{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,28]],"date-time":"2026-01-28T05:06:59Z","timestamp":1769576819250,"version":"3.49.0"},"reference-count":48,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,1,27]],"date-time":"2026-01-27T00:00:00Z","timestamp":1769472000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Cancers"],"abstract":"<jats:p>Introduction: Operative time is commonly used as a surrogate marker for operative difficulty in liver resection, but the contribution of other intraoperative factors is less understood. This study aimed to develop an objective, composite score to assess operative difficulty and evaluate its association with postoperative and oncological outcomes in liver surgery. Methods: A retrospective cohort study was conducted on patients who underwent liver resection for malignant disease between 1999 and 2023 at an Australian tertiary hospital, using a prospectively maintained database. Principal component analysis (PCA) was applied to operative time, estimated blood loss, total time of hepatic inflow occlusion and the number of packed red bloods transfused intraoperatively to derive a composite operative difficulty score. Patients were then stratified into low, moderate and high difficult groups using Gaussian mixture models (GMM). Comparison of textbook oncological outcomes (TOO) achievement and futile resection rates were assessed using Chi-squared analysis. Kaplan-Meier analysis was used to assess recurrence-free and overall survival in subgroup analysis. Results: Of 729 patients, 699 met the inclusion criteria. GMM identified three distinct operative difficulty groups: low (n = 540), moderate (n = 143), and high (n = 16). TOO and non-futile resection rates declined with increasing difficulty: 77% and 58% (low), 47% and 52% (moderate), and 6% and 19% (high), respectively (p &lt; 0.001, p = 0.004 respectively). Among patients with cholangiocarcinoma, median overall survival was inversely correlated with operative difficulty (40 months low, 16 months moderate, 7 months high, p = 0.004). In patients with colorectal liver metastases, there was a trend towards worse overall survival and disease-free survival with increasing operative difficulty, however, this did not reach statistical significance. Conclusions: An objective intraoperative difficulty score was developed and demonstrated a significant inverse association with both quality and oncological outcomes. While external validation is required, these findings support the potential of operative difficulty assessment to enhance perioperative decision-making, inform patient counselling, and optimise postoperative care planning.<\/jats:p>","DOI":"10.3390\/cancers18030407","type":"journal-article","created":{"date-parts":[[2026,1,27]],"date-time":"2026-01-27T15:41:56Z","timestamp":1769528516000},"page":"407","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Decoding Surgical Complexity: Measuring the Impact of Operative Difficulty on Quality Outcomes Following Hepatectomy for Liver Cancer over Two Decades"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1039-902X","authenticated-orcid":false,"given":"Meet","family":"Patel","sequence":"first","affiliation":[{"name":"Faculty of Medicine and Health, The University of Sydney, Science Rd, Sydney, NSW 2050, Australia"},{"name":"Concord Repatriation General Hospital, Sydney, NSW 2139, Australia"},{"name":"Northern Clinical School, The University of Sydney, Sydney, NSW 2050, Australia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0003-2182-6274","authenticated-orcid":false,"given":"Jonathan Ben","family":"Daniel","sequence":"additional","affiliation":[{"name":"Faculty of Medicine and Health, The University of Sydney, Science Rd, Sydney, NSW 2050, Australia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3995-4285","authenticated-orcid":false,"given":"Nazim","family":"Bhimani","sequence":"additional","affiliation":[{"name":"Faculty of Medicine and Health, The University of Sydney, Science Rd, Sydney, NSW 2050, Australia"},{"name":"Upper Gastrointestinal Surgical Unit, Royal North Shore Hospital, Sydney, NSW 2065, Australia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0762-0977","authenticated-orcid":false,"given":"Anthony R.","family":"Glover","sequence":"additional","affiliation":[{"name":"Faculty of Medicine and Health, The University of Sydney, Science Rd, Sydney, NSW 2050, Australia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Thomas J.","family":"Hugh","sequence":"additional","affiliation":[{"name":"Faculty of Medicine and Health, The University of Sydney, Science Rd, Sydney, NSW 2050, Australia"},{"name":"Northern Clinical School, The University of Sydney, Sydney, NSW 2050, Australia"},{"name":"Upper Gastrointestinal Surgical Unit, Royal North Shore Hospital, Sydney, NSW 2065, Australia"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,1,27]]},"reference":[{"key":"ref_1","first-page":"229","article-title":"Global cancer statistics 2022: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries","volume":"74","author":"Bray","year":"2024","journal-title":"CA Cancer J. Clin."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1273","DOI":"10.21037\/tcr-20-3319","article-title":"Incidence and survival outcomes of secondary liver cancer: A Surveillance Epidemiology and End Results database analysis","volume":"10","author":"Wang","year":"2021","journal-title":"Transl. Cancer Res."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"7887","DOI":"10.3748\/wjg.v20.i24.7887","article-title":"Indications, limitations and maneuvers to enable extended hepatectomy: Current trends","volume":"20","author":"Dimitroulis","year":"2014","journal-title":"World J. Gastroenterol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"332","DOI":"10.1016\/j.jamcollsurg.2016.03.039","article-title":"Completion of a Liver Surgery Complexity Score and Classification Based on an International Survey of Experts","volume":"223","author":"Lee","year":"2016","journal-title":"J. Am. Coll. Surg."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1097\/SLA.0000000000002176","article-title":"Difficulty of Laparoscopic Liver Resection: Proposal for a New Classification","volume":"267","author":"Kawaguchi","year":"2018","journal-title":"Ann. Surg."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"333","DOI":"10.1016\/S1365-182X(17)30755-4","article-title":"The Brisbane 2000 Terminology of Liver Anatomy and Resections","volume":"2","author":"Strasberg","year":"2000","journal-title":"HPB"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"805","DOI":"10.1097\/SLA.0000000000005133","article-title":"Predicting Intraoperative Difficulty of Open Liver Resections: The DIFF-scOR Study, An Analysis of 1393 Consecutive Hepatectomies From a French Multicenter Cohort","volume":"274","author":"Pothet","year":"2021","journal-title":"Ann. Surg."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1007\/s13304-015-0302-7","article-title":"The difficulty of laparoscopic liver resection","volume":"67","author":"Ban","year":"2015","journal-title":"Updates Surg."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1182","DOI":"10.1002\/bjs.10821","article-title":"Development and validation of a difficulty score to predict intraoperative complications during laparoscopic liver resection","volume":"105","author":"Halls","year":"2018","journal-title":"Br. J. Surg."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"5356","DOI":"10.1007\/s00464-017-5616-8","article-title":"A novel model for prediction of pure laparoscopic liver resection surgical difficulty","volume":"31","author":"Hasegawa","year":"2017","journal-title":"Surg. Endosc."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"519","DOI":"10.1089\/lap.2025.0041","article-title":"Navigating Complexity in Liver Resection: A Narrative Review of Factors Influencing Intraoperative Difficulty","volume":"35","author":"Patel","year":"2025","journal-title":"J. Laparoendosc. Adv. Surg. Tech. A"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"12","DOI":"10.1016\/j.annemergmed.2022.01.046","article-title":"Composite Outcomes in Clinical Prediction Modeling: Are We Trying to Predict Apples and Oranges?","volume":"80","author":"Dash","year":"2022","journal-title":"Ann. Emerg. Med."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"923","DOI":"10.1097\/SLA.0000000000000961","article-title":"\u201cSurgeons\u2019 intuition\u201d versus \u201cprognostic models\u201d: Predicting the risk of liver resections","volume":"260","author":"Farges","year":"2014","journal-title":"Ann. Surg."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2602","DOI":"10.1245\/s10434-015-5058-2","article-title":"Defining Surgical Difficulty According to the Perceived Complexity of Liver Resection: Validation of a Complexity Classification in Patients with Hepatocellular Carcinoma","volume":"23","author":"Muangkaew","year":"2016","journal-title":"Ann. Surg. Oncol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"881","DOI":"10.1007\/s13304-023-01452-4","article-title":"The difficulty grade of laparoscopic hepatectomy for hepatocellular carcinoma correlates with long-term outcomes","volume":"75","author":"Lv","year":"2023","journal-title":"Updates Surg."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"3732","DOI":"10.1007\/s00464-021-08687-5","article-title":"External validation of different difficulty scoring systems of laparoscopic liver resection for hepatocellular carcinoma","volume":"36","author":"Lin","year":"2022","journal-title":"Surg. Endosc."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"12","DOI":"10.1089\/lap.2018.0150","article-title":"Clinical Practicality Study of the Difficulty Scoring Systems DSS-B and DSS-ER in Laparoscopic Liver Resection","volume":"29","author":"Yang","year":"2019","journal-title":"J. Laparoendosc. Adv. Surg. Tech. A"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"8869","DOI":"10.1007\/s00464-022-09322-7","article-title":"A machine learning analysis of difficulty scoring systems for laparoscopic liver surgery","volume":"36","author":"Ruzzenente","year":"2022","journal-title":"Surg. Endosc."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"205","DOI":"10.1097\/01.sla.0000133083.54934.ae","article-title":"Classification of surgical complications: A new proposal with evaluation in a cohort of 6336 patients and results of a survey","volume":"240","author":"Dindo","year":"2004","journal-title":"Ann. Surg."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"713","DOI":"10.1016\/j.surg.2010.10.001","article-title":"Posthepatectomy liver failure: A definition and grading by the International Study Group of Liver Surgery (ISGLS)","volume":"149","author":"Rahbari","year":"2011","journal-title":"Surgery"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"680","DOI":"10.1016\/j.surg.2010.12.002","article-title":"Bile leakage after hepatobiliary and pancreatic surgery: A definition and grading of severity by the International Study Group of Liver Surgery","volume":"149","author":"Koch","year":"2011","journal-title":"Surgery"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"821","DOI":"10.1097\/SLA.0000000000005668","article-title":"An International Expert Delphi Consensus on Defining Textbook Outcome in Liver Surgery (TOLS)","volume":"277","author":"Gorgec","year":"2023","journal-title":"Ann. Surg."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"110399","DOI":"10.1016\/j.ejso.2025.110399","article-title":"When is surgery futile? A systematic review of conflicting definitions and patterns in surgical care for advanced gastrointestinal cancer","volume":"51","author":"Lee","year":"2025","journal-title":"Eur. J. Surg. Oncol."},{"key":"ref_24","first-page":"20150202","article-title":"Principal component analysis: A review and recent developments","volume":"374","author":"Jolliffe","year":"2016","journal-title":"Philos. Trans. A Math. Phys. Eng. Sci."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"141","DOI":"10.1177\/001316446002000116","article-title":"The Application of Electronic Computers to Factor Analysis","volume":"20","author":"Kaiser","year":"1960","journal-title":"Educ. Psychol. Meas."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"803","DOI":"10.2307\/2532201","article-title":"Model-Based Gaussian and Non-Gaussian Clustering","volume":"49","author":"Banfield","year":"1993","journal-title":"Biometrics"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"15","DOI":"10.1016\/j.jare.2019.01.001","article-title":"Gaussian mixture model for texture characterization with application to brain DTI images","volume":"16","author":"Moraru","year":"2019","journal-title":"J. Adv. Res."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"31","DOI":"10.1007\/BF02291575","article-title":"An index of factorial simplicity","volume":"39","author":"Kaiser","year":"1974","journal-title":"Psychometrika"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"S2","DOI":"10.1016\/j.amjmed.2008.01.001","article-title":"Overconfidence as a cause of diagnostic error in medicine","volume":"121","author":"Berner","year":"2008","journal-title":"Am. J. Med."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"155","DOI":"10.4174\/jkss.2012.83.3.155","article-title":"Is close monitoring in the intensive care unit necessary after elective liver resection?","volume":"83","author":"Kim","year":"2012","journal-title":"J. Korean Surg. Soc."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"2491","DOI":"10.1007\/s11605-019-04408-5","article-title":"Routine Intensive Care Unit Admission Following Liver Resection: What Is the Value Proposition?","volume":"24","author":"Merath","year":"2020","journal-title":"J. Gastrointest. Surg."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"42","DOI":"10.1016\/j.bja.2018.07.029","article-title":"Critical care usage after major gastrointestinal and liver surgery: A prospective, multicentre observational study","volume":"122","author":"Collaborative","year":"2019","journal-title":"Br. J. Anaesth."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1097\/MS9.0000000000000114","article-title":"Futility considerations in surgical ethics","volume":"85","author":"Udwadia","year":"2023","journal-title":"Ann. Med. Surg."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"109594","DOI":"10.1016\/j.ejso.2025.109594","article-title":"Up-front resection for hepatocellular carcinoma: Assessing futility in the preoperative setting","volume":"51","author":"Altaf","year":"2025","journal-title":"Eur. J. Surg. Oncol."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"496","DOI":"10.1007\/s11605-017-3632-6","article-title":"Predictors of Futile Liver Resection for Patients with Barcelona Clinic Liver Cancer Stage B\/C Hepatocellular Carcinoma","volume":"22","author":"Li","year":"2018","journal-title":"J. Gastrointest. Surg."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1227","DOI":"10.1002\/jso.25281","article-title":"Pre-operative predictors of early recurrence\/mortality including the role of inflammatory indices in patients undergoing partial hepatectomy for spontaneously ruptured hepatocellular carcinoma","volume":"118","author":"Chua","year":"2018","journal-title":"J. Surg. Oncol."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1106","DOI":"10.1007\/s11605-023-05592-1","article-title":"Preoperative Predictors of Early Recurrence After Liver Resection for Multifocal Hepatocellular Carcinoma","volume":"27","author":"Guo","year":"2023","journal-title":"J. Gastrointest. Surg."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"42954","DOI":"10.1038\/srep42954","article-title":"Novel Preoperative Nomogram for Prediction of Futile Resection in Patients Undergoing Exploration for Potentially Resectable Intrahepatic Cholangiocarcinoma","volume":"7","author":"Nam","year":"2017","journal-title":"Sci. Rep."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"905","DOI":"10.1245\/s10434-021-10761-0","article-title":"Preventing Futile Liver Resection: A Risk-Based Approach to Surgical Selection in Major Hepatectomy for Colorectal Cancer","volume":"29","author":"Fromer","year":"2022","journal-title":"Ann. Surg. Oncol."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1277","DOI":"10.1007\/s11605-023-05673-1","article-title":"Textbook Outcomes in Liver Surgery: A Systematic Review","volume":"27","author":"Sweigert","year":"2023","journal-title":"J. Gastrointest. Surg."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"102005","DOI":"10.1016\/j.gassur.2025.102005","article-title":"Use of textbook outcome as a quality metric in hepatopancreaticobiliary surgery: A systematic review and meta-analysis","volume":"29","author":"Dawood","year":"2025","journal-title":"J. Gastrointest. Surg."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"3809","DOI":"10.1200\/JCO.2015.61.9239","article-title":"Outcomes of Prognostic Disclosure: Associations With Prognostic Understanding, Distress, and Relationship With Physician Among Patients With Advanced Cancer","volume":"33","author":"Enzinger","year":"2015","journal-title":"J. Clin. Oncol."},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Pagani, M., De Vincenti, R., Cecchi, C., Apollinari, A., Pesi, B., Leo, F., Giannessi, S., and Fedi, M. (2023). Hepatic Resection in Patients with Colo-Rectal Liver Metastases: Surgical Outcomes and Prognostic Factors of Single-Center Experience. J. Clin. Med., 12.","DOI":"10.3390\/jcm12062170"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"267","DOI":"10.1016\/j.gassur.2024.01.003","article-title":"The oncologic outcome and prognostic factors for solitary colorectal liver metastasis after liver resection","volume":"28","author":"Hsu","year":"2024","journal-title":"J. Gastrointest. Surg."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"209","DOI":"10.4254\/wjh.v14.i1.209","article-title":"Prognostic factors of survival and a new scoring system for liver resection of colorectal liver metastasis","volume":"14","author":"Cheng","year":"2022","journal-title":"World J. Hepatol."},{"key":"ref_46","doi-asserted-by":"crossref","unstructured":"Conticchio, M., Uldry, E., Hubner, M., Digklia, A., Fraga, M., Sempoux, C., Raisaro, J.L., and Fuks, D. (2025). Prognostic Factors in Colorectal Liver Metastases: An Exhaustive Review of the Literature and Future Prospectives. Cancers, 17.","DOI":"10.3390\/cancers17152539"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"293","DOI":"10.1159\/000354310","article-title":"Prognostic factors and survival after resection of colorectal liver metastasis in the era of preoperative chemotherapy: An 11-year single-centre study","volume":"30","author":"John","year":"2013","journal-title":"Dig. Surg."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"1620","DOI":"10.1016\/j.ejso.2020.05.019","article-title":"Does the difficulty grade of laparoscopic liver resection for colorectal liver metastases correlate with long-term outcomes?","volume":"46","author":"Holowko","year":"2020","journal-title":"Eur. J. Surg. Oncol."}],"container-title":["Cancers"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-6694\/18\/3\/407\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,27]],"date-time":"2026-01-27T15:53:22Z","timestamp":1769529202000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-6694\/18\/3\/407"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,1,27]]},"references-count":48,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2026,2]]}},"alternative-id":["cancers18030407"],"URL":"https:\/\/doi.org\/10.3390\/cancers18030407","relation":{},"ISSN":["2072-6694"],"issn-type":[{"value":"2072-6694","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,1,27]]}}}