Study: Future of Liver Surgery Is Minimally Invasive

Up to 70% of patients with colorectal liver metastasis are likely candidates for minimally invasive liver surgery (MILS) in high-volume centers, according to an Italian research group.

A single-center cohort study comparing outcomes in 885 resections for liver metastasis from colorectal cancer showed that even though survival rates were similar for the 698 patients who underwent open surgery compared with the 187 who underwent MILS, there was a significantly higher incidence of postoperative morbidity in open surgery patients — 94 (22.8%) versus 21 (20.2%); P=0.04.

“Oncologic results were not compromised by the laparoscopic approach,” Francesca Ratti, MD, of the Istituto Ricovero e Cura a Carattere Scientifico San Raffaele Hospital in Milan, and colleagues reported online in JAMA Surgery, a finding that confirms results from previous studies, the team noted.

“Since 2015, an estimated 60%-70% of patients in the present series have been suitable for a minimally invasive approach. A further increase of 15%-20% in the future is expected.”

Another 15%-20% of patients will never be suitable for laparoscopic surgery. Exclusion criteria “will always contraindicate minimally invasive surgery,” they pointed out.

The study also showed that patients in the MILS group had fewer major complications (Dindo-Clavien grades III-V) than patients in the open group — 94 (22.8%) versus 21 (20.2%), P=0.03 — and a shorter median hospital stay, of 3 versus 5 days (P=0.02).

After propensity score matching analysis, data comparison showed that median overall survival was 58 months in the open group versus 60 months in the MILS group (P=0.07). Median disease-free survival followed the same trend: 40 months in the open group versus 42 months in the MILS group (P=0.22).

Although 198 out of 412 patients (48.1%) in the open group had disease recurrence compared with 40 out of 104 patients (38.5%) in the MILS group (P=0.04), only the laparoscopic approaches favored additional surgery as the treatment of choice. This confirms “the superiority of MILS to allow further surgical treatment,” the study authors said.

“In the present series, laparoscopic surgery appeared to be effective in terms of oncologic validity expressed as resection margins, overall survival, and disease-free survival, giving overlapping results with open surgery outcomes. If a faster recovery was demonstrated as an independent variable, thus allowing patients an earlier return to chemotherapy, laparoscopy’s oncologic validity would be further supported.”

Learning Curve

Asked for his perspective, Rory L. Smoot, MD, of the Mayo Clinic in Rochester, Minn., who was not involved with the research, said that in the United States, more patients with colorectal liver metastasis will be offered minimally invasive procedures as more experience is gained in these procedures.

However, there is “a significant learning curve associated with minimally invasive major hepatectomy regardless of the disease process,” he cautioned. “Most centers will not be able to have multiple surgeons progress beyond the curve in a short period of time.”

Smoot pointed out that Ratti et al eliminated this learning curve from their study by comparing the most recent laparoscopic operations with the oldest open operations. “It is not a true comparison of what is happening as surgeons attempt to do more and more of these cases early on,” Smoot said.

In addition, the study’s rates for major complications and postoperative morbidity do not approach clinical or statistical significance for such a small sample size, he noted. “It is good that these studies continue to be done, but at best I believe the authors can claim that after attaining the learning curve, complication rates in their institution are equivalent to historical open controls.”

Study Details

For the study, the researchers looked at 885 resections for colorectal liver metastasis out of the 2,418 hepatic resections performed between January 2004 and June 2017.

Of the 104 patients in the MILS group, there were 46 women and 58 men, with a median age of 62. Patients in this group underwent 28 major resections (26.9%) and 76 minor ones (73.1%).

In the open surgery group, there were 412 patients, including 181 women and 231 men with a median age of 60. Patients in this group underwent 111 major resections (26.9%) and 301 minor resections (73.1%).

The investigators used time-dependent propensity score matching to compare the two groups. “Procedures performed using the MILS approach with a ratio of MILS to total resections per year of more than 30% were matched by propensity scores using a ratio of 1:4 to procedures performed using the open approach with a ratio of MILS to total resections per year of less than 30%.”

Although there was disease recurrence in a lower percentage of patients undergoing MILS, this finding may have been jeopardized by case selection prior to laparoscopy, the researchers said.

“It can also be speculated that long-term comparative outcomes of MILS and open resections are still hindered by the shorter follow-up time of laparoscopic series, while the effect of a more favorable biological scenario in minimally invasive surgery has yet to be investigated and should be the subject of future targeted investigations.”