[Association between gross tumor regression patterns, distal resection margin distance, and local recurrence in rectal cancer after neoadjuvant therapy].

内容摘要

Objective: To investigate the associations of macroscopic tumor regression patterns and distal resection margin (DRM) distance with local recurrence in patients with rectal cancer after neoadjuvant chemoradiotherapy (nCRT), and to provide evidence for surgical decision-making and intraoperative assessment of the distal resection extent. Methods: This single-center retrospective cohort study used data from the prospective MONT-R registry. A total of 410 patients with mid-to-low locally advanced rectal cancer who underwent nCRT followed by radical surgery at Peking Union Medical College Hospital between December 2017 and September 2022 were included. Of these, 276 patients were male (67.3%), and the median age was 60 years (interquartile range [IQR], 51-67 years). According to the gross appearance of postoperative specimens, tumors were classified as scar-like, ulcerative, or protruding mass-type patterns. Clinicopathological characteristics, DRM distance, and the incidence of inadequate DRM, defined as DRM ≤0.5 cm, were compared among groups. Disease-free survival (DFS) and local recurrence-free survival (LRFS) were analyzed using the Kaplan-Meier method. Results: Of the 410 patients, 42 (10.2%) had scar-like tumors, 360 (87.8%) had ulcerative tumors, and 8 (2.0%) had protruding mass-type tumors. The lymph node metastasis rate differed significantly among groups (χ²=8.63, P=0.013), with no lymph node metastasis observed in the scar-like group, compared with 17.2% (62/360) in the ulcerative group and 1/8 in the protruding mass-type group. Pathological tumor diameter also differed significantly among groups (H=11.82, P=0.003) , with the mass-type showing the largest diameter [median (Q1, Q3): 2.9 (2.3, 4.0) cm], whereas no obvious difference was observed between the ulcerative type [2.0 (1.3, 2.5) cm] and the scar-like type [1.5 (1.2, 2.0) cm]. The distributions of ypT stage, perineural invasion, and lymphovascular invasion did not differ significantly among groups (all P>0.05). Only 4 patients had a positive circumferential resection margin; all of whom were in the ulcerative group. The proportions of CAP 0-1 tumor regression and pathological complete response were higher in the scar-type group than in the other groups, but the differences were not statistically significant (P=0.098 and P=0.081, respectively). The median DRM distances in the scar-type, ulcerative-type, and protruding mass-type groups were 1.15 (0.20, 2.00) cm, 1.70 (1.00, 2.75) cm, and 2.55 (1.38, 3.62) cm, respectively, with a significant difference among groups (H=9.67, P=0.008). The incidence of inadequate DRM was significantly higher in the scar-type group than in the ulcerative-type and protruding mass-type groups [38.1% (16/42) vs. 15.3% (55/360) vs. 1/8; χ²=13.67, P=0.001]. During a median follow-up of 51 months (IQR, 36-64 months), no significant differences were observed in DFS (P=0.947) or LRFS (P=0.175) among the three groups. Similarly, DFS (P=0.731) and LRFS (P=0.131) did not differ significantly between patients with inadequate and adequate distal resection margins. Conclusions: After nCRT for rectal cancer, patients with a scar-like macroscopic tumor regression pattern had a lower risk of lymph node metastasis and a shorter DRM. However, in the setting of standardized total mesorectal excision, a shorter DRM was not associated with adverse survival outcomes. 目的： 探讨新辅助放化疗后直肠癌不同肉眼退缩形态及远切缘距离（DRM）与局部复发之间的关系，为手术方式及术中远端切除范围评估提供参考。 方法： 采用单中心回顾性队列研究的方法，患者来源于MONT-R前瞻性注册研究队列。回顾性收集2017年12月至2022年9月在北京协和医院接受新辅助治疗并行根治性手术的410例中低位局部进展期直肠癌患者资料，男性276例（67.3%），中位年龄为60（51，67）岁。根据术后标本肉眼退缩形态分为瘢痕型、溃疡型和肿物隆起型。比较不同退缩形态患者的临床病理特征、DRM及DRM不足（DRM≤0.5 cm）发生率。采用Kaplan-Meier法分析不同组间无病生存（DFS）及局部无复发生存（LRFS）的差异。 结果： 410例患者中，瘢痕型42例（10.2%），溃疡型360例（87.8%），肿物隆起型8例（2.0%）。不同肉眼退缩形态患者的临床病理特征的比较显示，瘢痕型患者未见淋巴结转移，而溃疡型及肿物隆起型患者的淋巴结转移率分别为17.2%（62/360）和1/8，组间差异具有统计学意义（χ²=8.63，P=0.013）；病理肿瘤长径组间差异具有统计学意义（H=11.82，P=0.003），其中，肿物隆起型最长［M（Q1，Q3）：2.9（2.3，4.0）cm］，溃疡型［2.0（1.3，2.5）cm］与瘢痕型［1.5（1.2，2.0）cm］之间差异不明显；不同退缩形态患者在ypT分期分布、神经侵犯及脉管癌栓发生率方面差异均无统计学意义（均P>0.05）；在术后病理评估中，仅有4例患者（均为溃疡型）出现环周切缘阳性，其余患者均为阴性；在病理治疗反应方面，瘢痕型患者CAP 0~1的比例以及病理完全缓解的发生率均高于溃疡型及肿物隆起型患者，但差异未达到统计学意义（P=0.098和P=0.081）。瘢痕型、溃疡型及肿物隆起型患者的中位DRM分别为1.15（0.20，2.00）cm、1.70（1.00，2.75）cm和2.55（1.38，3.62）cm，组间比较差异具有统计学意义（H=9.67，P=0.008）。瘢痕型患者DRM不足的发生率为38.1%（16/42），明显高于溃疡型（15.3%，55/360）和肿物隆起型患者（1/8），组间差异具有统计学意义（χ²=13.67，P=0.001）。中位随访时间为51（36，64）个月，不同肉眼肿瘤退缩形态患者DFS（P=0.947）及LRFS（P=0.175）差异均无统计学意义。DRM不足和DRM充足患者的DFS（P=0.731）和LRFS（P=0.131）差异亦无统计学意义。 结论： 直肠癌新辅助治疗后，不同肉眼肿瘤退缩形态中瘢痕型患者淋巴结转移风险较低，其远切缘较短，但在规范TME基础上，较短DRM未观察到对生存结局的影响。.