Clarification of the correlation between recurrence-free survival and preoperative overall survival in patients after surgery for colorectal cancer liver metastases

A research group led by Masataka Ikeda, Professor in Chief of Department of Gastroenterological Surgery Division of Lower Gastrointestinal Surgery Hyogo Medical University (Location: Nishinomiya City, Hyogo Prefecture; President: Keiichiro Suzuki), has revealed a correlation between recurrence-free survival and pre-operative overall survival in patients following surgery for liver metastases from colorectal cancer.

Correlation between recurrence-free survival and overall survival after upfront surgery for resected colorectal liver metastases

Kozo Kataoka (※1), Kanae Takahashi (※2), Jiro Takeuchi (※3), Kazuma Ito (※1), Naohito Beppu (※1), WimCeelen (※4), Yukihide Kanemitsu (※5), Yoichi Ajioka (※6), Itaru Endo (※7), Kiyoshi Hasegawa (※8), Keiichi Takahashi (※9), Masataka Ikeda (※1)

(※1) Department of Gastroenterological Surgery Division of Lower Gastrointestinal Surgery, Hyogo Medical University of Medicine, (※2) Department of Medical Statistics, Hyogo Medical University of Medicine, (※3) Department of Clinical Epidemiology, Hyogo Medical University College of Medicine, (※4) Department of Gastroenterological Surgery, Ghent University (Belgium), (※5) Department of Colorectal Surgery, International Cancer Institute, Chuo University, (※6) Department of Clinical Pathology, Niigata University School of School of Medicine, (※7) Department of Gastroenterological and Oncological Surgery, Yokohama City University School of Medicine, (※8) Department of Hepato-Biliary-Pancreatic Surgery and Artificial Organ Transplant Surgery, The University of Tokyo, (※9) Department of Gastroenterological Surgery, Tokyo Metropolitan Okubo Hospital

An analysis of Japan's "nationwide database recording colorectal cancer liver metastases" revealed that "recurrence-free survival has a moderate correlation as an alternative indicator to overall survival" in patients after surgery for colorectal cancer liver metastases.

In patients who underwent surgery for colorectal cancer liver metastases, the correlation between the time to recurrence (recurrence-free survival: RFS) and overall survival (OS) was not fully understood. Therefore, the purpose of this study was to "find out the degree to which the two survival indicators, RFS and OS, correlate."

In this study, we extracted information on recurrence and survival for patients whose cancer had not metastasized outside the liver from the "Japan National Registry Database" of patients who underwent curative surgery for colorectal cancer, and calculated the correlation between RFS and OS. The correlation (ρ) between RFS and OS was calculated using rank correlation combined with repeated multiple imputation as an analytical method to take into account cases in which patient recurrence and survival information became unknown midway. In addition, as a secondary analysis, we also evaluated whether the content of chemotherapy administered after surgery had an effect on the correlation between RFS and OS.

The study included 2,385 patients with colorectal cancer liver metastasis from 2005-2007 and 2013-2014, and found a moderate correlation between RFS and OS (ρ = 0.73). In addition, it was found that the type of chemotherapy administered after surgery did not have a significant effect on the correlation between RFS and OS (oxaliplatin + 5-fluorouracil: ρ = 0.72; 5-fluorouracil alone: ρ = 0.72). This study has revealed "indicators for determining the future survival of patients" when colorectal cancer metastases to the liver and recurs after resection. With these indicators now known, doctors can use them to determine whether it is better to evaluate the patient's time to recurrence or their survival time when conducting clinical trials and evaluating new treatments.

We believe that further investigation is needed to determine to what extent recurrence-free survival time correlates accurately with overall survival time. As sufficient results have not yet been obtained, this "index for determining a patient's survival time" may change depending on the results of future clinical trials, etc.