Occult cancer in patients with acute pulmonary embolism.

An association between venous thrombosis and cancer was first suggested by Trousseau, and has been confirmed by multiple postmortem studies. Clinical studies have shown that thrombophlebitis migrans may occur before malignancies become clinically evident, and therefore serves as a clue to occult cancer. A relation between occult cancer and the commoner deep venous thrombosis and pulmonary embolism has not been established. We ascertained the incidence of cancer before and after pulmonary embolism was diagnosed by pulmonary angiography in 128 patients. The incidence of cancer before pulmonary embolism (12%) was essentially the same as that in a comparison group of patients without pulmonary embolism (10%). In the 2 years after pulmonary angiography, however, cancer was diagnosed in 13 patients with pulmonary embolism in contrast to no patients in the comparison group (p less than 0.001). The most frequent cancers involved the lung, gastrointestinal tract, breast, and uterus. The malignancies were nearly always occult when pulmonary embolism occurred. These findings indicate that pulmonary embolism with or without overt deep venous thrombosis should alert the clinician to consider occult cancer.