近年来，小肾细胞癌（sRCC）的发病率大幅增加。考虑到sRCC具有异质生物学，如果能够预测sRCC的转移，特定的临床或病理参数将具有临床意义。在本研究中，我们旨在评估有无转移的病理T1a RCC（pT1a RCC）的临床病理因素，以探究预测转移的因素。本研究纳入了198例在1985年至2017年期间，在日本肾癌学会下属的十五家机构进行根治性或部分肾切除手术的pT1a RCC患者。分析了包括年龄、性别、肿瘤大小、肿瘤侧位、组织学亚型、组织学核级、淋巴血管浸润和组织生长模式在内的临床病理参数。Fuhrman分级3或4级的肿瘤和浸润性肿瘤生长模式在转移患者中显著高于非转移患者。pT1a RCC患者中同步转移最常见的部位为骨骼（65.4%），而术后间歇性转移患者中最常见的部位为肺（46.2%）。组织生长模式和核级对于预测pT1a RCC的转移至关重要，建议对这类患者进行长期的仔细随访。版权所有©2023年国际抗癌研究学会（George J. Delinasios博士），保留所有权利。

Small renal cell carcinomas (sRCC) have drastically increased in recent years. Considering that sRCC have heterogeneous biology, it would be clinically relevant if specific clinical or pathological parameters could predict sRCC metastasis. In the present study, we aimed to assess the clinicopathological factors of pathologic T1a RCC (pT1a RCC) with or without metastasis to explore factors predicting metastasis.The present study included 198 patients with pT1a RCC who underwent radical or partial nephrectomy at fifteen institutions belonging to the Japanese Society of Renal Cancer, between1985 and 2017. Clinicopathological parameters, including age, sex, tumour size, tumour side, histological subtype, histological nuclear grade, lymphovascular invasion, and histological growth patterns, were analysed.Fuhrman grade 3 or 4 tumours and infiltrative tumour growth patterns were significantly higher in patients with metastasis than in those without. The most common site of synchronous metastasis was the bone in patients with pT1a RCC (65.4%), whereas for patients with post-surgery metachronous metastasis (46.2%), it was the lungs.Histological growth pattern and nuclear grade are vital for predicting metastasis in pT1a RCC, suggesting careful long-term follow-up for such patients.Copyright © 2023 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.