Major cancer surgery associated with ‘elevated’ risk for venous thromboembolism
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Key takeaways:
- Risk for venous thromboembolism persisted for up to 4 months after surgery.
- Absolute risk varied by cancer type but appeared least severe for patients who underwent surgery for breast cancer.
Patients who underwent cancer surgery had an increased risk for venous thromboembolism for up to 1 year after the procedure, results from a retrospective study published in JAMA Network Open showed.
However, certain risks for either pulmonary embolism or deep vein thrombosis varied by cancer type, according to study investigators.
“In this cohort study of postoperative venous thromboembolic events among patients who underwent cancer surgery, we found that the elevated relative risk [for] deep vein thrombosis and pulmonary embolism extends beyond an in-hospital or 28-day extended thromboprophylaxis,” Johan Björklund, MD, PhD, a member of the department of molecular medicine and surgery at Karolinska Institutet, and researchers wrote. “The 1-year postoperative risks [for] pulmonary embolism or deep vein thrombosis were different for different cancers, ranging from 0.57 to 4.67 percentage points, which should be considered in future prophylactic regimens.”
Background and methodology
The risks and benefits of thromboprophylaxis therapy following surgery for patients with cancer are not fully understood or researched, according to background information provided by the researchers.
Björklund and colleagues conducted a observational matched cohort study to evaluate the 1-year risk for venous thromboembolic events following major cancer surgery.
Researchers used registry data that include those among the population of Sweden who underwent major surgery for cancers of the bladder, breast, colon or rectum, gynecologic organs, kidney or upper urothelial tract, lung, prostate or gastroesophageal tract (n = 432,218; median age, 67 years; 68.7% women) between 1998 and 2016.
Study investigators matched those who received surgery in a 1:10 ratio with individuals without cancer in the general population (n = 4,009,343; median age, 66 years; 69.3% women).
Incidence of venous thromboembolic events within 1 year of surgery served as the study’s primary outcome; researchers calculated crude absolute risks and risk differences of events within 1 year.
Results, next steps
The analysis showed that the crude 1-year cumulative risk for pulmonary embolism appeared higher among patients who underwent major surgery for any cancer type than in the general population.
The differences in absolute risk by cancer type included: bladder cancer, 2.69 percentage points (95% CI, 2.33-3.05); breast cancer, 0.59 percentage points (95% CI, 0.55-0.63); colorectal cancer, 1.57 percentage points (95% CI, 1.5-1.65); gynecologic organ cancer, 1.32 percentage points (95% CI, 1.22-1.41); kidney and upper urinary tract cancer, 1.38 percentage points (95% CI, 1.21-1.55); lung cancer, 2.61 percentage points (95% CI, 2.34-2.89); gastroesophageal cancer, 2.13 percentage points (95% CI, 1.89-2.38); prostate cancer, 0.57 percentage points (95% CI, 0.49-0.66).
The cause-specific HR of pulmonary embolism between patients with cancer who underwent surgery and matched comparators of similar year of birth, sex and county of residence peaked following discharge from hospital and appeared to plateau 60 to 90 days later.
On day 30 after surgery, researchers noted the HR for pulmonary embolism to be 10 to 30 times higher than in the comparison cohort for all cancer types (colorectal cancer: HR = 9.18 [95% CI, 8.03-10.50]; lung cancer: HR = 25.66 [95% CI, 17.41-37.84]), except for breast cancer (HR = 5.18; 95% CI, 4.45-6.05).
They also reported similar results on risk for deep vein thrombosis.
The researchers noted certain study limitations, including a lack of information on treatments other than surgery received by patients with cancer that could potentially have increased risk for venous thromboembolism, as well as not taking into consideration potential changes in clinical practices or diagnostics that may impact occurrence and detection over the study period.
Björklund and colleagues said additional studies are needed to further understand the relationship between surgery for a specific cancer type and potential risk for venous thromboembolic events. The results, they added, highlight a need for raised attention and awareness to such events occurring within the first 90 to 120 days following surgery.
“Our observational data alone cannot, however, bring about a change in clinical practice, and future studies should evaluate individualized prophylactic regimens by taking the surgical trauma, disease severity, and exposure to systemic chemotherapy into account, to avoid both overtreatment and undertreatment in the prevention of venous thromboembolic events,” they wrote.
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