Lung damaging activities associated with cancer
Lung cancer is a disease in which abnormal cells in the lungs proliferate uncontrollably, resulting in a tumor. The most common cancer in 2020 according to WHO was lung cancer which 2.21 million deaths after breast cancer which reported 2.26 million deaths.
The exact reason why lung cancer happens can be classically defined
as ‘multifactorial’. This can be environmental factors and then some
genetic factors as well. A slight increase of prevalence is noted
recently in young women, and cause of it remains an enigma. We as
Oncologist, regularly deal with cancer of the lung, head and neck and
even gastric, bladder etc., primarily caused by excessive tobacco
(smokeless/ smoked/ hooka/ second-hand smoke) intake. In most cases,
what begins as a fad turns into an obsession leading to the
life-threatening disease before the victim realizes it. Smoking is the
most critical risk factor for lung cancer development. Two-thirds of all
lung cancers are associated with smoking. But lung cancers in non-
smokers remain a unique separate entity(fewer than 100 cigarettes in a
lifetime). According to one data, 19% of all women lung cancers in US
were non-smokers.
Some other factors that lead to lung cancer include:
Radon, a radioactive gas found naturally in soil and rocks. Radon is a gaseous decay product of uranium-238 and radium-226 which damages lung epithelium by emitting alpha- particles. Aizawl distt, Mizoram has the highest concentration of indoor radon/ thoron and also the highest incidence of lung cancer in India.
Occupational Exposure: Commonly associated toxins include asbestos, chromium, and arsenic and Occupational exposure to organic dust (mining industry).
Arsenic has implicated as a cause of lung cancer where it contaminates drinking water. Whole-genome sequencing of the lung cancer of a never smoking patient with arsenic exposure revealed unusual tumor protein p53 (TP53) mutation.
Dietary factors: Higher intake of fruits and vegetables and low fat food may be protective against lung cancer (healthiest dietary pattern).
Indoor air pollutants such as vapors from cooking oil and the smoke from burning coal have been linked to lung cancer in women, particularly in Asia (India).
Outdoor air pollution is also associated with lung cancer risk. Using ambient fine particulate matter (PM2.5) as a measure of air pollution, there was a 15 to 27 percent increase in lung cancer mortality in never smokers.
Underlying lung disease and treatment- Idiopathic Pulmonary Fibrosis, previous exposure to radiation or chemotherapy.
Cancer Causing Viruses (oncogenic Viruses) like Human Papilloma Virus type 16 and 18. Also there is increased association with HIV infection.
Genetic factors: lung cancer was significantly more common among those with a positive family history, particularly of early-onset lung cancer (<50 years). Certain Chromosomal abnormalities have been identified and specific germline mutations have been identified in limited numbers of families with high rates of non-small cell lung cancer (NSCLC) in never smokers.
Estrogens — The role of estrogens and other female hormones in lung cancer risk in women is uncertain, regardless of smoking status. Studies show that the majority of NSCLCs express the estrogen receptor beta. Relationship of lung cancer incidence to early menopause, use of hormone therapy (like tamoxifen or HRT), age at first birth and number of children. However the results are not consistent.
Inflammation and other benign lung disease-The risk of lung cancer was elevated in patients with a history of emphysema, chronic bronchitis, pneumonia, and tuberculosis. The increased risk involve all histologic types of lung cancer (adenocarcinoma, squamous cell, small cell).
Genetic conditions like alpha-1 antitrypsin deficiency
Body mass index — there is an inverse relationship between body mass index (BMI) and lung cancer (especially small cell lung cancer),however it could be associated comorbidities or other factors.
Certain vitamin and beta carotene supplements have shown confounding results.
Opium use (illicit drug derived from the poppy plantis associated with an increased, dose-dependent risk of developing lung cancer .
Screening is a method of detecting cancer when there are no symptoms in a high-risk case: Low-dose helical CT scanning is the only early detection screening technique proven to reduce mortality in people at high risk of lung cancer. High risk individuals who require lung CT screening are long term smokers. Lung cancer screening by chest radiography and sputum cytology has not been shown to reduce lung cancer mortality rates.
Remember that ‘Cancer’ is importantly a “lifestyle disease”. Cancer may be curable if diagnosed early enough. Even if it isn't, the treatment should improve one’s quality of life and help you live longer. Also, we as oncologist want to convey to every individual to make their lifestyle choices wisely. Each person has a right to his/her life and health, and the decision about it solely lies upon themselves.
The article has been authored by Dr Niti Raizada, Director, Medical Oncology and Hemato Oncology, Fortis hospital Bannerghatta Road.