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ANTICOAGULANTS USE INCREASE PROSTATE CANCER SURVIVAL

NEW YORK (Reuters Health) Feb 19 - Anticoagulant use may be a predictor of overall survival in men with metastatic castration-resistant prostate cancer (mCRPC) receiving docetaxel, retrospective data suggest.

The information, presented in a poster at the 2013 American Society of Clinical Oncology (ASCO) Genitourinary Cancer Symposium in Orlando, Florida, "adds to the growing body of evidence that anticoagulants, including aspirin although not studied here, improve outcome following treatment for prostate cancer," Dr. Mark Buyyounouski, from Fox Chase Cancer Center, Philadelphia, who moderated the poster session, told Reuters Health.

Presenting author Caroline Pratz, a nurse practitioner from the Johns Hopkins Sidney Kimmel Comprehensive Cancer Center in Baltimore, MD, told Reuters Health, "We had an interest in collecting data on these patients who had deep vein thrombosis or pulmonary embolism because we see them frequently in the clinic and we were curious as to how this would affect their overall survival."

Anticoagulants have been postulated to possess antitumor activity, although clinical data supporting this claim are conflicting, she said.

Pratz and her team reviewed the records of 247 consecutive mCRPC patients who received first-line docetaxel chemotherapy from 1998 through 2009, and noted whether anticoagulation was used and if so, the type, indication, and duration.

Twenty-nine men (11.7%) received anticoagulation; 15 for deep vein thrombosis (DVT), nine for pulmonary embolism (PE), and five for both DVT and PE.

Compared to men who received no anticoagulation, those who did had a significant increase in overall survival (hazard ratio for death 0.61; p=0.024). But when types of anticoagulants were analyzed separately, only low molecular weight (LMW) appeared to show a benefit (HR 0.58; p=0.048). The improvement with warfarin was not statistically significant (HR 0.82; p=0.23).

Patients who received any anticoagulant lived a median of 3.8 months longer (median overall survival 20.9 months with any anticoagulant versus 17.1 months with no anticoagulant).

After controlling for a number of other prognostic factors, including alkaline phosphatase, albumin, hemoglobin, prostate specific antigen, number of chemo cycles, and Eastern Cooperative Oncology Group status, anticoagulant use remained a significant predictor of overall survival (HR 0.63; p=0.038).

Pratz said she and her group were surprised by the study results. "It is counter-intuitive to what you think of when you think of blood clots. Typically they can be life threatening, so it was a surprise to us, although it has been reported in some other solid tumor cancers, that this was also the case."

Dr. Buyyounouski added: "These results are particularly compelling given the advanced nature of the disease in the study population."

"We've known for a long time that cancer and blood clots are related, that patients with cancer are more likely to have clotting and that patients with unexplained clotting disorders are more likely to get cancer. So in looking at whether using drugs that inhibit clotting will improve cancer outcomes Pratz and her group found that yes, it looks that way," he said.

Dr. Buyyounouski, a radiation oncologist, cautioned that the study is observational and sheds no light on the possible mechanism by which anticoagulation might benefit cancer outcomes.

"It may interfere with the cancer cells' ability to grow, that is one possibility. Another is that it perhaps interferes with the cancer's ability to stick in blood vessels, and this is one that people think is likely."

The ideal method of anticoagulation, dose, timing, and associated risks all need to be better defined and require further study, he added.

The 2013 Genitourinary Cancers Symposium is co-sponsored by the American Society of Clinical Oncology (ASCO), the American Society for Radiation Oncology (ASTRO), and the Society of Urologic Oncology (SUO).