Background: The relative growth rates of human liver metastases are not known. The aim of this study was to determine in humans the growth rate of liver parenchyma during regeneration and the growth rate of liver metastases during the same process.
Methods: Among 556 patients hepatectomized for a malignant lesion, 48 underwent preoperative selective right portal vein embolization to induce hypertrophy of the left lobe. Five cases were selected because a liver metastasis was present inside the regenerating left lobe. The volumes of the liver metastasis and left lobe were measured with a three-dimensional technique on pre-embolization and postembolization computed tomography (CT) or CT arterial portography. The median interval between the two measurements was 34 (range 28-40) days.
Results: An increase occurred in the volume of the liver metastasis and the left lobe in the four patients with functionally intact liver parenchyma, but not in the patient with an impaired parenchyma. The volumetric increase of the normal liver varied from 59 to 127 per cent, compared with 60 to 970 per cent for the liver metastases. The ratio between the growth rate of the left lobe and the liver metastasis varied from 1.0 to 15.6. The growth rates of two metastases in the left lobe of a single patient were different.
Conclusion: In functionally intact liver parenchyma, during hepatic regeneration or hypertrophy, the growth rate of metastases is more rapid that that of the liver parenchyma. However, a wide variation in growth rate is observed between patients and between metastases.