The Decrease of Peripheral Blood Monocyte Count is a Possible Indicator for Neutropenia Due to Concurrent Chemoradiotherapy with TP Regimen in Nasopharyngeal and Cervical Cancer Patients

Abstract

Neutropenia is a major common side effect after concurrent chemoradiotherapy in cancer patients, leading to an increased risk of infection, an extended treatment period, and sometimes life-threatening events. Thus, it is extremely significant for clinicians to predict the timing of neutropenia following chemoradiotherapy, especially for outpatients. Both neutrophils and monocytes are differentiated from a common progenitor, a granulocyte macrophage colony forming cell, but no previous study clearly demonstrated the association between the change trend of the absolute monocyte count (AMC) and absolute neutrophil count (ANC) among patients undergoing concurrent chemoradiotherapy. The main objective of this study was to evaluate whether the decrease of peripheral blood AMC was a potential indicator to predict the occurrence of neutropenia. We retrospectively analyzed the medical records of consecutive nasopharyngeal and cervical cancer patients who underwent neutropenia following intensity-modulated radiation therapy (IMRT) and concurrent chemotherapy with paclitaxel liposome and cisplatin (TP) regimen between January 2017 and December 2018 at the Department of Radiotherapy & Oncology of our hospital. The chemotherapy doses were as followings: paclitaxel liposome 135 mg/m2 d1；cisplatin 25 mg/m2 d1-3, repeated every 21 days for two cycles. When peripheral blood ANC/AMC detected was first found to be below its baseline level at the first time, it was considered as the initial decrease, and the number of days after the first day of chemotherapy was calculated, respectively. When the ANC/AMC decreased to nadir point, it was considered as the minimal level, and the number of days after the first day of chemotherapy was also calculated, respectively. Similarly, when the ANC/AMC begin to increase from its nadir point, and following detection of the ANC/AMC would not decrease to below normal again, we called it the final increase and, respectively, calculated the number of days after the first day of chemotherapy. A paired sample t-test was used to assess whether the number of days when AMC initial decrease/are in nadir/final increase was significantly less than that of the ANCs. Seventy-seven patients (36 with nasopharyngeal cancer and 41 with cervical cancer) enrolled and analyzed finally. The change trend of AMC was consistent with that of ANC, and the number of days that AMC decreased/eventually increased to normal value was significantly less than that of ANC. The decrease of AMC was 5.43 days earlier than that of ANC count (95% CI of the difference: 4.51-6.34, p < 0.001), and the final increase of AMC was 6.0 days earlier than that of ANC (95% CI of the difference: 4.92-7.08, p < 0.001). The decrease of peripheral blood AMC is an important potential indicator to predict the occurrence of neutropenia and is also a significant indicator to guide the next monitoring time of ANC and the treatment of granulocyte colony stimulating factor.