Roxanne Nelson

October 28, 2010

October 28, 2010 — Anticoagulant use in prostate cancer patients lowered disease-specific mortality by more than 50%, according to new data.

The findings were presented at a press briefing held in advance of the American Society for Radiation Oncology (ASTRO) 52nd Annual Meeting.

"The use of anticoagulants reduced the risk of dying from the disease to 4% from 10% at 10 years," said lead author Kevin Choe, MD, PhD, radiation oncologist at University of Texas Southwestern Medical School in Dallas.

The benefit was greatest with aspirin use over other anticoagulants, and benefits were most prominent in patients with high-risk disease, he said. "These are the patients we really need to treat and for whom current options are limited."

ASTRO president Anthony L. Zietman said that it has "long been suspected that good old boring inexpensive aspirin — that's been around for centuries — can in some way affect the ability of cancer cells to metastasize."

"There has been some evidence in colon cancer suggesting that this is true, but in prostate cancer, the data have gone both ways," said Dr. Zietman, who moderated the briefing.

Dr. Choe agreed. "It has been well known that there is a positive association between malignancy and the coagulation system," he said, pointing out that cancer patients appear to have a higher risk for thromboembolism, and individuals with a history of coagulation disorders have an increased cancer risk.

However, clinical data examining this association have led to conflicting results, and data are limited, he added.

At last year's ASTRO meeting, Dr. Choe presented data that demonstrated improved biochemical control of localized prostate cancer in men treated with radiation therapy who also used anticoagulants. As reported by Medscape Medical News at that time, the data showed that, at 4 years, the absence of biochemical relapse, measured by prostate-specific antigen (PSA) testing, was significantly better in the group of radiotherapy patients that received anticoagulants than in the group that did not (91% vs 78%; P = .0002).

Benefit Seen in Highest-Risk Group

In the current study, the benefit of anticoagulants was seen in men who had undergone radical prostatectomy or radiotherapy. Anticoagulants reduced the risk for disease-specific mortality, regardless of treatment mortality, explained Dr. Choe.

The study cohort consisted of 5295 men with localized adenocarcinoma of the prostate who underwent treatment with either radical prostatectomy (n = 3523) or radiotherapy (n = 1772). Within this group, 1982 (37%) were receiving anticoagulants that included warfarin (n = 428), clopidogrel (n = 287), enoxaparin (n = 26), aspirin (n = 1649), or a combination (n = 408) at the time of enrollment or during the follow-up period.

Median patient age was 65 years, and median PSA level was 6.0 ng/mL. Patients deemed low risk comprised 41% of the group, intermediate risk comprised 37%, and high risk comprised 21%. In addition, 28% of the patients had also received androgen-deprivation therapy. The primary end point of the study was the risk for disease-specific mortality.

Patients not using anticoagulants tended to be younger (median, 64 vs 66 years; P < .01), and were more commonly treated with radical prostatectomy (69% vs 62%; P < .01). Gleason score and clinical T stage were similar between the 2 groups.

The authors observed that at a median follow-up of 59 months, disease-specific mortality was significantly lower in patients who were using anticoagulants than in nonusers (1% vs 4% at 7 years and 4% vs 10% at 10 years; P < .01).

When analyzed by risk category, the reduction in mortality was most pronounced in those with high-risk disease (2% vs 8% at 7 years and 4% vs 22% at 10 years; P < .01). Further analysis by anticoagulant type suggested that the observed benefit was primarily fueled by aspirin use.

On multivariable analysis, the use of anticoagulants was independently associated with a lower risk for prostate-cancer-related mortality (adjusted hazard ratio, 0.53; P < .01), along with Gleason score, the use of radiation therapy combined with androgen-deprivation treatment, and statin use.

"This is another interesting and intriguing study and suggests future prospective studies that can be done," said Dr. Zietman.

The researchers have disclosed no relevant financial relationships.

American Society for Radiation Oncology (ASTRO) 52nd Annual Meeting: Abstract 270. To be presented November  3, 2010.

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