Study Links Thrombocytosis And Low Survivability In Ovarian Cancer Patients

Study Links Thrombocytosis And Low Survivability In Ovarian Cancer Patients

Researchers from the University Of Texas, MD Anderson Cancer Center suggest in a new study that survivability of ovarian cancer patients is reduced due to high levels of platelets in their blood. The new finding may lead to further progress in cancer treatment schemes.

“We’ve long known that ovarian cancer patients often have markedly increased platelet counts but we haven’t known why this happens or understood its relevance, if any, to disease progression”, said senior study author Anil Sood, M.D.

Scientists have discovered the cause of high platelet levels and the link between it and the severity of ovarian cancer, suggesting that anti-coagulant drugs might be introduced in ovarian cancer treatment schemes.

After analyzing clinical data from numerous ovarian cancer patients and after clinical trials conducted on laboratory rats, researchers from the University Of Texas discovered that ovarian tumors produce IL-6 (interleukin-6). This triggers an increase in TPO (or thrombopoietin, the hormone that stimulates platelet growth) synthesis in the liver, therefore causing an intense growth in platelet numbers, to more than 450,000 per cubic millimeter. The whole process further stimulates the growth of the tumor. Platelets were also found in ascites – a common sign in ovarian cancer, and even in the tumor bed.

Thrombocytes

A clinical trial held in London by the same research team also shows that patients treated with Siltuximab (a monoclonal antibody that binds to IL-6) had experienced a drop in platelet count.

An earlier search revealed an association between thrombocytosis and cancer, but a clear link between the two was never evidentiated. A clinical trial conducted on 619 patients revealed that almost 31 percent suffered from thrombocytosis whilst less than 2 percent suffered from iron deficiency, one of the main causes of high platelet levels. After taking tumor grade, patient age and disease stage into account, scientists discovered that high platelet levels continued to be a major factor in the poor survivability rate of patients.

Aside from breast cancer, researchers discovered that thrombocytosis can be found in pancreatic, uterine and epithelial ovarian cancer. A link between the effect of TPO, elevated levels of megakaryocytes (bone marrow cells that are responsible for producing thrombocytes) and high number of blood platelets has also been found.

A following clinical trial on 150 patients, and a subsequent trial on 310 patients revealed that patients with thrombocytosis have high levels of IL-6 and TPO in their blood. This analysis also shows that IL-6 can be associated with low survivability rates of ovarian cancer patients.

In order to find a solution to the problematic high levels of TPO and IL-6, scientists used short interfering RNA. Using laboratory rats they inhibited the action of IL-6 and TPO separately and together. In both cases, researchers managed to eliminate thrombocytosis.

Two strains of mice with induced ovarian cancer were further tested with Siltuximab, chemotherapy or both. These treatments all showed signs of reduced platelet count and tumor growth. The most effective treatment was the combination, showing a tumor growth reduction of almost 90 percent.

Scientists at the University Of Texas, MD Anderson Cancer Center will further continue their research to discover why exactly are platelets beneficial for tumor growth. The current study could be used to explain why certain cancer patients benefit from blood-thinning medication.

“If you see high platelets, absent inflammation or iron deficiency, it would be important to look for cancer”, noted Rebecca Stone, M.D., adding that high platelet levels may serve as a biomarker for some cancers.