Simultaneous colorectal and parenchymal-sparing liver resection for advanced colorectal carcinoma with synchronous liver metastases: Between conventional and mini-invasive approaches

Table 1 Controversial issues involving surgical strategies for colorectal cancer with synchronous resectable liver metastases

Controversial issue	Advantages	Disadvantages
Surgical strategies for synchronous CRLM:
• Traditional "staged" or "classic" approach	Risks of CRR and LR are not cumulated; CHT can be usefully administered before the LR	May determine progression of CRLM, sometimes up to unresectability; manipulation of metastatic CRC may have adverse effects on distant metastases and oncological outcome
• "Reverse" or "liver-first" approach	Avoids progression of borderline resectable CRLM; permits appropriate NACHRT for locally advanced rectal cancer, sometimes up to complete response	Comparative results with the traditional approach are still uncertain
• Simultaneous colorectal and liver resection	Reduces the number of surgical procedures; may reduce the duration of perioperative CHT; may decrease the cumulative costs of hospitalization	Requires accurate selection of candidates; may increase perioperative morbidity and mortality; oncological outcomes are still uncertain
NACHT of resectable CRLM	May reduce the extent of LR; may increase the R0 resection rates; eradicates micrometastases; may select patients with favourable oncological prognosis after LR	May determine progression of CRLM, sometimes up to unresectability; may determine parenchymal damage and increase perioperative morbidity; its overall beneficial impact on oncological outcomes has not been confirmed
Nonanatomic/parenchymal-sparing vs anatomic LR	May reduce the extent of LR; may increase resectability; may achieve better perioperative results; may favour reresection in case of hepatic recurrence, with consequent improvement of oncological results	May reduce the extent of the RM; its overall impact on oncological outcomes is still controversial
The prognostic role of the RM:
• ≥ 10 mm	May reduce the overall risk of recurrence; may achieve better oncological outcomes	May reduce resectability
• 1 to 10 mm	May reduce the extent of LR; may increase resectability	May favour tumour recurrence; may determine worse oncological outcomes
• < 1 mm (R1 resection)	May increase resectability	Determines worse oncological outcomes; perioperative CHT is mandatory
• “R1 vascular” RM (detachment of CRLM from vessels)	May reduce the extent of LR; may increase resectability	May favour tumour recurrence; may determine worse oncological outcomes
Evaluation of genetic mutations of CRLM	Predict response to CHT; may predict response to perioperative CHT; may predict oncological results of LR; may predict positive RM in candidates for LR; may suggest more extensive/anatomical LR; may predict response to local (RFTA) and loco-regional (chemo and radioembolization) treatments	Its overall role in establishing individualized therapeutic strategies is still uncertain; its overall impact on oncological outcomes is still uncertain
Treatment of multiple bilobar CRLM:
• NACHT of multiple resectable CRLM	May favour curative LR; may reduce the extent of LR; may increase the R0 resection rates; eradicates micrometastases; may select patients with favourable oncological prognosis after LR	May determine progression of CRLM, sometimes up to unresectability; may determine parenchymal damage and increase perioperative morbidity; its overall beneficial impact on oncological outcomes is uncertain
• PSLR vs major LR, including PVE, TSH and ALPPS	Reduces the extent of LR; may increase resectability; reduces the risk of PHLF; may achieve better perioperative results; may favour reresection in case of hepatic recurrence	May reduce the extent of the RM; its overall impact on oncological outcomes is still controversial
• Intraoperative local ablation techniques	May reduce the extent of LR; may increase resectability; may favour curative LR	Higher risk of local recurrence, especially for larger tumours; its overall beneficial impact on oncological outcomes is still uncertain
The impact of PSLR on simultaneous resections	May reduce the extent of LR; may increase resectability of CRLM; may improve the propensity for simultaneous resection; may achieve better perioperative results	May reduce the extent of the RM of LR; its overall impact on oncological outcomes is still controversial

CRLM: Colorectal liver metastases; CRR: Colorectal resection; LR: Liver resection; CHT: Chemotherapy; CRC: Colorectal cancer; NACHRT: Neoadjuvant chemoradiotherapy; RM: Resection margin; RFTA: Radiofrequency thermal ablation; NACHT: Neoadjuvant CHT; PSLR: Parenchymal-sparing liver resection; PVE: Portal vein embolization; TSH: Two-stage hepatectomy; ALPPS: Associating liver partition and portal vein ligation for staged hepatectomy; PHLF: Posthepatectomy liver failure.

Table 2 Controversial issues involving mini-invasive (laparoscopic and robotic) surgical strategies for colorectal cancer with synchronous resectable liver metastases

Controversial issue	Advantages	Disadvantages
Mini-invasive vs open colorectal surgery	Achieves better perioperative results; achieves similar oncological results	In case of rectal resection, may determine a higher risk of suboptimal oncological results at histopathology; in case of rectal resection, its overall impact on oncological outcomes is still uncertain
Mini-invasive vs open liver surgery	Achieves better perioperative results; achieves at least similar oncological results; rapid technological evolution; rapid growth of surgical experience and skill	Usually preferred for limited disease, in favourable locations and selected patients; may determine more complex and longer procedures; may determine more extended hepatectomies; less frequently used for major LR, including TSH and ALPPS, and for CRLM in postero-superior segments and in the caudate lobe; may determine higher costs
Mini-invasive vs open simultaneous colorectal and liver resection	Achieves better perioperative results; achieves similar oncological results	Usually preferred for limited liver disease, in favourable locations, and higly selected patients; may determine more complex and longer procedures; may determine higher costs
Mini-invasive vs open PSLR	Achieves better perioperative results; achieves similar oncological results; rapid technological evolution; rapid growth of surgical experience and skill	The principles of PSLR are time-consuming and rather difficult to apply during mini-invasive procedures; usually preferred for limited disease, in favourable locations and selected patients; may determine more complex and longer procedures; may determine higher costs
The impact of PSLR on mini-invasive simultaneous resection	May achieve better perioperative results; may achieve similar oncological results	May determine more complex and longer procedures; may have very limited indications

LR: Liver resection; TSH: Two-stage hepatectomy; ALPPS: Associating liver partition and portal vein ligation for staged hepatectomy; CRLM: Colorectal liver metastases; PSLR: Parenchymal-sparing liver resection.