Over the past several decades, the incidence of early-onset colorectal cancer (EOCRC; in patients <50 years old) has increased at an alarming rate. Although robust and scientifically rigorous epidemiological studies have sifted out environmental elements linked to EOCRC, our knowledge of the causes and mechanisms of this disease is far from complete. Here, we highlight potential risk factors and putative mechanisms that drive EOCRC and suggest likely areas for fruitful research. In addition, we identify inconsistencies in the evidence implicating a strong effect of increased adiposity and suggest that certain behaviours (such as diet and stress) might place nonobese and otherwise healthy people at risk of this disease. Key risk factors are reviewed, including the global westernization of diets (usually involving a high intake of red and processed meats, high-fructose corn syrup and unhealthy cooking methods), stress, antibiotics, synthetic food dyes, monosodium glutamate, titanium dioxide, and physical inactivity and/or sedentary behaviour. The gut microbiota is probably at the crossroads of these risk factors and EOCRC. The time course of the disease and the fact that relevant exposures probably occur in childhood raise important methodological issues that are also discussed.

中文翻译：

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早发性结直肠癌：初步线索和当前观点。

在过去的几十年中，早发性结直肠癌（EOCRC；<50 岁患者）的发病率以惊人的速度增加。尽管强有力且科学严谨的流行病学研究已经筛选出与 EOCRC 相关的环境因素，但我们对这种疾病的原因和机制的了解还远未完成。在这里，我们强调了推动 EOCRC 的潜在风险因素和推定机制，并提出了富有成效的研究的可能领域。此外，我们发现证据中的不一致之处暗示了肥胖增加的强烈影响，并表明某些行为（例如饮食和压力）可能会使非肥胖和其他方面健康的人面临患这种疾病的风险。审查关键风险因素，包括饮食的全球西化（通常涉及大量摄入红肉和加工肉类、高果糖玉米糖浆和不健康的烹饪方法）、压力、抗生素、合成食用染料、味精、二氧化钛以及缺乏身体活动和/或久坐不动行为。肠道微生物群可能处于这些危险因素和 EOCRC 的十字路口。疾病的时间进程以及相关暴露可能发生在儿童时期这一事实提出了重要的方法论问题，这些问题也进行了讨论。