低级阑尾癌（LGAC）在细胞减灭术和高温腹腔化疗（CRS/HIPEC）后，主要表现为腹腔内复发（IPR），而高级别肿瘤（HG）则同时进行腹腔内和腹腔外的进展（EPR）。然而，缺乏支持这一概念的证据；因此，我们评估了不同AC组织学的复发情况。采用单中心数据库（1998-2022）进行了一项回顾性队列研究。确定了LG、HG、高级别伴有信号鞘细胞（SRC）和杯状细胞癌（GCC）的复发模式（IPR、EPR、组合）。我们纳入了432例完全切除（CC-0/1）CRS/HIPEC：200例LG、114例HG、72例SRC和46例GCC。中位随访时间为78个月（95％置信区间[CI]为70-86个月）。总体而言，有34％（n = 148）的患者复发。IPR是最常见的复发模式（LG 16％，HG 27％，SRC 36％，GCC 26％），复发的中位时间（MTR）为21个月（IQR：12-40个月）。EPR（肝脏、肺、胸膜、淋巴结或骨骼）发生在LG 3％，HG 9％，SRC 22％和GCC 7％。MTR为11个月（IQR：4-16个月）。组合模式发生在LG 0％，HG 8％，SRC 7％和GCC 0％。MTR为13个月（IQR：7-18个月）。53％的IPR进行了迭代手术，18％的EPR进行了迭代手术，51％的组合进行了迭代手术。与EPR和组合复发相比，IPR后复发生存时间更长：36个月（95％CI为25-47个月）对比13个月（95％CI为7-19个月）和18个月（95％CI为6-30个月）（p <0.01）。完全CRS/HIPEC后，IPR是所有AC组织学中的主要模式，并且发生较晚。IPR后复发生存时间更长。了解AC的复发模式有助于理解其生物学，并制定后续随访和复发后管理计划。© 2023.外科肿瘤学会。

It is thought that low-grade (LG) appendiceal cancer (AC) demonstrates predominantly intraperitoneal recurrence (IPR) after cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC), whereas high-grade (HG) tumors progress both intra- and extraperitoneally (EPR). However, evidence supporting this conception is lacking; therefore, we assessed recurrence in various AC histologies.A retrospective, cohort study was conducted by using a single-center database (1998-2022). Recurrence patterns (IPR, EPR, combined) were identified for LG, HG, high-grade with signet ring cells (SRC), and goblet cell carcinoma (GCC).We included 432 complete (CC-0/1) CRS/HIPECs: 200 LG, 114 HG, 72 SRC, and 46 GCC. Median follow-up was 78 (95% confidence interval [CI] 70-86) months. Overall, 34% (n = 148) of patients recurred. IPR was the most common (LG 16%, HG 27%, SRC 36%, GCC 26%) with median time to recurrence (MTR) of 21 (IQR: 12-40) months. EPR (liver, lung, pleura, lymph nodes, or bones) occurred in LG 3%, HG 9%, SRC 22%, and GCC 7%. MTR was 11 (IQR: 4-16) months. Combined pattern occurred in LG 0%, HG 8%, SRC 7%, and GCC 0%. MTR was 13 (IQR: 7-18) months. Iterative surgery was performed in 53% IPR, 18% EPR, and 51% combined. Median post-recurrence survival was longer after IPR compared with EPR and combined recurrence: 36 (95% CI 25-47) versus 13 (95% CI 7-19) and 18 (95% CI 6-30) months (p < 0.01).After complete CRS/HIPEC, IPR was the predominant pattern in all AC histologies and occurred later. Post-recurrence survival after IPR was longer. Knowing AC recurrence patterns can help to understand its biology and plan follow-up and post-relapse management.© 2023. Society of Surgical Oncology.