Let the lungs breathe — defeat oncogenes.

7 min readAug 1, 2021

A simple guide for a lung cancer-free tomorrow.

The lungs of an individual are essential for survival. This pair of organs has a vital role in breathing where the oxygen needed by the body is taken in, and the waste carbon dioxide is filtered and exhaled out. To do this mechanism, the lungs have very sensitive tissues. One of the major growing global health problems is lung cancer (LC), and it is the leading cause of cancer deaths in men and the second leading cause of cancer deaths in women.

LC can be categorized into two main groups; primary LC and secondary LC. Primary LC is when cancer initiates in the lungs itself. This can be further classified into two other categories; non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). NSCLC is the most common out of the two giving rise to more than 87% of the cases. It can be developed in one of the three types of adenocarcinoma, squamous cell carcinoma or large cell carcinoma. SCLC is a rare type but spreads faster than NSCLC and is more common in heavy smokers.

Comprehensive reviews demonstrate that combustible tobacco is top listed as a causative risk factor for LC (around 80% — 90%) in both men and women. Nicotine is the addictive substance present in tobacco which is a natural alkaloid. It acts as an acetylcholine agonist by binding to nicotinic acetylcholine receptors present in the nervous system, releasing neurotransmitters such as dopamine, serotonin, norepinephrine, endorphins, and gamma-aminobutyric acid (GABA) into the bloodstream. Nicotine solely is not carcinogenic but increases tobacco dependency by upregulating nicotinic receptors causing genetic alterations.

Combustible tobacco is known to produce more than 60 carcinogens. Tobacco smoke is of two phases: the vapor phase and the particulate phase producing high amounts of free radicals per gram. The carcinogenesis mechanism of tobacco includes steps such as the abduction of carcinogens to DNA and their metabolites and damage through free radicals.

It is devastating to observe that young women are targeted explicitly in tobacco advertising, dominated by themes such as social desires and independence. Beliefs in weight loss through smoking motivates them to smoke. Unfortunately, even in the era of factual and scientifically proven risks to the fetus, an estimated percentage of 13%- 20% of women smoke during pregnancy.

Female smokers tend to develop adenocarcinoma of the lung than squamous cell carcinoma, which is mostly developed in men. Never-smokers with LC mainly develop adenocarcinoma and are also approximately 2.5 times more likely to be female than male. The bronchioloalveolar subtype of adenocarcinoma is more common among women with LC than among men.

It was observed by Bohadana et al, that the cessation rates of male smokers are 16% higher than that among female smokers, not solely affected by nicotine dependence but also behavioural factors suggesting that cessation programs could be improved by addressing the needs of women who wish to quit smoking rather than pharmaceutical intervention alone.

Cessation of smoking reduces the risk of lung cancer and shows improvement in those who have already been diagnosed. Smoking does not only cause LC. Prolonged smoking can manipulate cancer biology, making tumours resistant to cancer treatments, eventually leading to increased cancer-specific death.

Proven efficient and effective methods of reducing tobacco usage include prohibiting the youth for tobacco usage, taxation on tobacco products, anti-smoking campaigns and legislations and most importantly, evidence-based smoking cessation support pre and post-diagnosis of cancer. However, global tobacco control varies according to the respective governments, public awareness, tobacco industry and social patterns.

Research proves that side stream smoke is more of an environmental pollutant than the mainstream filtered smoke of cigarettes. People who passively inhale cigarette smoke are at more risk of exposure to carcinogens than actual smokers. Non-smoking spouses of smokers have a risk of around 20–30% to develop LC eventually. Therefore, it can be said that there is no safe level of exposure to side stream cigarette smoke.

Cancer is usually common with older age as their DNA tends to damage and shorten their telomeres biologically. It is usually diagnosed with a median age of around 70 for both men and women. LC is also observed in young adults. Most of them diagnosed with non-small cell lung cancer tend to be females with a history of adenocarcinoma and no smoking history where genetic factors play a significant role.

There’s a conflictive possibility that women are more susceptible to LC than men, whereas a higher incidence in non-smoking women than in non-smoking men. Hormonal influence also plays a role in the development of LC in women, where oestrogen receptors were observed to be overexpressed in the lung adenocarcinoma in women but are not present in normal lung tissue. It was also observed that estradiol promotes the growth of adenocarcinoma cells in vitro in women but not in men. Anti-tumour effects were observed in vitro with the use of anti-oestrogen compounds.

In the category of occupational exposure, asbestos is a highly active carcinogen. It is a silicate mineral commonly used in construction. Exposure to asbestos increases the risk of LC fivefold, whereas smoking and exposure to asbestos develop a synergistic effect on the lungs to increase the possibility of developing LC. Exposing the body to various types of radiation or getting radiation therapy also increases the risk of developing cancer.

Infection and inflammation in the lungs, such as tuberculosis, also can cause carcinogenesis, irrespective of the smoking status. Also, patients with HIV were observed to have prevalent deaths related to LC. The immunosuppression in their bodies can be the justification for this consequence. An individual having a family history of LC involvement has a 1.7% increase of risk for the development of LC. LC in never smokers is mainly associated with adenocarcinomas with the involvement of genetic mutations such as EGFR mutation, which comes in handy for targeted therapy.

LC usually does not show any symptoms until later stages. These symptoms include shortness of breath, which the blockage of airways may cause due to a growing tumour, coughing up blood due to airways damage-causing airways to bleed, prolonged cough, bone pain, headaches, and headaches lethargy. Early diagnosis of LC through screening is proven to reduce mortality, whereas cessation of smoking for seven consecutive years showed higher survival benefits to the patient. However, a lack of resources for cessation support has become a primary barrier. LC has a very low 5-year relative survival rate of around 18% for all stages combined. However, advanced lung cancer has an even lower prognosis 5-year relative survival rate of around 5%.

Diagnosis of LC can be made in multiple methods. The X-ray image of the lungs reveals abnormal structural changes. However, a CT scan is needed to detect small tumours. Sputum cytology techniques are another way of detecting LC under the microscope. Cancer cells present in sputum can be detected through microscopy.

The scariest complication of any common cancer is that it can metastasize and spread to other parts or organs of the body. Once LC is spread beyond the lungs, there is a very low chance of cure or survival.

If diagnosed early, cancerous cells will be confined to a small region and will be eliminated through surgery. But this is not suitable for patients of older age or if the person has general health issues such as immunosuppression, where radiotherapy can be an alternative treatment method. If cancer has metastasized or has grown to a larger area of the organ, neither surgery nor radiotherapy can be used. The process of chemotherapy is the mode of treatment at that stage. Novel medicine is also more involved in developing cancer-specific targeted therapies. These therapeutics still cannot be used as a cure, but it is very efficient in slowing down the growth and spread of cancer.

Therefore, it is very important to take all measures possible to prevent the increase of this deadly disease, where it is very close to reaching epidemic levels in many countries caused mainly by their social habits and work exposures. Preventive measures include educating younger generations on what this cigarette smoke does to the human body, rather than letting them believe tobacco advertisements that try to prove that smoking is socially acceptable. Cessation campaigns will help a significant population of the smoking community as many people tend to smoke as a stress relief mechanism. Following proper safety procedures at workplaces with exposure to carcinogens will also help reduce the risk of developing LC. Moreover, a generally healthy lifestyle is essential to maintain a healthy body. As we commemorate world lung cancer day on the 1st of August, it is important that we remember all who suffer from this deadly complication and all those who were unable to fight this cancer away. It is also important that we take possible measures to increase public awareness and initiate measures to reduce tobacco usage and other carcinogens causing LC. LC grows and will keep on growing unless we fight together to defeat it.

Written by: Rasanie Goonewardena

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Let the lungs breathe — defeat oncogenes.

Written by YGSL

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