VEGFR3与结肠癌淋巴结转移的临床研究

探讨血管内皮生长因子受体(VEGFR3)在结肠癌淋巴结转移中的意义.对99例术后结肠癌及其癌旁组织石蜡包埋标本构建组织芯片并进行免疫组织化学染色,探测其表达强度并结合临床资料进行分析.结果表明结肠癌细胞表达VEGFR3与Duke's分期有关,Duke's C,D期结肠癌细胞表达VEGFR3较Duke's A,B期显著升高(P＜0.01),与局部淋巴结转移相关(P＜0.05).癌与癌旁组织表达差异显著(P＜0.01).分化良好者与分化不良者表达差异显著(P＜0.01).结论:结肠癌随病情加重,肿瘤细胞表达VEGFR3与诱发局部淋巴结转移相关.     

VEGF-D的表达与结肠癌淋巴管生成及淋巴结转移的相关性

目的探讨血管内皮生长因子-D(Vascular endothelial growth factorD,VEGF-D)在结肠癌组织中的表达规律,及其与结肠癌淋巴管密度(LVD)、淋巴结转移之间的关系。方法采用免疫组化法对43例人结肠癌组织和14例结肠良性病变组织的VEGF-D表达进行分析,以LYVE-1标记淋巴管,测算淋巴管密度,统计分析结肠癌中的VEGF-D表达与结肠癌临床病理特征的关系。采用Western-blot法检测16例人结肠癌组织中淋巴结转移组和无淋巴结转移组的VEGF-D蛋白表达。结果免疫组化结果显示结肠癌组织中VEGF-D的阳性率明显高于结肠良性病变组织,并且与结肠癌组织的LVD成正相关。Western-blot结果显示结肠癌中淋巴结转移组的VEGF-D的表达量较无淋巴结转移组明显增加,VEGF-D表达与患者的肿瘤浸润深度、淋巴结转移和Dukes分期显著相关,而与年龄和肿瘤大小无关。结论结肠癌组织中VEGF-D的高表达可能与结肠癌的淋巴管的新生及淋巴结转移有关。     

miR-23a与转移抑制因子1在结肠癌中的表达及其临床意义

目的 探讨miR-23a( Homo sapiens miR-23a)与转移抑制因子1(metastasis suppressor 1,MTSS1)在结肠癌中的表达情况及其临床意义.方法 运用荧光素报告载体系统检测miR-23a直接调控的靶基因并采用Transwell侵袭实验检测miR-23a对人结肠癌SW620细胞的侵袭能力.收集结肠癌患者手术标本92例,癌旁组织作为正常对照,分别运用原位杂交、免疫组织化学EliVision法检测结肠癌组织及癌旁组织中miR-23a、MTSS1的表达水平,并对二者进行相关性分析.结果 MTSS1是miR-23a直接调控的靶基因,miR-23a下调MTSS1蛋白的表达,增强结肠癌细胞侵袭能力.在92例结肠癌组织中miR-23a阳性表达率为87.0％( 80/92),MTSS1蛋白阳性表达率为17.4％(16/92),分别与癌旁对照组比,差异有统计学意义(P ＜0.01);miR-23a的表达随着结肠癌临床分期演进(P =0.029)和浸润深度增加而增加(P=0.000),且有淋巴结转移的miR-23a的表达显著高于无淋巴结转移组(P=0.041);MTSS1的表达随着结肠癌临床分期演进(P=0.027)和浸润深度增加而下调(P=0.017),且有淋巴结转移的MTSS1的表达显著低于无淋巴结转移组(P=0.009);相关性分析表明,miR-23a表达与MTSS1的表达呈显著负相关(r=-0.594,P=0.013).结论 miR-23a通过靶向抑制MTSS1促进结肠癌SW620细胞生长、侵袭转移;miR-23a的高表达和MTSS1蛋白低表达可能是肠黏膜恶性转变以及结肠癌发生浸润转移的重要生物学标志,检测二者对预测结肠癌浸润转移有重要意义.     

可诱导 T 细胞共刺激分子在结肠癌组织中的表达情况及其与 远期生存的相关性研究

目的 探讨分析可诱导 T 细胞共刺激分子 (inducible T-cell co-stimulator, ICOS) 在结肠癌组织中 的表达情况及其与远期生存的相关性。 方法 选取 2018 年 5 月至 2019 年 5 月期间在大连大学附属新华医 院进行手术切除结肠组织的 206 例结肠癌患者作为研究对象, 取其结肠癌组织及癌旁组织标本, 使用荧光 定量 PCR 检测结肠癌组织及癌旁组织中可诱导 T 细胞共刺激分子表达水平, 分析其表达与临床病理特征的 关系及远期生存的相关性。 结果 结肠癌组织中 ICOS 表达水平 (8. 73 ± 2. 25) 显著低于癌旁组织的 (18. 54 ± 3. 26), 差异有统计学意义 (P< 0. 05); 结肠癌组织中 ICOS 表达水平与肿瘤直径、 远处转移、 临 床分期、 淋巴结转移有关 ( P < 0. 05), 与年龄、 性别、 肿瘤部位、 分化程度差异无统计学意义 ( P > 0. 05); ICOS 表达在 206 例结肠癌组织的中低表达 117 例, 高表达 89 例; ICOS 高表达和低表达与临床病理 因素进行 Logistic 二次回归分析结果显示, ICOS 表达与肿瘤大小、 临床分期、 淋巴结转移、 远处转移有关 (P< 0. 05), 与年龄、 性别、 肿瘤位置、 分化程度无关 (P > 0. 05); 随访截止至 2021 年 9 月 30 日, 206 例 结肠癌患者存活率 83. 01 % (171 / 206), 死亡率 16. 99 % (35 / 206), 中位生存时间为 (23. 5 ± 3. 3) 个 月。 ICOS 高表达的 89 例结肠癌患者的中位生存期为 (27. 4 ± 3. 2) 个月, 95 % CI 为 2. 234 ~ 6. 147; ICOS 低表达的 117 例结肠癌患者的中位生存期为 (16. 3 ± 4. 3) 个月, 95 % CI 为 1. 458 ~ 5. 237, ICOS 高表达结 肠癌患者中位生存期显著高于 ICOS 低表达者 (P< 0. 05)。 结论 ICOS 在结肠癌组织中呈较低表达, 其表 达水平与患者远期生存呈正相关关系, 其水平可作为结肠癌患者预后生存的重要评估指标。     

Trop-2在结直肠癌组织中的表达及其意义

目的 探讨人滋养层细胞表面抗原-2(Trop-2)在结直肠癌中的表达及其意义.方法 用免疫组化法检测84例结直肠癌组织标本及其相对应的癌旁正常组织中的Trop-2表达情况,分析其表达与临床病理特点的关系,进一步采用Westem blot检测34例手术标本的Trop-2表达情况.结果 Trop-2在结直肠癌组织中的表达高于癌旁正常组织(P ＜0.05);Trop-2表达量:直肠癌(RC)组＞左半结肠癌(LSCC)组＞右半结肠癌(RSCC)组(P＜0.05),Dukes'C+D组＞A+B组(P＜0.05),淋巴结转移组＞无淋巴结转移组(P＜0.05),远处转移组＞无远处转移组(P＜0.05);与性别、年龄、分化程度无关.结论 Trop-2在结直肠癌组织中高表达,与Dukes分期、淋巴结转移、远处转移和肿瘤所在部位有关.     

SDF-1和VEGF-C在结肠癌中的表达及与淋巴结转移的关系

目的探讨结肠癌组织中基质细胞衍生因子SDF-1、血管内皮生长因子-C（VEGF-C）表达的相互关系及其在淋巴结转移过程中的作用和可能机制。方法应用免疫组化法检测70例结肠癌组织和12例癌旁组织中SDF-1及VEGF-C的表达水平。结果结肠癌组织中SDF-1、VEGF-C阳性表达率分别为71．4％、64．3％，显著高于癌旁非癌组织的16．7％和8．3％（P〈0．01）。SDF-1、VEGF-C的表达与结肠癌的浸润深度、淋巴结转移及TNM分期有关（P〈0、01或P〈0．05），与结肠癌的分化程度、远处转移无关（P〉0．05）。SDF-1、VEGF-C之间表达呈正相关（r=0．608，P〈0．05）。结论结肠癌组织中SDF-1、VEGF-C表达均显著增高，两者在结肠癌淋巴结转移中可能具有协同效应，共同促进结肠癌的淋巴结转移。     

HAb18G/CD147在多种恶性肿瘤中的表达及其临床意义

目的 探讨HAb18G/CD147表达与食管癌、结肠癌、宫颈癌、肺癌、卵巢癌和肝细胞癌的临床相关性.方法 应用免疫组织化学SP染色法分析上述6种恶性肿瘤及其癌旁组织和淋巴结转移灶标本中CD147基因表达和定位,并对CD147表达与肿瘤分化程度、浸润深度、淋巴结转移情况进行分析.结果 相对于癌旁组织,CD147在6种肿瘤中的表达均明显生升高.CD147表达与肿瘤的分化程度、浸润深度和淋巴结转移均显著正相关.结肠癌、宫颈癌以及食管癌中,CD147在浸润深的组织中的表达显著升高(P＜0.05);宫颈癌、食管癌、肺癌以及卵巢癌中,CD147在淋巴结转移灶中的表达显著升高(P＜0.05),但在结肠癌中差别不显著;结肠癌、宫颈癌、食管癌以及肺癌中,CD147在分化差的组织中的表达显著升高(P＜0.05).结论 CD147表达在分化差、浸润深以及淋巴结转移的组织中明显升高,提示CD147可能是恶性肿瘤的预后指标.     

miR-625-3p在结肠癌组织和细胞中的表达

目的:探讨微小RNA(mi R)-625-3p在结肠癌组织和细胞中的表达,了解其作用机制。方法:利用q RT-PCR分析结肠癌细胞株、癌组织和癌旁组织中mi R-625-3p的表达水平,探讨mi R-625-3p表达水平与结肠癌临床病理参数之间的关系;利用碘化丙啶染色和流式细胞术检测细胞凋亡和细胞周期变化;Western blot法检测mi R-625-3p对结肠癌细胞株凋亡相关蛋白的影响,初步了解其发挥影响的可能机制。结果:结肠癌组织mi R-625-3p的表达量比癌旁组织高(P0.05),mi R-625-3p的表达量与结肠癌浸润深度、TNM分期及有无远处转移关系密切(P0.05)。mi R-625-3p在结肠癌SW620细胞中的表达水平高于在SW480细胞中的表达。抑制mi R-625-3p的表达能显著抑制结肠癌细胞的周期(P0.05)和促进凋亡;转染mi R-625-3p后,Bcl-2的表达量增加(P0.05),Bax表达量没有显著变化。结论:mi R-625-3p能促进结肠癌细胞增殖,抑制结肠癌细胞凋亡,可能是结肠癌新的抗癌靶点。     

VEGF-C和Smad4在结肠癌淋巴管生成和淋巴道转移中的作用

目的研究血管内皮生长因子C(VEGF-C)和Smad4对结肠癌淋巴管生成、淋巴结转移的影响。方法应用免疫组化方法检测79例人结肠癌组织中VEGF-C、VEGFR-3、TGF-β1、TβR-Ⅱ和Smad4的表达和淋巴管密度(LVD)。结果 LVD与VEGF-C表达水平呈正相关、与Smad4表达呈负相关;有淋巴结转移的人结肠癌组织VEGF-C表达水平高于无淋巴结转移者(<0.001)、Smad4表达低于无淋巴结转移者(=0.001);VEGF-C表达与Smad4表达呈负相关(<0.001,R=-0.507)。结论在结肠癌组织中VEGF-C和Smad4与淋巴管生成、淋巴道转移相关。     

血管内皮生长因子D和血管内皮生长因子受体3在人结肠癌中的表达及淋巴道转移中的作用

目的 观察血管内皮生长因子D(VEGF-D)和血管内皮生长因子受体3(VEGFR-3)在人结肠癌组织中的表达,检测结肠癌组织中的微淋巴管密度(LMVD),探讨VEGF-D和VEGFR-3在淋巴管生成以及结肠癌淋巴道转移中的作用.方法 选择55例不同时期,不同分化程度的人结肠癌组织样本,应用免疫组织化学染色的方法,观察VEGF-D和VEGFR-3在人结肠癌组织中的表达,应用Podoplanin标记淋巴管,检测结肠癌组织中的淋巴管密度.结果 在55例结肠癌组织中,VEGF-D的阳性表达率为54.5%,明显高于在癌周正常组织内的表达(P＜0.05);结肠癌组织中VEGFR-3表达的阳性率为69.1%,明显高于在癌周正常组织内的表达(P＜0.01);并且VEGFR-3的表达与VEGF-D的表达具有显著相关性(P＜0.01).在结肠癌组织中,淋巴结转移阳性组,浸润深度超过肌层组,DukeC、D期的VEGF-D的表达水平和LMVD明显高于淋巴结转移阴性组,浸润深度未超过肌层组,Duke A、B期(P＜0.01),经计数淋巴管数量,癌组织中的LMVD明显高于癌周正常组织(P＜0.01),并且LMVD与VEGF-D的表达显著相关(P＜0.01).结论 结肠癌组织中VEGF-D的表达水平随着癌的浸润和转移程度的增强而增高,并且通过上调其受体VEGFR-3的表达而促进癌组织中淋巴管的生成,从而促进癌的浸润和转移.     

A resected case of neuroendocrine carcinoma of the stomach with unusual lymph node metastasis

Gastric endocrine cell carcinoma is a relatively rare tumor. We experienced a case of early gastric cancer in which an endocrine cell carcinoma was identified within a differentiated adenocarcinoma, and a component of this endocrine cell carcinoma had metastasized to lymph nodes of the stomach. In its 2010 revision regarding digestive system tumors, WHO classified cancer cells with characteristics of both glandular system cells and neuroendocrine cells as mixed adeno neuroendocrine carcinoma (MANEC) under the neuroendocrine carcinoma (NEC) category. In this case, we observed an endocrine cell carcinoma continuous with an intramucosal differentiated adenocarcinoma, and cancer cells with an irregular gland duct structure were observed in the proliferative portion of the submucosal tissue. In addition, there was a 35 mm size lymph node metastasis in the lesser curvature of the stomach consisting entirely of poorly differentiated cancer cells with polymorphic, highly atypical nuclei and scant cytoplasm. Immunohistological analysis showed that the endocrine carcinoma in the gastric mucosa was chromogranin A positive and the infiltrated area of the submucosal tissue was also chromogranin A positive. The lymph node metastasis was positive not only for chromogranin A, but also for Synaptophysin and CD56. Furthermore, the Ki67 labeling index was high at approximately 80 % for the gastric endocrine cell carcinoma and approximately 90 % for the lymph node metastases. Until now, there are no reports related to the patients with early gastric cancer accompanied with lymph node metastasis of MANEC. This case is very interested in considering the mechanism of lymph node metastasis of MANEC. The patient has shown no sign of recurrence for 1 year and 4 months after postoperative chemotherapy.     

Dynamics of the cellular immune reactions in precancer and cancer of the large intestine

Ninety cases of colon precancer and cancer were examined histologically, histochemically and morphometrically from the viewpoint of cell immune reactions of local connective tissue and regional lymph nodes. It is found that the intensity of mutual cell responses of local connective tissue, colon lymph follicles and regional lymph nodes increases in parallel with the malignization of adenomatous polyps and villous adenomata, reaches a peak in the incipient carcinoma and rapidly decreases when the invasive growth starts. The correlation between the plasma cells and lymphoid cells changes, the relative density of the latter is the greatest in the incipient carcinoma. The data obtained may be used for the incipient carcinoma diagnosis and for prognosis.     

癌干细胞标记物CD44与ESA在舌癌淋巴道转移模型中的表达及其意义

目的:探讨癌干细胞标记物CD44与ESA蛋白在舌癌淋巴道转移模型中表达情况及其表达意义。方法:采用癌细胞足垫注射法建立淋巴道转移模型,4周后,取转移淋巴结进行原代细胞培养,从中分离、纯化舌癌细胞进行连续传代培养,建立舌癌永生化细胞系,命名为Tca8113-Ml。以舌癌永生化细胞系Tca8113-Ml为研究对象,采用足垫注射细胞的方法建立淋巴道转移模型。4周后,收集淋巴结,免疫组织化学染色检测癌干细胞标记物CD44与ESA蛋白的表达情况。结果:采用Tca8113-Ml建立了舌癌淋巴道转移模型,4周后收集淋巴结,检测癌干细胞标记物CD44与ESA蛋白在舌癌转移淋巴结组织中均呈阳性表达。结论:癌干细胞标记物在淋巴结转移性癌组织中呈阳性表达,表明淋巴结转移灶中有癌干细胞存在,提示癌转移的"种子"细胞极有可能是癌干细胞。     

磁性碳纳米管载附5-氟尿嘧啶对结肠癌淋巴结转移的靶向抑制作用☆

背景：将碳纳米管制备成磁靶向药物载体后,在磁场作用下能更好地把药物运送至体内靶器官或靶组织。 目的：观察磁性碳纳米管新化疗载体对结肠癌淋巴结转移的抑制效果。 方法：MTT法检测5-氟尿嘧啶、磁性多壁碳纳米管-5-氟尿嘧啶、磁性多壁碳纳米管(每种药物分别含0.000 3,0.003,0.03,0.3,3 g/L 5-氟尿嘧啶)对结肠癌SW480细胞的抑制作用。将含相同浓度5-氟尿嘧啶的5-氟尿嘧啶、磁性多壁碳纳米管-5-氟尿嘧啶、磁性多壁碳纳米管分散液分别注入SD大鼠足垫皮下及结肠癌淋巴结转移裸鼠体内。 结果与结论：体外各质量浓度的5-氟尿嘧啶和磁性多壁碳纳米管-5-氟尿嘧啶对癌细胞的毒性存在剂量依赖性,相同5-氟尿嘧啶质量浓度时两者对体外SW480细胞的抑制作用无明显差异,说明磁性多壁碳纳米管-5-氟尿嘧啶的主要药效成分为5-氟尿嘧啶。体内研究高效液相检测显示磁性多壁碳纳米管-5-氟尿嘧啶能有效聚集在淋巴结,长时间持久释放,淋巴结浓集效果明显优于5-氟尿嘧啶(P < 0.05),且不良反应小,肉眼容易辨识,细胞穿透性好;TUNNEL检测见磁性多壁碳纳米管-5-氟尿嘧啶化疗后结肠癌淋巴结转移灶细胞有明显凋亡现象,在磁场作用下效果更显著。说明磁性多壁碳纳米管-5-氟尿嘧啶对结肠癌SW480细胞淋巴结转移有明显抑制作用。关键词：磁性碳纳米管;5-氟尿嘧啶;淋巴化疗;结肠癌;淋巴结转移;生物材料与纳米技术 缩略语注释：5-FU：5-fluorouracil,5-氟尿嘧啶;mMWNTs：multi walled carbon nanotubes,磁性多壁碳纳米管 doi:10.3969/j.issn.1673-8225.2012.16.008      

乳腺癌前哨淋巴结活检术中不同染色淋巴结与肿瘤转移的关系

目的探讨乳腺癌前哨淋巴结活检术(SLNB)中不同染色情况的淋巴结与肿瘤转移的关系。方法选择我院2014年1月至2018年1月行前哨淋巴结活检的乳腺癌患者92例,以亚甲蓝为示踪剂,根据92例乳腺癌患者SLNB中淋巴结染色情况的不同分为无染色组、完全染色组和染色不均组,病理检测3组患者淋巴结的肿瘤转移情况并作比较。结果92例乳腺癌SLNB共取得淋巴结256枚,平均每例患者2.8枚,无染色组(80枚)肿瘤转移率为13.8%,完全染色组(112枚)肿瘤转移率为43.8%,染色不均组(64枚)肿瘤转移率为62.5%,3组间肿瘤转移率差异有统计学意义(P<0.05)。结论乳腺癌SLNB中染色不均的淋巴结最易出现肿瘤转移,其次为完全染色的淋巴结,染色淋巴结附近看到的未染色淋巴结也有肿瘤转移的可能,宜一并切除送检,有利于降低假阴性率。     

Lymphknotenpräparation bei kolorektalen Karzinomen

The UICC requires investigation of a minimum of 12 lymph nodes for adequate lymph node staging in colorectal cancer. Despite that, many authors recommend investigation of a larger number, and different techniques, such as fat clearance, have therefore been developed. In this study we introduce a novel technique involving ex vivo lymph node staining with intraarterial methylene blue injection in colon cancer. We compared 14 cases in which methylene injection was used with 14 cases from our records in which conventional investigation techniques were applied. The lymph node harvest differed highly significantly (p<0.001) between the two groups, with average numbers of 28+/-7 and 14+/-3 in the methylene blue group and the unstained group, respectively. The largest difference occurred in the size group 2-4 mm (191 vs 70 lymph nodes). In 6 cases in the unstained group additional embedding of fatty tissue was necessary to reach an adequate number of investigated lymph nodes. Methylene blue injection is a novel and highly effective method that will improve lymph node preparation in colorectal cancer.     

Overexpression of eIF3e is correlated with colon tumor development and poor prognosis

EIF3e is a component of the eukaryotic translation initiation factor 3 (eIF-3) complexes, which is an essential factor for initiation of protein synthesis in mammalian cells. Translational control plays key roles in the complex mechanism of cancer development and progression. However, the clinical significance of eIF3e in colon cancer remains to be elucidated. We analyzed the eIF3e expression in a tissue microarray (TMA), which contained 173 colon cancer tissues paired with adjacent normal mucosa and lymph node metastasis. The expression of eIF3e was significantly elevated in colon cancer tissues in comparison with those in adjacent normal mucosa (P < 0.001) and lymph node metastasis (P < 0.001). The high expression of eIF3e in colon cancer was significantly correlated with tumor size (P < 0.001), lymph node involvement (P < 0.001), distant metastasis (P < 0.001), clinical stage (P < 0.001), histopathologic classification (P < 0.001), and vessel invasion (P = 0.036). Univariate and multivariate analysis revealed that eIF3e is an independent prognosis factor for overall survival and disease-free survival in colon cancer. Down-regulation of eIF3e in vitro inhibited colon cancer cell proliferation, clonality and promoted cell apoptosis. Taken together, high eIF3e expression may contribute to tumor progression and predict poor prognosis in colon cancer.     

bFGF在恶性肿瘤中的表达及其临床病理意义

目的:检测临床常见恶性肿瘤(非小细胞肺癌、乳腺癌、结肠癌和黑色素瘤)组织中碱性成纤维细胞生长因子(b FGF)的表达情况,并分析其与恶性肿瘤临床病理学特征之间的相关性。方法:采用免疫组织化学SP技术检测208例原发性恶性肿瘤(肺癌68例,乳腺癌80例,结肠癌41例和黑色素瘤19例)石蜡包埋组织中b FGF蛋白的表达水平。结果:在肺癌中b FGF蛋白高表达多见于伴有淋巴结转移的低分化患者,与肿瘤原发灶大小、淋巴结受累、远处转移(TNM)分期呈正相关,且b FGF的表达对患者中位生存期无明显影响;在乳腺癌中,b FGF高表达多见于伴淋巴结转移的晚期患者;在结肠癌中b FGF蛋白表达多见于伴有区域淋巴结转移的中高分化患者;此外,在晚期有淋巴结转移的黑色素瘤患者中,b FGF蛋白呈高表达。结论:b FGF可能参与了临床常见恶性肿瘤的发生和演变过程,b FGF蛋白表达可能成为判断恶性肿瘤是否发生转移的有效参考指标之一。     

Size and histologic characteristics of lymph node material retrieved from tissue discarded after routine pathologic examination of lung cancer resection specimens

Redissection of discarded lung resection specimens after routine pathology examination reveals missed lymph node metastasis. We sought to determine if size can be used to grossly select lymph nodes for microscopic examination. This is a prospective cohort study of lymph nodes retrieved from discarded lung resection specimens. The association between size and histologic characteristics of retrieved material was compared by the Wilcoxon-Mann-Whitney test. We retrieved 1094 grossly ‘lymph node–like” tissue from 112 remnant lung resection specimens, of which 345 (32%) proved not to be lymph nodes and 71 (9%) of 749 lymph nodes had metastasis. Metastasis was present in discarded nodes in 26 (23%) of 112 patients. The non–lymph node tissue was significantly smaller than lymph nodes (P < .0001); lymph nodes with metastases were significantly larger than those without metastases (P < .0001). However, there was significant size overlap between the 3 types of grossly lymph node–like tissue. Thirty-two percent of nodes with metastasis were less than 1 cm; 15% of patients had at least 1 lymph node less than 1 cm with metastasis. The size difference between lymph nodes with and without metastasis is clinically unhelpful because of broad overlap. Size is insufficiently discriminatory and cannot be relied on to select materials for histologic examination. A third of grossly retrieved material was non–lymph node tissue. This probably occurs during routine pathologic examination and likely contributes to the low N1 lymph node count.