Fewer Pulmonary Embolisms Seen in Cancer Patients With IVC Filters

By David Douglas

July 31, 2020

NEW YORK (Reuters Health) - Cancer patients who have inferior vena cava (IVC) filters face a lower risk of pulmonary embolism (PE) than do their peers without such filters, according to a new population-based study.

"Venous thromboembolism is a very common cause of morbidity and mortality in cancer patients," Dr. Rahul A. Sheth of the University of Texas MD Anderson Cancer Center, in Houston, Texas, told Reuters Health by email. "IVC filters are a commonly used device to prevent blood clots from the lower extremities (from spreading) to the lungs and cause a pulmonary embolism. However, the current data on the effectiveness of these devices for cancer patients are limited."

Dr. Sheth and colleagues used data collected between 2004 and 2014 in California and Florida to identify more than 88,000 patients with malignant neoplasms.

All patients had had hospital encounters involving a diagnosis of acute lower-extremity deep venous thrombosis (DVT). Of these patients, 33,740 (38.1%) underwent IVC-filter placement.

Among factors associated with significantly higher odds of filter placement were upper gastrointestinal bleeding, intracranial hemorrhage and coagulopathy.

Five percent of patients developed a new PE after their initial DVT diagnosis. Across the whole cohort there was a significant improvement in PE-free survival in patients who received a filter compared with those who did not. This was also the case after propensity-score matching and competing-risk analysis (hazard ratio, 0.69; P<0.001).

IVC-filter placement was also linked to a reduced risk of developing PE in such low-risk malignant neoplasms as prostate cancer, as well as high-risk and very high-risk malignant neoplasms such as lung cancer and pancreaticobiliary cancer.

"As with any intervention," say the researchers, "IVC filter placement is not without risk. Although the procedural technique is associated with low morbidity, the devices themselves can lead to complications."

Dr. Sheth said that in this study "of almost 90,000 cancer patients, we found that IVC filters reduced the risk for PE across the spectrum of cancer types. We also found that IVC filters did not increase the risk for lower-extremity blood clots."

In an accompanying editorial, Drs. J. Aaron Barnes and Philip P. Goodney of Dartmouth-Hitchcock Medical Center, in Lebanon, New Hampshire, note that unmeasured differences in the populations compared in the study "may harbor confounders in patient selection, and, as such, sicker patients may not have received filters if their survival appeared limited to the clinicians involved in their care."

Dr. Barnes added in an email to Reuters Health that "higher-quality studies, where the use of IVC filters was randomized, did not reflect (the new) findings. More work will be needed to clarify the role of IVC filters in high-risk patients."

SOURCE: https://bit.ly/2X4rh8L and https://bit.ly/2BGb3LM JAMA Network Open, online July 23, 2020.