Proposal of a new and simple staging system of colorectal liver metastasis

Table 1 Prognostic factors entered into multivariate analysis based on proposed clinical and histopathological features

Variable	Patients (n)
Gender (male/female)	61/20
Age at hepatectomy (< 60/≥ 60)	32/49
Chronology of hepatic metastasis (synchronous/metachronous)	41/40
Disease free interval after colectomy ( ≤ 1 yr/> 1 yr)	56/25
Extrahepatic distant metastases (no/yes)	72/9
CEA ( ≤ 10 times of normal value/> 10 times of normal value)	57/24
Primary lesion
Depth of invasion (up to subserosa/more)	57/24
Lymphnodemetastasi (no/yes)	39/42
Hepatic metastasis
Number (single/multiple)	45/36
Maximum diameter ( ≤ 5 cm/> 5 cm)	59/22
Lobe involved (unilobar/bilobar)	64/17

Table 2 Regression statistics for the stepwise cox proportional hazard model¹

Variable	Parameter	P	Hazard Ratio (95% CI)
Diameter > 5 cm	1.35657	0.0013	3.883 (1.703-8.852)
Extrahep. Met (+).	1.19430	0.0133	3.301 (1.282-8.502)
Number ≥ 2	0.85412	0.0265	2.349 (1.105-4.997)
D.F.interval < 1 yr	0.67838	0.1602	1.971 (0.765-5.080)
n (+) of primary	0.60034	0.1352	1.823 (0.829-4.007)
≥ se (+) of primary	0.54877	0.1676	1.731 (0.794-3.774)

¹Only those variables selected by the stepwise analysis, at the P-value of 0.20 level of significance, are shown. n = 81 (Tokyo Univ. 1981-1997). Age ≥ 60, gender, synchronous, bilobar invasion, CEA; P > 0.2.

Table 3 Our proposal staging system for colorectal liver metastases

Staging system
H-factor;
H1: Solitary&Diameter ≤ 5 cm
H2: Solitary&Diameter > 5 cm/Multiple&Diameter ≤ 5 cm
H3: Multiple&Diameter > 5 cm
M-factor;
M0: Extrahepatic metastasis (-)
M1: Extrahepatic metastasis (+): resectable
Staging;
I: H1&M0
II: H2&M0/H1&M1
III: H3&M0/H2&M1
IV: H3&M1
[IVb: any H & unresectable extraheptic metastasis (+)]