Background: Hypovascular tumors associated with hepatocellular carcinoma (HCC) can be diagnosed, but it remains unknown whether such lesions should be treated immediately. This study aimed to clarify the clinical significance of treating hypovascular liver nodules.
Methods: After diagnosis of hypovascular tumors smaller than 3 cm, 104 patients underwent liver resection immediately (Group 1), while 93 patients were placed under observation (Group 2). In Group 1, 98 patients were diagnosed as having HCC (Group 1'), while 80 patients in Group 2 underwent liver resection after vascularization or appearance of other hypervascular HCC (Group 2'), eight patients had been observed, and five patients could not undergo operation due to appearance of other multiple HCCs. To avoid lead time bias for tumor vascularization, survival rates of patients after diagnosis of hypovascular tumors as well as those after operation in the two groups were compared.
Results: After a median follow-up of 3.3 years (range 0.6-11.2), the 5-year overall survival rates after liver resection of Group 1' (74.8 %; 95 % CI 64.3-86.1) was significantly higher than that of Group 2' (59.2 %; 46.4-75.6; P = 0.027). However, the 5-year overall survival rates after diagnosis of hypovascular liver nodules of Group 1' (74.7 %; 66.1-85.0) was not significantly different from that of Group 2' (77.1 %; 67.0-88.6; P = 0.761). Consequently, the 5-year overall survival rate after diagnosis of Group 2 (75.6 %; 64.7-83.1) was not significantly different from that of Group 1 (73.2 %; 67.5-86.1; P = 0.591) by intention-to-treat analysis.
Conclusions: It is not necessary to treat hypovascular liver tumors immediately after diagnosis.