Efficacy of anatomic resection vs nonanatomic resection for small nodular hepatocellular carcinoma based on gross classification

Background/Purpose. It has been reported that anatomic resection may be preferable to nonanatomic resection for small hepatocellular carcinomas (HCCs), by reducing socalled "micrometastases" (portal venous tumor extension and intrahepatic metastases). Nonanatomic resection or ablation has also been used as therapy for small HCCs. We studied the effectiveness of anatomic resection for small nodular HCCs, especially from the viewpoints of tumor size and gross classification. Methods. A retrospective cohort study was performed in 116 consecutive patients who underwent curative hepatic resection for HCCs 3 cm or smaller and with three or fewer nodules. The outcome of anatomic resection (including segmentectomy, sectoriectomy, and hemihepatectomy) was compared to that of nonanatomic partial hepatectomy. Results. The group that underwent anatomic resection (n = 52) had relatively better overall survival and significantly better recurrence-free survival than those with nonanatomic resection (n = 64). On Cox multivariate analysis, however, liver function was more closely associated with survival. The effect of anatomic resection was more prominent in the subgroup with the nonboundary type nodules (single nodular type with extranodular growth, confluent multinodular type, and invasive type) than in the subgroup with the boundary type (vaguely nodular and single nodular type). Micrometastases in the nonboundary type were found further from the main tumor (9.5 +/- 6.2 mm) than those in the boundary type (within 3.1 +/- 1.4 mm). Conclusions. In patients with HCC nodules equal to or less than 3 cm and with the nonboundary type, anatomic resection should be employed to the extent that liver function allows, because this procedure would be more favorable than nonanatomic resection in eradicating micrometastases that have extended away from the tumor's margin.