Kato, YutaroSugioka, AtsushiKojima, MasayukiSyn, Nicholas LZhongkai, WangLiu, RongCipriani, FedericaArmstrong, ThomasAghayan, Davit LSiow, Tiing-FoongLim, ChetanaScatton, OlivierHerman, PauloCoelho, Fabricio FerreiraMarino, Marco VMazzaferro, VincenzoChiow, Adrian K HSucandy, IswantoIvanecz, ArpadChoi, Sung HoonLee, Jae HoonGastaca, MikelVivarelli, MarcoGiuliante, FeliceDalla Valle, BernardoRuzzenente, AndreaYong, Chee-ChienFondevila, ConstantinoEfanov, MikhailDi Benedetto, FabrizioBelli, AndreaPark, James ORotellar, FernandoChoi, Gi-HongRobles-Campos, RicardoWang, XiaoyingSutcliffe, Robert PSchmelzle, MoritzPratschke, JohannLai, Eric C HChong, Charing C ND'Hondt, MathieuMonden, KazuteruLopez-Ben, SantiagoKingham, T PeterForchino, FabioFerrero, AlessandroEttorre, Giuseppe MariaLevi Sandri, Giovanni BattistaPascual, FrancoCherqui, DanielSoubrane, OlivierWakabayashi, GoTroisi, Roberto ICheung, Tan-ToChen, ZeweiYin, MengqiuD'Silva, MizelleHan, Ho-SeongNghia, Phan PhuocLong, Tran Cong DuyEdwin, BjørnFuks, DavidChen, Kuo-HsinAbu Hilal, MohammadAldrighetti, LucaGoh, Brian K P2023-11-172023-11-172023-10-30Kato, Y., Sugioka, A., Kojima, M., Syn, N. L., Zhongkai, W., Liu, R., Cipriani, F., Armstrong, T., Aghayan, D. L., Siow, T. F., Lim, C., Scatton, O., Herman, P., Coelho, F. F., Marino, M. V., Mazzaferro, V., Chiow, A. K. H., Sucandy, I., Ivanecz, A., Choi, S. H., … International Robotic and Laparoscopic Liver Resection Study Group Investigators (2023). Impact of Tumor Size on the Difficulty of Laparoscopic Major Hepatectomies: An International Multicenter Study. Annals of surgical oncology, 30(11), 6628–6636. https://doi.org/10.1245/s10434-023-13863-z1534-468110.1245/s10434-023-13863-z37505351http://hdl.handle.net/20.500.14200/2915Abstract Introduction: Although tumor size (TS) is known to affect surgical outcomes in laparoscopic liver resection (LLR), its impact on laparoscopic major hepatectomy (L-MH) is not well studied. The objectives of this study were to investigate the impact of TS on the perioperative outcomes of L-MH and to elucidate the optimal TS cutoff for stratifying the difficulty of L-MH. Methods: This was a post-hoc analysis of 3008 patients who underwent L-MH at 48 international centers. A total 1396 patients met study criteria and were included. The impact of TS cutoffs was investigated by stratifying TS at each 10-mm interval. The optimal cutoffs were determined taking into consideration the number of endpoints which showed a statistically significant split around the cut-points of interest and the magnitude of relative risk after correction for multiple risk factors. Results: We identified 2 optimal TS cutoffs, 50 mm and 100 mm, which segregated L-MH into 3 groups. An increasing TS across these 3 groups (≤ 50 mm, 51-100 mm, > 100 mm), was significantly associated with a higher open conversion rate (11.2%, 14.7%, 23.0%, P < 0.001), longer operating time (median, 340 min, 346 min, 365 min, P = 0.025), increased blood loss (median, 300 ml, ml, 400 ml, P = 0.002) and higher rate of intraoperative blood transfusion (13.1%, 15.9%, 27.6%, P < 0.001). Postoperative outcomes such as overall morbidity, major morbidity, and length of stay were comparable across the three groups. Conclusion: Increasing TS was associated with poorer intraoperative but not postoperative outcomes after L-MH. We determined 2 TS cutoffs (50 mm and 10 mm) which could optimally stratify the surgical difficulty of L-MH. Keywords: Difficulty; Laparoscopic liver resection; Major hepatectomy; Minimally invasive liver; Size.en© 2023. Society of Surgical Oncology.SurgeryOncology. Pathology.GastroenterologyArticle