International Journal on Gastroenterology and Liver Disorders (IJGLD)

Mini Review Volume1-Issue1

Colon Cancer: Dietary Risk Factors and the Relevance of Gut Microbiota

Teresa Rubio-Tomás1,2

1Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Spain
2School of Medicine, University of Crete, Greece

*Corresponding author: Teresa Rubio-Tomás, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036, Barcelona, Spain, School of Medicine, University of Crete, 70013, Herakleion, Crete, Greece
Article History
Received: July 19, 2021 Accepted: July 26, 2021 Published: July 29, 2021
Citation: Rubio-Tomás T. Colon Cancer: Dietary Risk Factors and the Relevance of Gut Microbiota. Int J Gastroenterol Liver Dis. 2021;1(1):10‒11. DOI: 10.51626/ijgld.2021.01.00002

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Colon cancer is the third most common cause of cancer-derived death worldwide and the most common carcinoma of the digestive tract. The worldwide incidence is increasing, mainly due to the rise of its modifiable risk factors (i.e. are smoking, alcohol abuse, high intake of red and processed meat, low intake of fruits and vegetables, and high body fat content and obesity).

In this mini review I will offer a brief introduction of the risk factors of colon cancer and the relevance of microbiota alterations (i.e. dysbiosis). For deeper insights into this promising preventive, diagnostic and therapeutical option, I will refer to more exhaustive recently-published review articles.

Colon Cancer and its Risk Factors

Colon cancer, also known as colorectal cancer (CRC), is the third most common cause of cancer-derived death worldwide and the most common carcinoma of the digestive tract. The most frequent form of CRC is colon adenocarcinoma, but in here we offer a very general overview of CRC [1,2].

CRC occurrence is influenced by non-modifiable factors and modifiable factors, which contribute in a positive of negative way. The most prominent non-modifiable risk factors for the development of CRC are age, male gender, type 2 diabetes, inflammatory bowel disease and hereditary factors, while modifiable (non-heritable) risk factors are smoking, alcohol abuse, high intake of red and processed meat, low intake of fruits and vegetables, and high body fat content and obesity [3,4]. With respect to factors that protect the organism against CRC tumorigenesis, it is important to highlight that they are mainly modifiable factors, including physical activity and regular consumption of dietary fiber, whole grains, nuts, fish, vitamins (D and C, among others), dairy products and enough quantities of calcium [5-8]. Some therapies, such as aspirin or non-steroidal anti-inflammatory drugs (i.e. ibuprofen), statins (cholesterol-lowering drugs) and menopausal hormone therapy, are also considered to be protective against CRC [9-11].

CRC is clearly related to Western diet and its incidence can be considered a marker of socioeconomic development [12]. Even though temporal patterns of incidence and mortality are very variable among countries [2], the global burden of CRC is expected to increase in the next years [13]. Indeed, the World Health Organization estimates that around 1.1 million patients will die from CRC in 2030 [14,15].


Healthcare costs continue to rise in the United States, and yearly estimates from 2018 account for 11.0 million colonoscopies, 6.1 million esophagogastroduodenoscopies (EGD), 313,000 flexible sigmoidoscopies, 178,400 upper endoscopic ultrasound examinations, and 170,000 endoscopic retrograde cholangiopancreatography (ERCP) procedures [1]. Nationwide, annual expenditures on gastrointestinal diseases account for as much as $135.9 billion [1]. The most up to date estimates from 2012 place indirect and direct costs from outpatient endoscopic procedures at $32.4 billion annually [2]. Gastrointestinal procedures represent the largest percentage of Medicare claims at ambulatory surgery centers, and this trend is likely to continue [3].

As the demand for endoscopic procedures continues to grow, it is necessary to evaluate our current systems in search of opportunities to improve time and cost efficiency. Improving efficiency is imperative to improving quality of care for patients. The National Academy of Sciences Institute of Medicine includes efficiency as one of their key elements of quality care delivery, striving for a “continuous decrease in waste” [4]. Major challenges in achieving efficiency revolve around the appropriate use of limited resources including staff, facilities, equipment, and time [5]. Key targets to improve efficiency in the endoscopy unit include pre- and post-procedure wait time, first case start time, and scheduled procedure time [6]. Certain targets such as procedure time are more difficult to adjust in comparison to more malleable factors such as turnover time. With improved scheduling and estimates of procedure time, a more accurate plan for each day can be created.

Each endoscopy center faces varied challenges and bottlenecks in their workflow. Kaushal et al. found that their endoscopy unit bottlenecks were delays in the pre- and post-procedure recovery rooms, while room turnaround time (TAT) and room-per-endoscopist ratio were not driving parameters in efficiency [7]. In contrast, Yang et al. [8] identified TAT as a cause for their unit’s decreased efficiency [8]. Decreasing room TAT is a common target to improve the timing and volume of procedures that can be completed9. Actual procedure times are longer than the scheduled procedure times at these centers, and this is likely a common occurrence in other endoscopy centers [7-9]. Such varied findings highlight the various processes in which each center approaches the issue of endoscopy unit efficiency. Among other studies, implicating factors include personnel utilization, patient scheduling, procedure delays, sedation, and recovery room delays [10]. Academic medical centers regularly have delays between 30-50% of all endoscopic procedures. Common causes of delays include physician unavailability and patient flow processes that include registration time, admission, transportation, and scheduling [8,11].

Different strategies have been described for improving endoscopy unit efficiency. For example, some centers utilize a two-rooms-per endoscopist model. However, in many tertiary-care hospitals, space is at a premium [12]. While training providers to reduce procedure time seems like a viable strategy, Zamir et al. [9] found an over three-fold variation in procedure volume score among their endoscopists that is difficult to control from a systems-based approach [9]. The variability in procedure volume score, and likely procedure time, may be attributed to numerous factors such as endoscopist experience with specific procedures, time in practice, and advanced training. These factors are challenging to alter by changing a scheduling system or adding additional rooms to a unit. There may also be causes inherent to the procedures themselves that introduce variation, such as rare cases, altered anatomy, high risk procedures, or the use of intricate equipment.

Uncertainty remains in the search for the best way to improve efficiency in endoscopy units. The answer most likely varies due to individual factors unique to each site. The aim of this study is twofold: to identify bottlenecks in the staff workflow and to quantify differences between scheduled and actual procedure times at our high-volume tertiary care endoscopy center. The hope is not only to improve the quality of care for our patients, but to add to the growing body of data on endoscopy unit efficiency and provide a framework for future improvements. Improved efficiency enhances patients’ experiences, improves employee workplace satisfaction, and allows more patient access to necessary endoscopic procedures.

The Gut Microbiota and Colon Cancer

The term dysbiosis is commonly referred to alterations in the composition of the microorganisms living in the intestine (i.e. gut microbiota). Dysbiosis is linked to CRC risk factors, such as obesity [16], and to the CRC oncogenic process itself [17], and can be reversed [18]. Changes of microbiota are present even in precancerous CRC lesions [19]. In this sense, specific dietary interventions, including pre- and probiotics, have been suggested since diet-induced modifications of the gut microbiota could prevent or improve the prognosis of CRC [20,21].

Conclusion and Further Directions

In summary, although the role of diet in CRC development was already known, the microbiota provides a targetable and measurable way of understanding the impact of dietary interventions in the prevention and management of CRC [22].


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