**5. Anatomical vs. nonanatomical resection for HCC**

The incidence of HCC continues to increase due to the dissemination of hepatitis B and C virus infection. Hepatic resection is the gold standard treatment for HCC [74]. Nevertheless, postoperative recurrence of HCC, 3 and 5 years after hepatectomy is 50–60% and 70–90%, respectively [75, 76].

It is known that HCC invades mainly the intrahepatic vascular system and spreads along the portal and hepatic vein branches, producing intrahepatic metastases [77, 78].

Since Makuuchi et al. introduced the concept of anatomical resection (AR), the advantages of anatomic resection for HCC have been suggested in many studies [79]. On the other hand, limited nonanatomic resection (NR) with a minimal safety margin may be preferred for patients with impaired liver function [80]. Tanaka et al. showed that microscopic vascular invasion was more important than tumor size as a predictive factor for local recurrence [81].

Anatomical liver resection is a plausible option for patients with HCC, as HCC tends to cause intrahepatic metastasis through vascular invasion, and its advantages in improved OS or DFS for HCC patients have widely been reported [82].

In a systematic review of Cucchetti et al., AR seemed to yield improved 5-year OS and DFS compared to NR [83]. Zhou et al. [84] and Bigonzi et al. [85] presented significantly improved 5-year OS with AR.

Nonanatomic resection is recommended for patients with impaired liver function [86, 87]. The plausible reason is that NR can preserve as much functional liver as possible, with surgical curability and hepatic function equally important [87, 88]. The preservation of hepatic functional reserve allows effective treatment options in HCC recurrence, which may also improve the long-term prognosis [87, 89].

The superiority of anatomical resection (AR) over nonanatomic resection (NR) for hepatocellular carcinoma (HCC) remains controversial. Marubashi et al. reported no significant differences in OS, DFS or recurrence within 2 years after hepatectomy between the AR and NR groups [90]. Likewise, Tanaka et al. reported no outstanding difference in the recurrence rates and OS between AR and NR patient groups; it was also stated that survival rates after recurrence and median survival time after recurrence were higher in the NR group compared to the AR group for patients with a solitary HCC confined to 1 or 2 liver segments [91]. Chen et al. reported in their meta-analysis that AR contributed to better DFS, but did not improve OS [92]. Thus, the superiority of AR over NR is still controversial. Furthermore, Yamamoto et al. reported that AR is associated with more perioperative risks. The same study revealed significantly greater intraoperative blood loss and longer postoperative hospital stay for the AR group [82].

In 2010, Yamashita et al. [80] published a retrospective study of 321 patients with HCC. About 120 patients underwent limited nonanatomic resection (NR) for a single HCC < 5 cm. In noncirrhotic patients (n = 215), both 5-year OS and DFS rates in the AR group were considerably better than those in the NR group (87 vs. 76% and 63 vs. 35%, respectively). In cirrhotic patients (n = 106), both 5-year OS and DFS in the AR group were worse than those in the NR group (48 vs. 72% and 28 vs. 43%, respectively).

According to their results, the width of the resection margin did not influence postoperative recurrence, and major hepatic resections did not improve patients' survival. The main disadvantage of AR in comparison with NR is the limitation of a repeat resection, which would be the most effective treatment for recurrence, because of its disadvantageous effects on remnant liver function [93, 94].

In conclusion, there is a need for more, large, prospective, multicenter studies to confirm the data about any possible superiority of nonanatomic resection for HCC.
