Written By: Longjam Dineshwori | Published : July 31, 2020 9:58 AM IST
Some studies have also reported higher incidence of some cancers in diabetic patients. © Shutterstock
Lung cancer is the most common cancer, responsible for nearly 1 in 5 cancer-related deaths worldwide- according to the World Health Organization (WHO). It is estimated that lung cancer kills more people every year than breast, colon, and prostate cancers combined. Since 2012, World Lung Cancer Day is observed every year on August 1 to raise awareness about this disease and its risk factors.
Smoking is considered to be the greatest risk factor for lung cancer, accounting for about 80 percent of all cases. However, it can also result from environmental factors and genetics. Environmental factors include exposure to radon, asbestos, arsenic, beryllium and uranium. There are also other lesser-known risk factors for lung cancer such as a history of cancer in another part of the body, age, family history, radiation to the chest area and lung diseases like chronic obstructive pulmonary disease (COPD). Some studies have also reported a higher incidence of some cancers, including colorectal, breast, endometrial, and pancreatic malignancies in diabetic patients than in the general population. This World Lung Cancer Day, let's explore the connection between lung cancer and diabetics.
A large U.K. retrospective study that appeared in Diabetes Care, a monthly peer-reviewed medical journal published by the American Diabetes Association, investigated the hypothesis that the rate of lung cancer is different in diabetic compared with non-diabetic patients.
Diabetic patients and non-diabetic control subjects were identified from the General Practice Research Database (GPRD), an observational database containing primary care records from throughout the U.K.
The researchers found no increased risk of lung cancer in diabetes patients. They assumed that the lower incidence may be partly due to shorter life expectancy in diabetes patients as lung cancer occurs more frequently in later life.
"The diabetic patients may be less likely to survive to have an effect of cigarette smoking on their lungs, particularly as smoking amplifies the excess coronary risk of type 2 diabetes," they wrote in their study paper.
Another study published online in the British Journal of Cancer in 2016 investigated the impact of pre-existing diabetes and diabetes treatments on lung cancer prognosis. The researchers followed 2484 women with confirmed incident lung cancer for an average of 2.9 years through the date of death or 29 August 2014.
The study results showed that compared with women with lung cancer but without diabetes, women with lung cancer and diabetes had significantly increased risk of overall mortality. Women with diabetes receiving insulin or metformin also had an increased risk of overall mortality.
"Our large prospective study provides evidence that pre-existing diabetes is associated with poor overall survival among women with lung cancer, but do not support the hypothesis that metformin use may have a protective effect in women with lung cancer and diabetes," the researchers concluded.
According to the researchers, diabetes may influence lung cancer progression and outcome by several mechanisms, including hyperinsulinemia, hyperglycaemia, or chronic inflammation, all of which may trigger cell proliferation and cancer progression. In addition, pre-existing diabetes may affect lung cancer outcome by influencing clinical decisions regarding lung cancer treatment or response to treatment, they noted.
