by aspirin use, as use of other anticoagulants without aspirin resulted in a nonsignificant decrease in prostate cancer-specific mortality.
Action Points
* Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
* Note that the results of this study suggest an association between use of aspirin and reduced mortality from prostate cancer, particularly in patients with high-risk disease.
"Use of anticoagulants was associated with a reduced risk of prostate cancer-specific mortality, regardless of treatment modality," Kevin Choe, MD, of the University of Texas Southwestern Medical Center in Dallas, said at a news briefing prior to the meeting.
"The possible mechanisms behind this effect are diverse and not well understood, but they may involve inhibition of distant metastasis."
Several lines of evidence have established an association between malignancy and the coagulation system. Cancer patients have an increased risk of thromboembolism, and patients with a history of venous thromboembolism have an increased cancer risk. Experimental data have implicated the coagulation system in multiple cancer pathways, including proliferation, angiogenesis, apoptosis, and metastasis, said Choe.
However, clinical studies have produced limited and inconclusive evidence to support the coagulation-malignancy link, he continued.
Prostate cancer offers a potentially useful clinical model to study the relationship between coagulation and cancer, as patients tend to be older and often have cardiovascular comorbidities that require anticoagulant therapy. Choe and colleagues recently reported that patients with localized prostate cancer treated with radiation therapy alone had better biochemical control if they were taking anticoagulants (Cancer 2010; 116: 1820-1826).
To examine the association in a larger patient cohort, investigators analyzed the CapSURE (Cancer of the Prostate Strategic Urological Research Endeavor) database of almost 14,000 men with biopsy-proven prostate cancer. Choe and colleagues limited the analysis to 5,295 men with localized disease, whose medication use was reported, and who were treated with surgery or primary radiation therapy (no adjuvant irradiation).
The analysis included 1,982 men who reported using warfarin, aspirin, clopidogrel, enoxaparin, or a combination of the drugs. The primary outcomes were prostate cancer-specific mortality, disease recurrence (defined as biochemical failure or salvage therapy), and distant metastasis.
The anticoagulant group comprised 1,649 (83.2%) aspirin users, 428 (21.6%) warfarin users, 287 (14.5%) clopidogrel users, 26 (1.3%) enoxaparin users, and 408 (20.6%) users of more than one anticoagulant.
Patients on anticoagulants were slightly older (median of 66 versus 64, P<0.01), had longer follow-up (64 versus 56 months, P<0.01), had a slightly lower baseline PSA (6.0 versus 6.1 ng/mL, P<0.01), and were less likely to be treated surgically (62.4% versus 69.0%, P=0.03).
The risk of recurrence in the anticoagulation group was 22% at five years and 33% at 10 years, compared with 26% and 43% in the control group (P<0.01). The risk of distant metastasis increased from 1% at five years to 3% at 10 years in patients on anticoagulants versus 2% and 7% in the control group (P<0.01).
Prostate cancer-specific mortality in the anticoagulant group was 1% at seven years and 4% at 10 years versus 4% and 10% in the control group (P<0.01). Analysis by baseline clinical and tumor characteristics showed prostate cancer-specific mortality of 2% and 4% at seven and 10 years, respectively, among high-risk patients in the anticoagulant group compared with 8% and 22% in the control group (P<0.01).
Intermediate-risk patients also had a significant improvement in disease-specific survival (P=0.04), the researchers found.
The advantages of anticoagulant therapy were similar in patients treated with surgery or radiation therapy.
Analysis by type of anticoagulant showed that patients on aspirin alone had a prostate cancer-specific mortality of 1% at seven years and 2% at 10 years (P<0.01 versus control). Patients on aspirin and another anticoagulant had a prostate cancer-specific mortality of 0% at seven years and 5% at 10 years (P<0.01).
Use of another anticoagulant without aspirin was associated with a prostate cancer-specific mortality of 2% and 7% at seven and 10 years, respectively (P=0.06).
Choe and co-investigators stated that they had no relevant disclosures.
Primary source: American Society for Radiation Oncology
Source reference:
Choe KS, et al "Aspirin use and the risk of prostate cancer death in men treated with prostatectomy or radiotherapy: Results from the CaPSURE database" ASTRO 2010; Abstract 270.
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