BACKGROUND While the management of nonmetastatic and oligometastatic rectal cancer has rapidly evolved over the last few decades, many grey areas and highly debated topics remain that foster significant variation in clinical practice. We aimed to identify controversial points and evidence gaps in this disease setting by systematically comparing recommendations from national and international clinical guidelines. METHODS Twenty-six clinical questions reflecting practical challenges in the routine management of nonmetastatic and oligometastatic rectal cancer patients were selected. Recommendations from the ESMO, NCCN, JSCCR, Australian and Ontario guidelines were extrapolated and compared using a 4-tier classification system (i.e., identical/very similar, similar, slightly different, different). Overall agreement between guidelines (i.e., substantial/complete disagreement, partial disagreement, partial agreement, substantial/complete agreement) was assessed for each clinical question and compared against the highest level of available evidence by using the χ2 statistic test. RESULTS Guidelines were in substantial/complete agreement, partial agreement, partial disagreement, and substantial/complete disagreement for 8 (30.8%), 2 (7.7%), 7 (26.9%), and 9 (34.6%) clinical questions, respectively. High level of evidence supported clinical recommendations in 3/10 cases (30%) where guidelines were in agreement and in 10/16 cases (62.5%) where guidelines were in disagreement (χ2 = 2.6, p = 0.106). Agreement was frequently reached for questions regarding diagnosis, staging, and radiology/pathology pro-forma reporting, while disagreement characterised most of the treatment-related topics. CONCLUSIONS Substantial variation exists across clinical guidelines in the recommendations for the management of nonmetastatic and oligometastatic rectal cancer. This variation is only partly explained by the lack of supporting, high-level evidence.

中文翻译：

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通过比较临床指南的建议，可以发现直肠癌治疗中的灰色区域和证据空白。

背景技术尽管在过去的几十年中，非转移性和少转移性直肠癌的管理已迅速发展，但仍然存在许多灰色地带和备受争议的话题，这些都促进了临床实践的重大变化。我们旨在通过系统地比较来自国家和国际临床指南的建议来确定这种疾病背景下的争议点和证据差距。方法选择26个临床问题，这些问题反映了非转移性和少转移性直肠癌患者常规治疗中的实际挑战。使用4层分类系统（即，相同/非常相似，相似，略有不同，不同）对ESMO，NCCN，JSCCR，澳大利亚和安大略省指南中的建议进行了推断和比较。指南之间的总体协议（即，评估每个临床问题的基本/完全不同意见，部分不同意，部分同意，部分/基本同意，基本/完全同意），并使用χ2统计检验将其与可用证据的最高水平进行比较。结果指南分别有8个（30.8％），2个（7.7％），7个（26.9％）和9个（34.6％）临床问题处于基本/完全同意，部分同意，部分不同和基本/完全不同的状态。较高的证据支持3/10例（30％）的指导意见一致的临床建议和10/16例（62.5％）的指导意见不一致的临床建议（χ2= 2.6，p = 0.106）。关于诊断，分期以及放射学/病理学形式报告的问题经常达成共识，而大多数治疗相关主题均存在分歧。结论在针对非转移性和少转移性直肠癌的治疗建议中，整个临床指南存在很大差异。缺乏支持的高级证据只能部分解释这种差异。