Current Colorectal Cancer Reports最新文献

Purpose of the review: To summarize the current evidence on the most important dietary and lifestyle factors in colorectal carcinogenesis during different stages of a lifetime with special emphasis on studies investigating exposure during childhood, adolescence and young adulthood.

Recent findings: A number of studies showed that independent of adult obesity, higher body fatness during childhood, adolescence and young adulthood is associated with risk of colorectal cancer later in life. In one large cohort study, the Nurses' Health Study II, adherence to a western pattern diet during adolescence was associated with higher risk of advanced adenoma. The current evidence relating consumption of individual foods and nutrients as well as physical activity during early life to colorectal cancer is sparse and less consistent, at least in part due to limitations in study design, such as sample size, limited data on potential confounders or lack of a validated dietary assessment instrument.

Summary: As colorectal carcinogenesis is a long process and can take up to several decades to develop, early life risk factors may also be etiologically relevant. The recent rise in early-onset colorectal cancer incidence and mortality in the US, i.e., in individuals younger than 55 years at diagnosis, strongly supports that early life risk factors may influence colorectal carcinogenesis. Considering that the majority of colorectal cancers are preventable, there is an urgent need for well-designed investigations on the role of diet and lifestyle factors throughout the life course and risk of colorectal cancers.

Purpose of review: Colorectal cancer liver metastasis is a major clinical problem, and surgical resection is the only potentially curative treatment. We seek to discuss various liver-directed therapy modalities and explore their roles in the evolving realm of treatment strategies for metastatic colorectal cancer.

Recent findings: Clinical outcomes for patients with colorectal cancer liver metastases have improved as more patients undergo potentially curative resection and as the armamentarium of systemic treatment and liver-directed therapies continues to expand. Liver-directed therapies have been developed as adjuncts to improve resectability, employed in the adjuvant setting to potentially reduce local recurrence rates, and utilized in the palliative setting with the aim to improve overall survival.

Summary: Ongoing research is expected to validate the role of these evolving therapeutic options, and determine how best to sequence and when to apply these therapies.

Purpose of review: Pathological complete response is seen in approximately one fifth of rectal cancer patients following neoadjuvant chemoradiation. Since these patients have excellent oncological outcomes, there has been a rapidly growing interest in organ preservation for those who develop a clinical complete response. We review the watch-and-wait strategy and focus on all aspects of this hot topic, including who should be considered for this approach, how should we identify treatment response and what are the expected outcomes.

Recent findings: The major challenges in interpreting the data on watch-and-wait are the significant heterogeneity of patients selected for this approach and of methods employed to identify them. The evidence available comes mostly from retrospective cohort studies, but has shown good oncological outcomes, including the rate of successful salvage surgery, locoregional control and overall survival.

Summary: There is currently not enough and not robust enough evidence to support watch-and-wait as a standard approach, outside a clinical trial, for patients achieving clinical complete response following neoadjuvant chemoradiation. Furthermore, there is a lack of data on long-term outcomes. However, the results we have so far are promising, and there is therefore an urgent need for randomised control studies such as the TRIGGER trial to confirm the safety of this strategy.

Purpose of review: Colorectal cancer (CRC) is a global public health problem, with an estimated 1.4 million cases diagnosed worldwide in 2012. Evidence suggests that diet may be important for primary prevention.

Recent findings: The 2017 WCRF/AICR Continuous Update Project on colorectal cancer concluded that there is convincing evidence linking several individual dietary factors with CRC risk but the evidence for dietary patterns was limited and inconclusive. Also, previous reviews and meta-analyses have not critically synthesized various dietary patterns. This review synthesized data from dietary patterns studies over a 17-year period from 2000 to 2016.

Summary: We included 49 studies (28 cohort and 21 case-control) that examined the association of index-based and empirically-derived dietary patterns and CRC risk. A synthesis of food group components comprising the different index-based and empirically-derived patterns revealed two distinct dietary patterns associated with CRC risk. A "healthy" pattern, generally characterized by high intake of fruits and vegetables, wholegrains, nuts and legumes, fish and other seafood, milk and other dairy products, was associated with lower CRC risk. In contrast, the "unhealthy" pattern, characterized by high intakes of red meat, processed meat, sugar-sweetened beverages, refined grains, desserts and potatoes was associated with higher CRC risk. It is notable that the number of food groups, the intake quantity, the exact types of foods in each food group, differed between populations, yet the two dietary patterns remained consistent across regions, especially in empirically-derived patterns, an indication of the high reproducibility of these patterns. However, findings for CRC risk in both index-based and empirically-derived patterns, differed by sex, with stronger associations among men than women; study design, a higher proportion of case-control studies reported significant findings compared to prospective studies. Consuming a dietary pattern high in fruits and vegetables and low in meats and sweets is protective against CRC risk. However, important questions remain about mechanisms underlying differences by sex; life-course timing of exposure to dietary patterns; interaction of dietary patterns with the microbiome or with lifestyle factors including physical activity; and elucidation of subsite differences.

Diet plays an important role in the development of colorectal cancer. Emerging data have implicated the gut microbiota in colorectal cancer. Diet is a major determinant for the gut microbial structure and function. Therefore, it has been hypothesized that alterations in gut microbes and their metabolites may contribute to the influence of diet on the development of colorectal cancer. We review several major dietary factors that have been linked to gut microbiota and colorectal cancer, including major dietary patterns, fiber, red meat and sulfur, and obesity. Most of the epidemiologic evidence derives from cross-sectional or short-term, highly controlled feeding studies that are limited in size. Therefore, high-quality large-scale prospective studies with dietary data collected over the life course and comprehensive gut microbial composition and function assessed well prior to neoplastic occurrence are critically needed to identify microbiome-based interventions that may complement or optimize current diet-based strategies for colorectal cancer prevention and management.