Paraneoplastic thrombocytosis in breast cancer.

BACKGROUND Elevated platelet count at the time of diagnosis has been suggested to identify a subset of patients with cancer (e.g. ovarian and lung adenocarcinoma) and poor prognosis. The evidence on the incidence and prognostic significance of thrombocytosis in breast cancer is, however, incomplete. PATIENTS AND METHODS We performed a retrospective analysis of 127 consecutive patients with breast cancer at our Institution. RESULTS None of the 81 newly- diagnosed patients had an elevated platelet count (mean=252 × 10(6)/l). Out of the 31 patients with metastatic disease, one exhibited mild thrombocytosis (445 × 10(6)/l) but the mean value (239 × 10(6)/l) was similar to that seen in patients with localized disease. CONCLUSION We conclude that thrombocytosis in breast cancer is rare and thus, unlike in other types of cancer, and has limited (if any) value in clinical decision making.