Diabetes and cancer are two diseases that impact overall global health conditions. Epidemiological evidence reported that diabetic patients often have a higher cancer risk than healthy individuals. There are multiple subtypes in both of these chronic disease conditions. Broadly diabetes has two subtypes, type 1 and type 2, whereas, cancer subdivision depends upon anatomical regions like lung cancer, breast cancer, pancreatic cancer, etc. However, leukemia, lymphoma, and other cancers are further subdivided.
Both type 2 diabetes and cancer have some common lifestyle risk factors. But the exact relationship between these two disease conditions is not completely understood yet. Hypothetical explanation stated that medicines used to control hyperglycemia may play a role in cancer risk reduction and enhancement. In clinical findings, diabetes and cancer findings within the same individual are a more common incidence.
Diabetic male individuals often have prostate cancer. The relative risk of liver, pancreas, and endometrium cancers is higher compared to colon, rectum, breast, and bladder cancer incidences associated with diabetes. However, the finding of kidney cancer and non-Hodgkin lymphoma risks associated with diabetes is indecisive. Some experts reported that these cancers may have a link with type 1 diabetes.
Liver cancer and diabetes have some association as insulin released from pancreatic β-cells is transported through the portal vein and reaches the liver. Therefore, both pancreas and liver exposure to insulin is higher than other organs. The predominance of nonalcoholic fatty liver disease, steatosis, and cirrhosis is higher in diabetic patients. All these liver disorders increase the risk of liver cancer. Abnormal glucose metabolism is a characteristic sign of diabetes and that may consequently increase the risk of pancreatic cancer.
A metabolic disorder associated with cancer can cause a reduction of testosterone levels that leads to prostate cancer. Hyperinsulinemia and obesity are two other pathophysiological findings of diabetes that worsen the prostate cancer prognosis among male diabetic patients. Higher C-peptide levels are an indirect indication of insulin resistance that negatively impacts the survival rate in patients with prostate cancer and colorectal cancer. Epidemiological study findings also reported that diabetes may significantly increase mortality in cancer patients. Breast cancer risk is also higher among diabetic female patients than normal individuals.
Normal cells turn to neoplastic phenotype through multiple genetic hits that cause unwanted cell growth, invasion, and metastasis. These cellular changes lead to the transformation of normal cells to metastatic cells. Complex carcinogenesis involves multiple steps like initiation, promotion, and progression. Diabetes follows several pathological mechanisms like hyperinsulinemia, hyperglycemia, or chronic inflammation that may play role in the neoplastic process.
Glucose is one of the main culprits that potentially relevant mediator between diabetes and cancer. Cancer requires a higher supply of glucose to match the energy demand. Glycolysis generates ATP and increases oxidative stress. A high rate of glucose uptake is also detectable in cancer imaging testing. Experts believe that there is a possibility of untreated hyperglycemia influences neoplastic proliferation. Besides these, glucose uptake mechanisms involve in cancer can cause hyperglycemia. Hyperglycemic and hyperinsulinemia both are underlying conditions of diabetes that may activate tumor growth. The untreated condition of the tumor may turn to neoplastic growth.
