S2 Fig -

Background
Lymph node status and lymph node count (LNC) are predictors of colorectal cancer outcome. Under-sampling of lymph nodes may lead to clinically relevant stage migration.
Methods
Colorectal cancer (CRC) cases with a synoptic report, accessioned 2012–2020 at a regional laboratory, were extracted and retrospectively studied. LNC, positive lymph node count (PLNC), tumour deposits present (TDpos), and ‘y’ (staging) prefix (YS) were retrieved and tabulated by pathologist using custom software. Statistical analyses were done with R.
Data and results
The cohort had 2,543 CRC resections. Seventeen pathologists interpreted >50 cases (range: 56–356) each and collectively saw 2,074. After cases with unavailable data were purged, 2,028 cases remained with 43,996 lymph nodes, of which 2,637/43,996 were positive. 368 cases had a ‘y’ prefix, and 379 had TDpos. The 17 pathologists’ median LNC/case was 19.0 (range: 14.0–24.0), and the mean PLNC per case was 1.4 (range: 1.0–2.0). Kruskal-Wallis rank sum tests showed there were differences in LNC (p<0.001) among pathologists; however, PLNC did not show this association (p = 0.2917). T-tests showed that mean LNC (p<0.001) and PLNC (p<0.035) differed between YS. 138 of 2,028 cases had less than the 12 LNC target. Logistic regression revealed a strong association between meeting the LNC target and pathologist (p<0.001) but TDpos was non-predictive (p = 0.4736).
Conclusions
Positive lymph node call rate has a good consistency in the laboratory; however, lymph node count varies significantly between pathologists. Standardized counting criteria are needed to improve uniformity and could be aided by synoptic reporting data.

研究背景
淋巴结状态与淋巴结计数（Lymph Node Count, LNC）是结直肠癌预后的预测因子。淋巴结采样不足可能导致具有临床意义的分期迁移。

研究方法
提取2012年至2020年于某区域实验室归档入库的、带有病理概要报告的结直肠癌（Colorectal Cancer, CRC）病例并开展回顾性研究。由病理医师借助定制化软件提取淋巴结计数（Lymph Node Count, LNC）、阳性淋巴结计数（Positive Lymph Node Count, PLNC）、存在肿瘤沉积（Tumour Deposits Present, TDpos）以及“y”（分期）前缀（Staging Prefix, YS）并制表汇总。统计学分析采用R语言完成。

数据与结果
本队列共纳入2543例结直肠癌切除术病例。17名病理医师每人阅片量超50例（区间：56~356例），累计阅片2074例。剔除数据缺失的病例后，剩余2028例，共计43996枚淋巴结，其中2637枚为阳性淋巴结。368例带有“y”分期前缀，379例存在肿瘤沉积。17名病理医师的单病例淋巴结计数中位数为19.0（区间：14.0~24.0），单病例阳性淋巴结计数均值为1.4（区间：1.0~2.0）。克鲁斯卡尔-沃利斯秩和检验显示，不同病理医师间的淋巴结计数存在显著差异（p<0.001），但阳性淋巴结计数无此关联（p=0.2917）。t检验显示，带有“y”分期前缀的病例与未带前缀的病例之间，淋巴结计数均值（p<0.001）与阳性淋巴结计数均值（p<0.035）均存在显著差异。2028例中有138例的淋巴结计数未达到12枚的目标阈值。Logistic回归分析显示，是否达到淋巴结计数目标阈值与病理医师存在强关联（p<0.001），但肿瘤沉积状态无预测价值（p=0.4736）。

研究结论
本实验室中阳性淋巴结检出率一致性良好，但不同病理医师间的淋巴结计数差异显著。需建立标准化的计数标准以提升诊断一致性，病理概要报告数据可为此提供辅助支撑。