“…A total of 36 studies were included, involving 11 143 subjects, composed of 6769 men and 4374 women. Of these studies, 19 were from Asia (Sasaki et al , 2005; Tanaka et al , 2008; Yi et al ., 2013; Lu et al ., 2016; Okimoto et al ., 2017; Peng et al ., 2017; Wang et al ., 2017; Zhang et al ., 2017; Kawahara et al , 2018; Miki et al ., 2018; Chiang et al ., 2019; Kim et al ., 2019; Chen et al ., 2020; Meng et al , 2021; Ishii et al ., 2022; Takamizawa et al ., 2022; Takeda et al ., 2022; Yoshino et al ., 2022; Li et al ., 2023), 11 from Europe (Hohenberger et al , 1994; Gervaz et al , 2000; Pawlik et al ., 2005; Arru et al ., 2008; John et al ., 2013; Montalti et al ., 2015; Hof et al , 2016; Imai et al ., 2016; Peltonen et al , 2018; Polivka et al ., 2020; Kamphues et al ., 2021), 4 from North America (Reddy et al , 2009a,b; Sasaki et al ., 2016; Masuda et al ., 2018), and one study each from Oceania (Niu et al , 2007) and South America (Dumarco et al ., 2023). A total of 31 studies discussed pre-LR CEA levels, and 9 studies investigated the effect of post-LR CEA levels on prognosis in CRCLM patients.…”