(Author)
Abstract
Diabetes is a disease in which glucose levels are elevated to a huge amount in the body. More than 25 million people having 20 years of age and more than 20 years in the U.S. are found to have diabetes that is three times more than the number of patients in 1980. Scientists have found that diabetes can result in increased chances of developing colonic cancer equally in men and women (Sun & Kashyap, 2011). Different mechanisms such as hyperinsulinemia, insulin resistance, central adiposity, increased growth factors, hyperglycemia, and several luminal factors have been proposed that are involved in the development of colonic cancer as a result of diabetes. Diabetes and cancer have many common lifestyle-related risk factors. These factors are non-modifiable risk factors such as age, gender, race/ethnicity, and genetic factors, and modifiable risk factors such as poor diets, obesity, smoking, alcohol intake, and physical activity (Giovannucci et al., 2010). Working on these factors can help in prevention of the cancer. Further studies are needed to find the exact mechanism for better prevention and therapy of cancer resulting from diabetes.
Keywords: diabetes, cancer, colon cancer
Introduction
Diabetes is a polygenic type of disease that is characterized by an unusually increased amount of glucose in the blood. It has been found that over 25 million adults, who are older than 20 years, in the United State have diabetes. This number is over three times to that of the number of patients in 1980. Diabetes is considered as a serious problem because it can result in a number of other potentially harmful disturbances such as nerve damage, heart disease, and stroke. Now scientists have found that type-2 diabetes can also raise the risk of producing colon cancer. It has been reported that patients of type-2 diabetes have 38% higher chances of developing colon cancer. Moreover, chances of death are more in patients of colon cancer, who are also the patients of diabetes, as compared to patients, who are only the patients of colon cancer (Mendes, 2014). Researchers have found that patients of diabetes have more chances of developing cancer in the proximal colon as compared to the distal colon (Jarvandi, Davidson & Schootman, 2013). Some studies are showing that men are at increased risk of developing colorectal cancer than women, whereas other studies are showing that both genders are equally at risk (Sun & Kashyap, 2011).
Pathophysiology of diabetes related colonic cancer
Some mechanisms have been proposed by scientists, which are considered to have a role in the development of colonic cancer from diabetes. Usually, patients of diabetes are obese and have the habit of living sedentary lives resulting in hyperinsulinemia - increased amount of insulin in the blood of the patients. It has been proposed that secondary hyperinsulinemia and insulin resistance – a process in which cells of the body don’t respond to the actions of insulin –result in an environment in the colon that causes the growth and development of cancer. Mitogenic effect of insulin is thought to play a role through binding to the insulin-like growth factor-1 (IGF 1) receptor in the growth of cancer. According to another postulate, there is an unregulated insulin receptor signaling resulting in proliferative and anti-apoptotic processes.
Researchers have also reported that central adiposity can also result in insulin resistance resulting in metabolic disturbances in diabetes. Adipose tissue-related free fatty acids, cytokines, and other vascular factors secreted from the visceral compartment can result in insulin resistance, glucose related problem, lipid disturbances, and low level of inflammation that are collectively responsible for the development and progression of cancer (Sun & Kashyap, 2011).
Diabetes patients also have increased level of growth factors that are involved in the growth of cells including cancer cells, and their movement to other parts of the body.
According to another hypothesis, too much sugar in the blood, i.e. hyperglycemia, and chronic inflammation as a result of diabetes are linked to the development of colonic cancer and the spread of cancer. Hyperglycemia results in the increased oxidative stress that is also carcinogenic. This oxidative stress would harm DNA that is considered to be among the first steps in cancer development, progression, and spread to other areas of the body.
Researchers are of opinion that systemic factors alone would not be able to explain the link between diabetes and colorectal cancer. Luminal factors are also involved along with systemic disturbances in the development of such association. It has been proposed that variations in bile acid metabolism, prolonged bowel transit time, compositional variations in gut microbiota, and decrease in gut mucosal layer, either alone or in combination, could result in the development of cancer (Jarvandi et al., 2013).
Factors responsible for diabetes and colon cancer
Diabetes and cancer have many common lifestyle-related risk factors. These risk factors are non-modifiable risk factors such as age, gender, race/ethnicity, and genetic factors, and modifiable risk factors such as poor diets, obesity, smoking, alcohol intake, and physical activity (Giovannucci et al., 2010). Typical Western dietary patterns are found to be related to increased chances of cancer and diabetes. Researchers have found that patients of diabetes with less favorable diet have approximately 60% more chances of developing colorectal cancer than normal people. On the other hand, patients of diabetes with favorable diet have 20% more chances of developing colorectal cancer than normal people with good diet. Researchers have reported that decreased intake of milk, fruits, and vegetables, and increased intake of red and processed meat could increase the chances of distal colon cancer. On the other hand, fat is found to have a link with proximal colon cancer probably due to interaction with bile (Jarvandi et al., 2013). Diets with decreased fiber can also increase the chances of cancer in type 2 diabetes. Among other common factors are cirrhosis and hepatitis C viral infection. Studying the common factors responsible for diabetes and cancer can help in developing preventive and therapeutic strategies.
Prevention of diabetes and colonic cancer
Colon cancer is found to be the third most commonly occurring cancer in the U.S. Fortunately; it is also among the most preventable types of cancer (Mendes, 2014). Scientists are of opinion that preventing the development of type-2 diabetes can help in preventing the development of colon cancer. Patients of diabetes have to go through the process of cancer screenings according to their age and gender as recommended by health care professionals. This can help in hindering the production and development of cancer as a result of diabetes. Some important ways to prevent the development of type-2 diabetes include:
- Healthful diets,
- Limiting or stopping the use of the diet that is high in red and/or processed meats,
- Proper exercise and regulating healthy physical activities,
- Maintaining healthy weight,
- Stopping the tobacco use and alcohol intake.
Concluding Remarks
Diabetes is considered as 12th most important cause of death in the world and cancer is the 2nd leading cause of death that is why it is important to stop the growth of cancer as a result of diabetes. In this regard, explanation of exact mechanisms behind the development of cancer due to diabetes can help. Although various mechanisms have been proposed in the development of cancer as a result of diabetes but further investigations are required to find the exact mechanism. It has been reported that patients of type-1 diabetes have less chances of developing cancer as compared to the patients with type-2 diabetes, but the evidence of risk in comparison with the general population requires further studies.
Research has shown that patients of type-2 diabetes who are on insulin therapy for over a year have more chances of developing colorectal cancer. Although this research shows that increased level of insulin is responsible for increased risk of cancer but patients should not stop taking insulin instead they have to follow screening guidelines to detect colorectal cancer in the early stages.
References
Giovannucci, E., Harlan, D. M., Archer, M. C., Bergenstal, R. M., Gapstur, S. M., Habel, L. A., . . . Yee, D. (2010). Diabetes and cancer: a consensus report. [Consensus Development Conference Research Support, Non-U.S. Gov't]. Diabetes Care, 33(7), 1674-1685. doi: 10.2337/dc10-0666
Jarvandi, S., Davidson, N. O., & Schootman, M. (2013). Increased risk of colorectal cancer in type 2 diabetes is independent of diet quality. PloS one, 8(9), e74616.
Mendes, E. (2014). Diabetes and Colon Cancer: An Emerging Link. Retrieved from http://www.cancer.org/research/acsresearchupdates/coloncancer/diabetes-and-colon-cancer-an-emerging-link
Sun, G., & Kashyap, S. R. (2011). Cancer risk in type 2 diabetes mellitus: metabolic links and therapeutic considerations. Journal of nutrition and metabolism, 2011.
