Dr. Shyam P Lohani

Lung cancer occurs when cells divide in the lungs uncontrollably, causing tumours to grow in size. The tumours hamper the breathing ability and also spread to lymph nodes and other parts of the body.

Nearly 10 million deaths were attributed to cancer in 2020, making it a leading cause of death worldwide. It accounts for one in six deaths (WHO, 2022). The most common cancers found among people are breast, lung, colon, rectum, and prostate cancers. However, the most common cause of cancer deaths in 2020 was lung cancer which accounts for 1.80 million deaths. In Nepal too, lung cancer is the most common cause of cancer deaths. Nearly 15,000 deaths are due to lung cancer in Nepal with a 16 per cent incidence.

Prostate & breast cancer
Lung cancer is the second most common cancer seen among both men and women. In men, prostate cancer is more common, while in women breast cancer is found to be the most common. Lung cancer mainly occurs in older people. Most people diagnosed with lung cancer are 65 or older. However, a very small number of people diagnosed are younger than 45 years of age. The average age of people at the time of diagnosis is about 70. Almost 25 per cent of all cancer deaths are attributed to lung cancer among both men and women. About one in 15 men develops lung cancer in their lifetime and the risk is about one in 17 among women. Both smokers and non-smokers develop lung cancer. For smokers, the risk is much higher as compared to those who do not smoke.

Lung cancers are typically divided into two major types based on the appearance of lung cancer cells under the microscope. The two general types of lung cancer include small cell lung cancer and non-small cell lung cancer. Small cell lung cancer occurs almost exclusively among heavy smokers. Squamous cell carcinoma, adenocarcinoma, and large cell carcinoma are examples of non-small cell lung cancers.

Lung cancer typically does not show signs and symptoms in its earliest stages but typically occur when the disease is in its advanced stages. Signs and symptoms of lung cancer may include a new cough that is persistent, blood in cough, shortness of breath, chest pain, hoarseness, weight loss, bone pain, and headache.
Smoking is responsible for the majority of lung cancers both among smokers and in people exposed to secondhand smoke. Moreover, lung cancer also occurs among people who never smoked and in those who were never exposed to secondhand smoke. In such cases, there is no clear cause of lung cancer.

Smoking causes damage to the lining of cells in the lungs. Cancer-causing substances in cigarette smoke make changes in the lung tissue. At first, our body may be able to repair the damage but with each repeated exposure, normal cells that line our lungs are increasingly damaged. Over time, repeated insult causes cells to behave abnormally, and ultimately, cancer may develop.

There are several risk factors for lung cancer. Some risk factors can be controlled and modified; however, other factors such as family history cannot be controlled. The major risk factor for lung cancer is smoking. The risk of lung cancer increases with the number of cigarettes smoked each day and the number of years of smoking. Smoking cessation at any age can significantly lower the risk of developing lung cancer.

The risk of lung cancer also increases with exposure to secondhand smoke. Radiation therapy to the chest for another type of cancer increases the risk of developing lung cancer. Similarly, radon gas, exposure to asbestos, and other carcinogens such as arsenic, chromium, and nickel can increase the risk of developing lung cancer. People with a familial history of lung cancer have an increased risk of the disease.

Awareness
Once the diagnosis of lung cancer is made, the survival depends on the stage of cancer. A combination of chemotherapy, radiotherapy, immunotherapy, and surgery is utilised for the treatment of lung cancer. Palliative care is recommended for those with advanced stages of lung cancer. The lung cancer five-year survival rate (18.6 per cent) is much lower than many other leading cancers, such as prostate (98.2 per cent), breast (89.6 percent), and colorectal (64.5 per cent). However, the five-year survival rate for lung cancer is 56 per cent for cases detected when the disease is still localised within the lungs (American Lung Association, 2020).

The best approach to prevent lung cancer is not to smoke and quit smoking for smokers. It is advised to avoid secondhand smoke. Take precautions to protect yourself from exposure to toxic chemicals at work with appropriate protective equipment. There have been several studies that have looked at the link between lung cancer and diet. Although there are no definite conclusions, there are benefits for people who maintain a healthy weight, exercise regularly, have a low intake of saturated fat, and do not drink alcohol.

A diet comprised of fruits and vegetables has been shown to decrease the development of lung cancer; therefore a healthy diet with a variety of fruits and vegetables is advised. A moderate level of physical activity is said to have a preventive effect, thus it is suggested to exercise most days of the week. Those who do not exercise regularly should start out slowly and extend it to most days of the week. It is urged to all concerned health authorities to expand the regular lung cancer screening throughout the country. The comprehensive awareness programme on lung cancer is also important to detect lung cancer early, improve the outcome and increase survival.

(Dr. Lohani is the clinical director at the Nepal Drug and Poison Information Centre. lohanis@gmail.com)