BACKGROUND AND AIMS The impact of recurrent low-grade dysplasia (LGD) on the risk of advanced neoplasia (high-grade dysplasia and colorectal cancer) in inflammatory bowel disease (IBD) patients is unknown. In addition, it is unclear how a neoplasia-free period after index LGD impacts this risk. We aimed to determine whether recurrent LGD is a risk factor for advanced neoplasia development and to evaluate the impact of a neoplasia-free time period after initial LGD diagnosis on the advanced neoplasia risk. METHODS This is a nationwide cohort study using data from the Dutch National Pathology Registry to identify all IBD patients with LGD and ≥1 follow-up colonoscopy between 1991 and 2010 in the Netherlands. Follow-up data were collected until January 2016. We compared the cumulative advanced neoplasia incidence between patients with and without recurrent LGD at first follow-up colonoscopy using log-rank analysis. We subsequently studied the impact of a neoplasia-free period after initial LGD on the advanced neoplasia incidence. RESULTS We identified 4284 IBD patients with colonic LGD with a median follow-up of 6.4 years. Recurrent LGD was a risk factor for advanced neoplasia (hazard ratio, 1.66; 95% confidence interval, 1.22-2.25; P = .001). A neoplasia-free period of at least 3 years after LGD protected against advanced neoplasia. CONCLUSIONS Recurrent LGD at follow-up colonoscopy after initial LGD was a risk factor for advanced neoplasia. A neoplasia-free period of at least 3 years after initial LGD was associated with a reduced subsequent risk of advanced neoplasia.

中文翻译：

---

反复出现低度不典型增生的炎症性肠病患者发生高度不典型增生和结直肠癌的风险增加。

背景和目的炎症性肠病（IBD）患者反复发作的低度发育不良（LGD）对晚期肿瘤（高度发育不良和结直肠癌）风险的影响尚不清楚。此外，尚不清楚指标LGD后无瘤形成期如何影响该风险。我们旨在确定复发性LGD是否是晚期肿瘤形成的危险因素，并评估LGD最初诊断后无瘤形成时间段对晚期肿瘤形成风险的影响。方法这是一项全国性队列研究，使用荷兰国家病理登记局提供的数据，鉴定了1991年至2010年之间荷兰的所有LGD≥1例结肠镜检查的IBD患者。随访数据收集至2016年1月。我们使用对数秩分析比较了首次随访结肠镜检查中有和没有复发LGD的患者之间累积的晚期赘生物发生率。我们随后研究了初始LGD后无瘤形成期对晚期肿瘤形成发生率的影响。结果我们确定了4284名IBD结肠LGD患者，中位随访时间为6.4年。复发性LGD是晚期肿瘤的危险因素（危险比1.66； 95％置信区间1.22-2.25； P = .001）。LGD至少有3年的无瘤形成期，可防止晚期瘤形成。结论初次LGD术后在结肠镜检查中复发LGD是晚期肿瘤的危险因素。初始LGD后至少3年的无瘤形成期与随后的晚期瘤形成风险降低有关。