Leukocyte kinetics during the first cycle of chemotherapy predicts the outcome of patients with metastatic colorectal cancer and previous resection of the primary tumor.

BACKGROUND: Many reports suggest more activity of cytotoxic chemotherapy among patients with metastatic colorectal cancer (mCRC) who experience neutropenia, but it is not clear whether this finding is related to drug effect alone. The aim of the study is to identify the characteristics of patients whose peripheral blood cell kinetics (PBCK) is related to the outcome. METHODS: The study is a retrospective analysis of patients with mCRC who had received first-line chemotherapy at Sanremo hospital from 2010 to 2015, evaluating seventeen baseline variables, six related to systemic inflammatory response activation (SIRA), and six to peripheral blood cell kinetics after one cycle. The relationship of peripheral blood cell kinetics variables was evaluated by tumor location, SIRA, and timing of metastases. RESULTS: Among 203 eligible patients, only four variables were able to independently predict survival (age, CA 19-9, number of drugs, chemotherapy-induced leukopenia after the first cycle or CIL-1). After stratification by tumor location or by SIRA, no relationship of PBCK variables with prognosis was present. On the contrary, after stratification by timing of metastasis, the prognostic role of CIL-1 was evident among patients with metachronous metastases, particularly among those with low SIRA and colon tumors, whereas the leukocyte reduction after the first cycle (WR) predicted longer survival of patients with synchronous metastases and a previous resection of the primary tumor (PTR). CONCLUSIONS: Absolute leukocyte reduction (CIL-1) predicts a better OS of patients with metachronous metastases, whereas relative leukocyte reduction (WR) could be prognostic among patients with synchronous metastases who have received PTR.