Toxigenic gut bacteria, diet and colon carcinogenesis

Challenges around diagnosis of early onset colorectal cancer, and the case for screening

BACKGROUND

Colorectal cancer (CRC) is the third most diagnosed cancer in the world, with an estimated 1.93 million cases diagnosed in 2020. While the overall CRC incidence in many countries is falling there has been a dramatic increase in CRC in those aged under 50 (early onset colorectal cancer, EOCRC). The reason for this increase in EOCRC is unknown. As the best predictor of survival is stage at diagnosis, early diagnosis is likely to be beneficial and population screening may facilitate this.

METHODS

A narrative review of the literature was undertaken.

RESULTS

Improving time to diagnosis in symptomatic patients is beneficial. However, by the time symptoms develop, over a third of patients already have metastatic disease. Screening asymptomatic patients (with Faecal Immunochemical test (FIT) and colonoscopy) has been proved to be effective in older patients (>60 years). In younger populations, the decreasing incidence rates of CRC previously made cost effectiveness, compliance and therefore benefit questionable. Now, with the increasing incidence of CRC in those under 50 years of age, modelling suggests screening with FIT and colonoscopy is cost effective from 40 years of age. There is evidence that some countries screening below 50 have prevented the rise in EOCRC incidence. Additionally the use of new and novel non-invasive biomarkers may also be able to improve the accuracy of screening asymptomatic patients.

CONCLUSION

Diagnosis of EOCRC once symptoms develop is often too late, and screening patients from age 40 is the best way to improve outcomes in this group.

Biomarkers to Detect Early-Stage Colorectal Cancer

Colorectal cancer is a leading cause of mortality worldwide. The high incidence and the acceleration of incidence in younger people reinforces the need for better techniques of early detection. The use of noninvasive biomarkers has potential to more accurately inform how patients are prioritised for clinical investigation, which, in turn, may ultimately translate into improved survival for those subsequently found to have curable-stage CRC. This review surveys a wide range of CRC biomarkers that may (alone or in combination) identify symptomatic patients presenting in primary care who should be progressed for clinical investigation.

Gut Microbiota: Influence on Carcinogenesis and Modulation Strategies by Drug Delivery Systems to Improve Cancer Therapy

Gut microbiota have close interactions with the host. It can affect cancer progression and the outcomes of cancer therapy, including chemotherapy, immunotherapy, and radiotherapy. Therefore, approaches toward the modulation of gut microbiota will enhance cancer prevention and treatment. Modern drug delivery systems (DDS) are emerging as rational and promising tools for microbiota intervention. These delivery systems have compensated for the obstacles associated with traditional treatments. In this review, the essential roles of gut microbiota in carcinogenesis, cancer progression, and various cancer therapies are first introduced. Next, advances in DDS that are aimed at enhancing the efficacy of cancer therapy by modulating or engineering gut microbiota are highlighted. Finally, the challenges and opportunities associated with the application of DDS targeting gut microbiota for cancer prevention and treatment are briefly discussed.