Although cancer patients have an increased risk for venous thromboembolism and an even higher risk during treatment, few oncologists take preventive measures, according to an article in the September 13th issue of the British Medical Journal.

The findings came from a survey of 106 oncologists in one region of England (with 106 representing 64 percent of the total to whom surveys were sent). The most common treatment was chemotherapy, used by 39 percent of oncologists, with hormone therapy used by 9 percent and radiotherapy by 42 percent.

A total of 29 physicians (27 percent) stated patients were not at risk for venous thromboembolism regardless of type of cancer. When asked if treatment affects risk, 71 (67 percent) stated hormone therapy posed little or no risk, 83 (78 percent) thought chemotherapy posed little or no risk, and 96 (91 percent) thought radiotherapy posed little or no risk.

In the article, the authors cited statistics about venous thromboembolism and breast cancer as an example of disease, treatment, and risk. A thromboembolic event occurs in 5 percent of patients on chemotherapy for early disease, with an event occurring in up to 18 percent of patients receiving chemotherapy for metastatic disease. Hormone therapy also increases risk: Patients with node-negative disease who take tamoxifen are six times more likely to have a thromboembolic event than women who are not on therapy.

Combinations of therapies increase risk above the level associated with any individual component. For instance, chemotherapy plus tamoxifen increases risk 3.5-fold compared with the risk for chemotherapy alone.

As another example of risk based on disease type and treatment, preoperative radiation therapy for rectal carcinoma doubles the risk for postoperative venous thrombosis.

The importance of recognition of action to prevent venous thromboembolism is seen in the findings from one recent study: Women on chemotherapy for metastatic breast cancer who received low-dose warfarin during treatment had a relative risk reduction of 85 percent without an increase in serious bleeding complications.

When the survey asked clinical practice, 84 (79 percent) said that they did not routinely use prophylaxis for patients receiving chemotherapy, 79 (75 percent) said they did not use prophylaxis with hormone therapy, and 86 (81 percent) said they didn’t use prophylaxis with radiation therapy. A total of 19 physicians (18 percent) stated they never used prophylactic measures against venous thromboembolism.

When asked what factors, if any, would prompt them to start prophylactic measures, 48 oncologists (45 percent) listed a history of previous venous thromboembolic event, 47 (44 percent) listed immobility, 25 (24 percent) listed thrombophilia, 18 (17 percent) listed a central venous line, and 16 (15 percent) listed obesity. Other responses were given by fewer than 10 of the 106 physicians who replied to the survey.

The authors concluded that, at least in Britain, clinical practice does not reflect the realities of the relations among cancer, treatment, and risk for venous thromboembolism; they urge an awareness campaign and practice guidelines for their country.