Author: Salynn Boyles, Contributing Writer, MedPage Today
Clinically relevant blood clots are common in head and neck cancer patients following surgery, and routine chemoproprophylaxis is warranted in post-surgical patients hospitalized for more than 72 hours, a prospective study has found.
When the researchers followed 100 high-risk cancer patients for 30 days following surgery, they found that 13% developed venous thromboembolism (VTE), including seven who had deep vein thrombosis (DVT) and one with pulmonary embolism (PE).
A total of 14% of the patients received postoperative anticoagulation therapy, and their rate of bleeding complications was 30% compared with 5.6% in patients who did not receive the therapy (P=0.01), Daniel R. Clayburgh, MD, PhD, of Oregon Health and Science University in Portland, and colleagues wrote online Sept. 26 in JAMA Otolaryngology-Head and Neck Surgery.
While the study was not powered to detect differences in risk factors among patients who did and did not develop VTEs, there was a trend in those with VTEs toward lower mean Karnofsky-Performance status scores (72 versus 79 in patients without them; P=0.09) and higher Caprini risk assessment scores (7.6 in VTE patients vs 6.9 in those who did not develop blood clots; P=0.09). These risk factors did not reach statistical significance.
The VTE incidence reported by Clayburgh and colleagues was higher than has been suggested in retrospective studies of the general otolaryngology population, with one recent study finding an overall VTE rate of just 1.3%.
The incidence is also higher than the OHSU research team’s own 2012 retrospective analysis of VTE in high-risk surgical patients with head and neck cancer, which confirmed VTE in 1.4% of patients. Just under 6% of patients in the study had confirmed or suspected VTE.
Cancer patients are considered a high-risk group for developing post-surgical VTE, and many medical groups including the American College of Chest Physicians and the American Society of Clinical Oncology recommend VTE prophylaxis in patients with cancer for at least a month post-surgery.
But because the VTE rate has been thought to be low in the otolaryngology population and because complications from anticoagulation therapy can be life-threatening, head and neck surgeons often ignore these guidelines, Clayburgh and colleagues noted.
“Compliance with VTE guidelines has historically been poor among otolaryngologists, presumably because patients are often able to ambulate soon after surgery, and the potential consequences of airway compromise from bleeding or hematoma are catastrophic,” they wrote. “Furthermore, there is relatively little data supporting the use of routine postoperative anticoagulation in head and neck surgery patients.”
The newly published study represents one of the first prospective examinations of the incidence of VTE in head and neck cancer surgery patients.
The 100 patients included in the study all had surgery to treat head and neck cancer at a tertiary care academic surgical center.
Between 2 and 3 days following surgery, clinical examinations and duplex ultrasonographic evaluations (US) were performed on all patients. Those with evidence of DVT or PE received anticoagulation therapy, while those with superficial VTE underwent repeat US on post-operative day four, five, or six.
Of the 13 patients that developed VTEs, nine had no clinically evident symptoms associated with the event. One experienced leg swelling, one had shortness of breath, one experienced arm swelling and discomfort and one had upper extremity swelling (4% overall rate of symptomatic VTE).
“The substantial number of asymptomatic VTEs found on routine postoperative duplex ultrasonography suggests that the incidence of VTE may have been underestimated in previous retrospective studies,” the researchers wrote.
Neither patient age, BMI, Charlson comorbidity Index score, preoperative D-dimer, or time-to-ambulation were predictive of VTE occurrence, but five of 15 patients (33%) with Caprini scores greater than 8 developed VTE, compared to just 8 of 85 (9%) of patients with scores of 8 or lower (P=0.02).
Study limitations cited by the researchers included a potential confounding effect related to the use of VTE chemoprophylaxis in some patients. They noted that most of the patients who were treated with VTE chemoprophylaxis had been admitted to the ICU following surgery and were treated according to standardized ICU protocols.
“It could be argued that excluding these participants would exclude the sickest participants who are potentially at greatest risk for VTE,” they wrote. “Thus, we elected to include all participants as an intention-to-treat analysis despite the potential confounding effects of the use of VTE chemoprophylaxis.”
They added that the study population was highly selected to include only high-risk patients so the results can not be extrapolated to those with early-stage, limited head and neck cancer.
Despite these limitations, Clayburgh and colleagues concluded that post-surgical VTE appears to occur at a higher rate than has previously been reported in high-risk head and neck cancer patients.
“Our results support the use of routine VTE chemoprophylaxis in patients with head and neck cancer admitted for more than 72 hours after surgery,” they wrote. “Importantly, these data establish a baseline VTE rate in high-risk head and neck cancer surgery patients that can serve as a benchmark for future prospective trials of VTE chemoprophylaxis and risk stratification.”