Sex Differences in Patients With Occult Cancer After Venous Thromboembolism

In patients with venous thromboembolism (VTE), male sex has been associated with an increased risk of occult cancer. The influence of sex on clinical characteristics, treatment, cancer sites, and outcome has not been thoroughly investigated yet. We used the Registro Informatizado Enfermedad TromboEmbólica registry to compare the clinical characteristics, treatment strategies, cancer sites, and clinical outcomes in patients with VTE having occult cancer, according to sex. As of June 2014, 5864 patients were recruited, of whom 444 (7.6%; 95% confidence interval: 6.8-8.2) had occult cancer. Of these, 246 (55%) were men. Median time elapsed from VTE to occult cancer was 4 months (interquartile range: 2-8.4), with no sex differences. Women were older, weighed less, and were less likely to have chronic lung disease than men. The most common cancer sites were the lung (n = 63), prostate (n = 42), and colorectal (n = 29) in men and colorectal (n = 38), breast (n = 23), uterine (n = 18), hematologic (n = 17), or pancreas (n = 15) in women. Men were more likely to have lung cancer than women (2.18% vs 0.30%; P <.01) and less likely to have pancreatic cancer (0.17% vs 0.5%; P =.03). Interestingly, breast cancer was more likely found in women aged ≥50 years than in those aged <50 years (0.97% vs 0.14%; P =.03). This study highlights the existence of sex differences in patients with VTE having occult cancer. One in every 2 men had lung, prostate, or colorectal cancer. In women, there is a heterogeneity of cancer sites, increasing risk of breast cancer in those aged >50 years.