UroToday.com – Prostate cancer is the most common cancer among men, especially in elderly men. Since these men often also have cardiovascular diseases that require anticoagulation therapy, it is not uncommon for prostate cancer patients to be on anticoagulants, such as Coumadin and Plavix.

External beam radiotherapy is one of the standard treatment options for localized prostate cancer, and it may be the preferred choice for older patients with significant comorbid illnesses. Despite the tremendous advances in delivery of radiation recently, rectal bleeding remains a common and potentially serious toxicity of radiation. We investigated the prevalence and severity of bleeding toxicity from prostate cancer radiotherapy among patients who are on Coumadin or Plavix.

As expected, the use of Coumadin or Plavix led to a significant increase in Grade 3 or 4 bleeding toxicity after radiotherapy. The 4-year risk of serious bleeding toxicity was 16% in patients on anticoagulants, compared to less than 4% in the other patients not on any anticoagulants. On multivariate analysis, use of anticoagulants was the only significant variable associated with serious bleeding. Among the patients on anticoagulants, higher dose of radiation and previous TURP were associated with bleeding toxicity.

Interestingly, intensity-modulated radiotherapy (IMRT), which usually allows more conformal radiation delivery and sparing of more normal tissue, was associated with worse bleeding toxicity. While IMRT generally limits the amount of normal tissue exposed to high doses of radiation, it can lead to small areas receiving higher maximal dose. In other words, hot spots can be hotter, especially with certain radiation optimizing algorithms. With more recent treatment planning software, this drawback may be mitigated.

Due to the substantial risk of serious bleeding, caution must be exercised when treating patients on anticoagulation with radiation. It warrants special consideration when determining the optimal radiation dose, target volume, and limiting dose constraints. With further advancement of radiation therapy, including high-precision stereotactic radiotherapy and real-time target localization, we may be able to deliver radiation more safely to patients on anticoagulation. Furthermore, in place of external beam radiotherapy, prostate brachytherapy with radioactive seeds may reduce the amount of rectum exposed to high doses of radiation and may represent another important treatment option for these patients.

Written by Kevin S. Choe, MD, PhD as part of Beyond the Abstract on UroToday.com

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