What is the link between diabetes and cancer?

Diabetes and cancer are serious, multifactorial, complex and often co-morbid conditions. Potential biological links between the two are not fully understood, but according to a collaborative study by the American Diabetes Association^[1] and the American Cancer Society, patients with type 2 diabetes are at greater risk of developing certain types of cancer than those without it. The relative risks associated with diabetes are greatest (about two times or more) for cancers of the liver, pancreas, endometrium, and smaller (about 1,2 to 1,5 times) for cancers of the colon, rectum, breast, and Bladder.

Both pathologies have identical risk factors:

1. Smoking. Nicotine has a negative effect on all organs and systems, contributes to a decrease in immunity and endurance of the body. And cigarette smoke contains carcinogens that damage healthy cells and then turn them into cancer.
2. Obesity contributes to the restructuring of certain metabolic and hormonal processes, which increases the likelihood of the appearance and growth of malignant neoplasms.
3. Age over 40 years. It is in adulthood that the consequences of bad habits make themselves felt. In this category of people, obesity, high blood pressure and other potentially dangerous conditions are much more common.
4. The predominance of fatty, smoked, fried, sweet and spicy foods, semi-finished products in the diet, frequent overeating.
5. Lack of movement – people who lead a sedentary lifestyle are more likely to have high blood sugar.

Under the influence of these factors, anyone can develop a tumor, but in people with diabetes, the activity of the immune system is reduced, which makes the body less able to resist the effects of bacteria and viruses. Due to frequent collisions with them, cell DNA can be damaged, causing mutations, one of which can become the starting point for tumor development. Such mutations can also cause tumor resistance to chemicals, complicating treatment.

On the Internet, you can find articles that say that high blood sugar provokes cancer, so you should completely give up sweets. Indeed, absolutely all cells of the body feed on glucose, including abnormal ones. In the 50s, the German biochemist Otto Warburg linked glucose to cancerous tumors. When sugar is oxidized in the body, a large amount of energy is released, which accelerates the division of cancer cells and the spread of metastases (later this process was called the Warburg effect). Glucose creates a kind of vicious circle – the tumor consumes carbohydrates, as a result of which it grows and, as a result, needs even more of them. This effect is used in oncology, for example, to detect tumors. At the same time, there is no evidence of a direct effect of glucose on the occurrence of cancer, which means that it is not required to completely exclude sweets. However, it is important to know the measure – excessive consumption of sweets can lead to obesity, which, according to a study by the American Cancer Society^[2], provokes hormonal disorders, and those, in turn, trigger the development of various types of cancer.

Diagnostics and treatment of cancer in diabetes mellitus

What cancer tests are undesirable in diabetes? Only positron emission tomography (PET CT) is contraindicated, and then only against the background of decompensation of diabetes mellitus (if the glucose level exceeds 12-13 mmol/l). Since the drug administered during this examination contains a high concentration of glucose, this diagnosis is not carried out with hyper- and hypoglycemia (high and low blood sugar levels, respectively). With hyperglycemia, PET CT can provoke a hyperglycemic coma, with hypoglycemia it does not make sense, since all the glucose will be absorbed by tissues that are starving for it, and the whole body will emit a glow. This problem can be solved with the help of an endocrinologist, who will adjust the dose of the antidiabetic agent and the mode of its administration. If the examination requires restriction of food intake and is performed on an empty stomach (for example, ultrasound of certain internal organs or endoscopy of the stomach), difficulties may arise, but in general there are no contraindications.

The treatment of oncological disease against the background of diabetes requires a special approach, taking into account the stages and severity of both diseases, which coexist in tandem. The use of chemotherapy and radiation therapy is not always effective. During chemotherapy, patients are prescribed steroid drugs that cause the blood glucose level to rise above the acceptable limit, which complicates the course of the disease and reduces the chances of a successful result. Also, treatment is complicated by the fact that diabetes often affects the kidneys, and many chemotherapy drugs are excreted through them. Renal failure (and, as a result, delayed elimination of chemotherapy drugs) can lead to serious consequences, including damage to the cardiovascular and nervous systems, since some chemotherapy drugs have increased cardiotoxicity. Elevated glucose levels make nerve fibers more brittle and prone to destruction, and the heart and blood vessels more sensitive to the effects of drugs. Chemotherapy accelerates the development of these changes by affecting the cells of the central nervous system. Radiation therapy is an alternative to chemotherapy, but it also raises blood sugar levels.

On an individual basis, the specialist determines the optimal course of treatment and decides what is best for the patient: reduce the dose of chemotherapy or be ready to correct the increased glucose level. Since diabetic patients have generally reduced immunity, a sharp decrease in the number of leukocytes after chemotherapy leads to complicated infectious diseases. After surgery, bleeding from vessels affected by diabetes, inflammation, or acute renal failure may occur.

Compensation for diabetes under the supervision of an endocrinologist is no less important than antitumor treatment. In order to reduce the likelihood of cancer moving to the terminal stage and improve the prognosis of treatment, it is necessary to control the level of sugar, and, if necessary, adjust glucose-lowering therapy in time until diabetes compensation is achieved. This can be achieved under a number of conditions (in addition to taking hypoglycemic drugs). An important factor is a diet low in simple carbohydrates. The basis of the diet should be animal proteins (meat, fish, poultry, seafood, etc.), and foods high in simple carbohydrates should be excluded (sweet fruits, cereals, confectionery, etc.). Eating fried foods is prohibited, as well as smoking. By following these guidelines, you can maintain acceptable blood sugar levels.

An important factor for improving the patient’s condition is also dosed physical activity.

In general, in order to reduce the likelihood of developing cancer in diabetes mellitus or to detect it at an early stage, glucose levels and weight should be monitored, as well as regular cancer screening. It is also necessary to give up smoking and not to abuse alcohol without fail.

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