Background. Frailty has been globally recognized as a predictor of adverse postoperative outcomes. A frailty assessment using the five-factor modified frailty index (5-mFI) has recently gained traction; however, long-term outcomes are unknown in colorectal cancer (CRC) surgery. This study aimed to investigate whether the 5-mFI predicted long-term survival and cause of death based on severity of frailty in elderly patients with CRC surgery, as well as to determine risk factors for mortality.
Methods. A total of 299 patients underwent CRC surgery with curative intent between January 2013 and December 2017. Patients were divided into three groups based on 5-mFI score: group 1 (5-mFI: 0, 1; n=164) with no frailty, group 2 (5-mFI: 2; n=91) with moderate frailty, and group 3 (5-mFI≥3; n=44) with severe frailty. Clinicopathological variables, including comorbidity, 5-mFI, prognostic nutrition index, operative/postoperative data, and outcome, including cause of death, were compared among the three groups. To identify factors associated with death from CRC and non-CRC-related causes, univariate and multivariate analyses using the Cox regression model were performed.
Results. The immediate postoperative morbidity of patients with Clavien-Dindo grades of III or greater (9.1%) in group 3 was not significantly different from that in group 1 (9.1%) or group 2 (14.3%); however, the 30-day mortality rate (4.5%) in group 3 was significantly higher. Long-term disease-free survival was similar among frailty groups, suggesting that CRC surgery provides oncological benefit to patients irrespective of frailty. The 5-year survival rates in groups 1, 2, and 3 were 83.5%, 71.2%, and 47.9%, respectively, showing a significantly lower survival rate as frailty advanced. Sixty percent of deaths in frail patients were primarily from respiratory failure and cardiovascular diseases. Multivariate analysis demonstrated that advanced age, higher 5-mFI, and longer postoperative hospital stay were risk factors for mortality unrelated to CRC. Multivariate analysis also revealed that advanced tumor stage, CEA>5 ng/ml, undifferentiated tumor and R1 resection were risk factors for CRC death.
Conclusion. The 5-mFI can be a predictor of postoperative short- and long-term outcomes and risk factors for mortality unrelated to CRC. In addition, long-term survival was shown to be negatively associated with the 5-mFI score.