Presence of low titre of antiphospholipid antibodies in cancer patients: a prospective study.

Antiphospholipid antibodies (aPL) represent a well-defined risk factor for thrombotic events. aPL have been observed in the plasma of cancer patients, but the role and clinical relevance of aPL in this clinical setting is still unclear. This is a prospective cohort study whose aims were to: (1) compare the prevalence of aPL antibodies in cancer patients at diagnosis to matched control subjects; (2) compare thrombosis-free survival and overall survival in aPL positive and aPL negative cancer patients. One hundred and thirty-seven patients were enrolled upon a diagnosis of cancer, and were screened for lupus anticoagulant (LA), anticardiolipin antibodies, and anti-beta2 glycoprotein I antibodies (IgG and IgM). Two years of follow-up were scheduled. Low-titre aPL antibody positivity was found in 33 patients (24%), and in 6 controls (4.3%; P < 0.0001). During follow-up, nine patients developed a symptomatic, objectively confirmed, thromboembolic event. One thrombotic event was observed among the 33 aPL positive patients (3%), and 8 among the 104 aPL negative ones (7.6%) (P = NS). During follow-up, 21 patients died, and among them, 3 (9.1%) were aPL positive and 18 (17.3%) were aPL negative (P = 0.39; C.I. 0.28-0.05). In conclusion, a high prevalence of low-titre aPL was found in cancer patients at diagnosis, but no statistical difference in thrombosis-free survival or in overall survival was observed between aPL positive and aPL negative patients.