Summary
Venous thromboembolism (VTE) is a clinically important complication for both hospitalised
and ambulatory cancer patients. In the current study, the frequency, demographics
and risk (according to tumour site) of VTE were examined among patients seen at outpatient
DVT (deep-vein thrombosis) clinics. Of 10,015 VTE cases, 1,361 were diagnosed with
cancer, for an overall rate of cancer-associated VTE of 13.6% in this outpatient population.
Patients with cancer-associated VTE were significantly older than cancer-free VTE
cases (66.4 ± 12.7 vs. 58.8 ± 18.5 years; p<0.0001). The frequency of cancer-associated
VTE peaked earlier among females than males, occurring in the sixth (137/639, 21.4%
vs. 98/851, 11.3%; p<0.001) and seventh decades (213/980, 21.7% vs. 197/1096, 18%;
p=0.036). VTE was described most frequently in common cancers – breast, prostate,
colorectal and lung (56.1% of cases). The risk of VTE varied widely across 17 cancer
types. Calculating odds ratios (OR) to assess the effect size of cancer type on VTE
risk, the highest odds were observed for patients with pancreatic cancer (OR 9.65,
95% confidence interval [CI] (5.51–16.91). Tumours of the head and neck had higher
odds than previously reported (OR 8.24, 95% CI 5.06–13.42). Reduced risk estimates
were observed for skin cancers (melanoma and non-melanoma: OR 0.89, 95% CI 0.42–1.87;
OR 0.74, 95% CI, 0.32–1.69, respectively). We conclude that outpatients have a similar
rate of cancer-associated VTE as VTE patient populations previously reported, that
cancer-associated VTE occurs in an older age group and earlier in females and that
outpatients exhibit distinct tumour site-specific risk from that described among hospitalised
cancer patients.
Keywords
Clinical studies - cancer - venous thrombosis