Prognostic Significance of Immune Thrombocytopenic Purpura In Patients with Malignancy.

Abstract 1428

Immune thrombocytopenic purpura (ITP) occurs in a few patients with malignancies such as breast, gastric, lung, cervical, ovarian cancers, and hematologic malignancies. The existence of ITP in these malignancies often has been regarded as a poor prognostic factor. However, recent researchers suggest that platelets have significant roles in cancer metastasis by promoting angiogenesis, maintaining vascular integrity and protecting tumor cells from NK cells. Therefore, low platelet counts might influence on the outcome the associated malignancies. This study was performed to get the clinical information whether malignancies accompanying ITP have poor outcome or not.

A total of 18 patients with malignancies diagnosed as ITP at the National Cancer Center in Korea between 2000 and 2010 were included. The diagnosis of ITP was confirmed when their platelet counts were less than 140,000/mm³ after exclusion of other causes of thrombocytopenia. No one had an evidence of disseminated intravascular coagulation at the time of ITP diagnosis and 14 patients had been examined for bone marrow biopsy to rule out other diseases than ITP.

Of the 18 patients included in this study, 7 patients were men and 11 patients were women with median age 59 years (range, 40 to 79 years). The most common cancer was the gastric cancer (n=5). Colorectal cancers (n=4), breast cancers (n=3), lung, pancreas, thyroid, ovarian, endometrial cancer and acute myeloid leukemia were examined. ITP was diagnosed concomitantly in 3 cases and after detection of malignancies in 15 cases with a median interval 8.5 months (range, 1 to 75 months). All of gastric cancer patients had Helicobacter pylori (H. pylori) infection detected by H. pylori IgG or stomach biopsy methods. The other 3 out of 13 patients (23%) showed H. pylori infection by the same methods. Of the 16 patients checked for anti-platelet antibody, only 2 (13%) patients revealed positive results. No one showed anti-HCV antibody.

Six patients (30%) died of disease progression. Two patients (10%) are alive with residual disease and 10 patients (60%) are alive in disease-free statuses. Except 2 patients, no one had distant metastatic lesions at the initial diagnosis of cancer. At the time of malignancy diagnosis, there were 2 patients with distant metastasis and 5 patients at the time of last follow-up. Two gastric cancer patients who are alive in advanced stages (stage III, 43 months; stage IV 5.7 months) have survived similar or more than expected in the report (Park JM et al, Gastrointest Cancer Res 2009). A colorectal cancer patient with prostate cancer has survived 67 months. Another patient who died of stage IV colon cancer survived 19 months which was comparable to the report of the same stage colorectal cancer with median survival of 18 months in Korea (Park YJ et al, World J Surg 1999). ITP was stable in 8 patients without treatment. Nine patients received corticosteroid or immunoglobulin therapy. Anti-D immunoglobulin was administered to 2 patients who had been refractory to corticosteroid and immunoglobulin. Splenectomy was performed 3 patients who were not responsive to medical treatment and showed clinical improvement. There were only 2 patients who had shown platelet count increase after treatment of malignancies.

ITP associated with malignancies were stable and responsive to therapy in this study. Although there was a limitation of interpretation due to the heterogeneity of this study group, clinical outcomes of the cancer patients with ITP did not show poor prognosis. Especially, rare patients showed distant metastasis during the disease course. Further experimental and clinical studies are needed to investigate the relationship between platelet and tumor progression including metastasis.