The Comparison of Platelet-Derived Microparticles between Ambulatory Cancer Patients and Controls

Background:

Elevated levels of microparticles in cancer have been associated with hypercoagulability; however, the specific subtypes of microparticles are still unclear. We hypothesize that active cancer may increase the level of platelet-derived microparticles from platelet activation and play a role in cancer-associated thrombosis. Moreover, chemotherapy is also an important factor playing a role in platelet activation which may affect the levels of platelet-derived microparticles in ambulatory cancer patients.

Objectives:

To evaluate the hypothesis that platelet-derived microparticles will increase in cancer patients compared with non-cancer patients.

To extrapolate the hypothesis that levels of platelet-derived microparticles will increase after receiving chemotherapy.

Methods:

This was a prospective, cross-sectional study, where, we enrolled ambulatory cancer patients who were about to receive the first cycle (pre-chemotherapy) and those who already received a cycle of chemotherapy (post-chemotherapy). Controls were age- and sex- matched healthy individuals. Patients who had venous thrombosis or who were currently receiving anticoagulants were excluded. Flow cytometry was used to detect, quantify and specify platelet-derived microparticles using the co-expression of both Annexin V for phosphatidylserine and CD41a for platelet marker, and then reported as the unit of event/mL. All outcomes were compared among three groups.

Results:

A total of 45 patients and 15 controls were enrolled with a mean age of 58.09 years; of which, most patients were female. There was not any significant difference in age, sex, BMI, and platelet count among these groups. Gynecologic malignancy and lymphoma covered almost three-fourths of all patients, which were 51.11% and 24.44% of the total cancer patients, respectively. There was no significant difference in platelet-derived microparticles between cancer patients and controls [411,600 events/mL (331,200-722,400 events/mL) versus 563,640 events/mL (273,720-1,625,580 events/mL), p=0.3179].

Platelet-derived microparticles were significantly higher in cancer patients who had already received chemotherapy (post-chemotherapy) in comparison to cancer patients in the pre-chemotherapy group [582,000 events/mL (346,500-149,3220 events/mL) versus 402,300 events/mL (141,000 - 624,600 events/mL), p=0.0391], Figure 2. There was no significant difference in platelet-derived microparticles between hematologic and non-hematologic malignancy; however, the levels tend to be higher in the non-hematologic malignancy group.

Conclusions:

Platelet-derived microparticles were not significantly higher among cancer patients who have not received their first cycle of chemotherapy as compared to controls. However, after receiving chemotherapy, cancer patients exhibited significantly higher levels of platelet-derived microparticles. Chemotherapy is an important factor in platelet activation in cancer patients which may increase the levels of platelet-derived microparticles and play a role in cancer-associated thrombosis.