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Lung cancer in non-smokers: Understanding the different Cohort

After breast and prostate cancer, lung cancer is one of the most common types of cancer worldwide. Although the primary factor that is seen to cause lung cancer is smoking or the use of tobacco, did you know that several other factors can cause lung cancer?

Around 20,000-40,000 cases of lung cancer occur in individuals who do not smoke, which constitutes approximately 10-20% of the total cases of lung cancer reported each year. Non-smoker lung cancer is mainly observed in people who have smoked less than 100 cigarettes in their lifetime.

Exactly like every other cancer, lung cancer also starts from abnormal cells that grow rapidly at an abnormal rate. It can start at one area of the body and can metastasize (or spread) to the other organs or bones of the body.

Over time, there has been a decrease in the incidence of cancer among smokers due to the implementation of restrictions and public awareness campaigns regarding the dangers of smoking. However, a significant increase in cancer among non-smokers has been observed.

Who gets Non-smoker lung cancer the most?

In general, non-smokers account for 10-20% of male lung cancer patients and 50% of female lung cancer patients. Research has indicated that non-smoking women are more likely to be affected by lung cancer. Furthermore, a majority of female non-smokers with lung cancer (60-80% of cases) are reported from Asia.

The time to seek medical attention for non-smokers' lung cancer is around 3 months and is also diagnosed at a much later stage, such as 60% of such cancers are observed at Stage IV.

According to various research papers conducted on non-smoker lung cancer death rates, it is observed that females who are diagnosed have comparatively low mortality rates than males. And overall mortality rates of lung cancer in non-smokers are low compared to smokers' deaths.

How is a non-smoker’s cancer different from a smoker’s cancer?

It is noted that primary lung cancer is caused by two types of cancerous cells, Non-small cell lung cancer (NSCLC) and Small Cell lung cancer (SCLC). Cases that report smokers' lung cancer are mostly affected by the uncontrolled growth of small cell lung cancer, whereas non-smokers' cancer that was reported is mainly afflicted by Non-small cell lung cancer also called adenocarcinoma.

Non-smokers typically develop lung cancer that originates from the mucus-producing cells in the outer lining of small airways, called bronchioles. It has been observed that non-smokers' lung cancer tends to spread at a slower pace compared to that of smokers. Furthermore, the appearance of lung cancer in non-smokers is distinct from that of smokers. Smokers' cancer often appears as dark spots or lumps in the lungs, whereas non-smokers' cancer appears as an even layer of a black substance spread throughout the lungs.

Other Causes of lung cancer in Non-smokers

Unlike smoker's lung cancer, which is linked to known risk factors, non-smoker lung cancer is attributed to multiple factors that can easily be overlooked without an appropriate diagnosis.

Some of the most common reasons for non-smoker cancer are:-

Secondary smoking:- It is observed in people who have a smoker in the family, primarily a smoker spouse. In one of the research conducted on 55 subjects, it is observed that 27% of women who has a smoker spouse are prone to lung cancer.

Polluted environment:- Exposure to asbestos, chromium, and arsenic can cause the development of lung cancer in many patients. Other than this, countries that have less polluted air are seen to have a low rate of lung cancer than countries with high pollution rates.

Radon gas:- Radon gas is a naturally occurring substance that is invisible to the naked eye and found in outdoor environments. Thirteen research studies were conducted to examine the relationship between radon gas exposure and lung cancer, and the analysis revealed that approximately 15-20% of non-smokers' lung cancer cases are directly linked to exposure to radon gas.

Genetic factors:- Mutation in genes or inherited oncogenic genes can turn on or off tumor suppressor genes. People who have a history of lung cancer patients in their family are seen to be more prone to lung cancer development.


Some of the most common Symptoms of non-smoker Lung cancer are:-

1. Severe coughing that gets worse with time and blood coughing.

2. Chest pain and discomfort

3. Breathing trouble

4. Loss of appetite

5. Weight loss and trouble swallowing

6. Recurring lung infection

7. Constant fatigue

Early detection, diagnosis, and screening of lung cancer in Non-smokers

Early detection of non-smokers is rare as it doesn’t show much of symptoms in the early stage but if detected at the right time, non-smokers' lung cancer, can easily be removed with surgery.

For screening, a low-dose chest CT is considered appropriate in detecting non-smoker lung cancer. As for treatment, non-smoker lung cancer that is developed due to genetic mutation doesn’t respond to standard lung cancer treatment. So a specialized targeted treatment for the mutated cells.

Treatment of lung cancer in Non-smokers

After detecting the type of lung cancer, if it is not extremely genetic you can get regular treatments such as radiation therapy, chemotherapy, targeted therapy, and also a combination of all these treatments.

If metastatic NSCLC is detected, chemotherapy is the most effective treatment in that case. Chemotherapy along with targeted therapy is used in mutated cancer cells. Along with this in some cases, radiation therapy is also used after surgery that helps with targeting the area around which the cancer cells are noticed.

It is crucial to take into account the provision of supportive care such as pain management, nutritional support, and psychological support. The quality of treatment can be improved the quality of life and help by managing the symptoms and side effects of treatment

Overall, the treatment of non-smoker lung cancer is complex and requires a multidisciplinary approach, involving a team of medical professionals including oncologists, surgeons, radiation therapists, and other specialists.

Based on the information provided, it can be inferred that non-smoker lung cancer differs significantly from smoker lung cancer, not only in terms of its causes but also its treatment. Therefore, it can be considered a distinct category that requires a separate understanding.

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