Lung cancer is one of the world’s most prevalent cancers. The most common cause of lung cancer is cigarette smoking. Lung cancer does not affect only smokers; it can also affect nonsmokers. A non-smoker is one who doesn’t smoke now but has smoked 100 or more cigarettes in their lifetime. Women are more likely at risk than men to develop lung cancer among non-smokers. The risk of death for non-smokers is low than smokers. Lung cancers in non-smokers are typically distinct from those that occur in smokers. 

Types of lung cancers in non-smokers 

Non-smokers are more likely to develop specific types of cancer including: 

Adenocarcinoma: Non-smokers have a higher risk of non-small cell lung cancer, especially adenocarcinoma. These are cancerous tumors that form in the outer areas of the lungs and can be present for years before symptoms appear. 

Squamous cell carcinomas: It’s a type of non-small cell lung cancer that affects people who don’t smoke, though it is much less prevalent than other types. 

Mesothelioma: It is caused by asbestos exposure, which causes tumors to form in the membrane that borders and protects the lungs, heart and abdominal cavity. 

Symptoms 

The majority of non-smokers show no early sign of lung cancer, which is typically not recognized until it has spread. However, some people do show symptoms early on like fatigue, minor shortness of breath, and upper back or chest pain. As the condition advances,  chronic cough, difficulty breathing and swallowing, bloody cough, wheezing, fever,  hoarseness, weight loss, and poor appetite will all be symptoms. 

Risk factors 

The major risk factors behind lung cancer in non-smokers include: 

Second-hand smoke: The inhalation of smoke from the burning of tobacco products is called second-hand smoke. Exposure to second-hand smoke causes 15-35% of lung cancer in non-smokers. 

Environmental exposures: Exposures of asbestos, chromium, and arsenic lead to lung cancer. Inhalation of indoor and outdoor air pollutants tends to cause lung cancer. Chronic exposure to cooking fumes from burning wood or frying has also been linked to an increased rate of lung cancer. 

Radon: Radon is a decay product of radioactive metals such as uranium-238 and radium-226.  It is known to be present in soil, rock, and groundwater and thus accumulate in homes. Exposure to radon within homes may lead to the development of lung cancer in non-smokers.  

Lung disease: Another important risk factor for the development of lung cancer in non-smokers is underlying lung disease, which can be due to many different factors which range from pre-existing disease or chemotherapy and radiation. 

Oncogenic viruses: Viruses such as Epstein-bar virus (EBV), Human papillomavirus (HPV),  and Hepatitis B and C are implicated in the development of cancer. 

Genetic factors: Lung cancer is believed to have a hereditary component in non-smokers since those with a family history of lung cancer are at a greater risk. Non-smokers may develop lung cancer as a result of genetic changes. These changes can be detected through gene testing  (molecular profiling). 

Treatment 

If adenocarcinoma is found early enough, surgery is the early phase of therapy. Chemotherapy may be given for eliminating any cancer cells that were not still present in the body after surgery. Because the majority of instances among non-smokers are caused by genetic alterations, targeted therapies that target these mutations have a high success rate in nonsmokers. Immunotherapy advancements, on the other hand, have had less of an impact on non-smoking lung cancer patients.  

Biomarker targeted therapy 

Lung cancers in non-smokers are usually caused by certain genes (biomarkers). Biomarker testing for newly diagnosed non-smoking lung cancer patients is critical for the development of targeted therapy. In recent years, advances in targeted therapy have improved non-smoker lung cancer survival rates. This enables doctors to develop a specific drug for a specific patient  based on the most detailed understanding of the patient’s gene alterations, known as “precision  medicine.” 

Precision medicine

Precision medicine or Personalised medicine refers to specific treatment based on the presence of specific biomarkers in a patient. 78% to 92% of lung cancers in non-smoking patients can be treated with precision drugs. Precision medicine target only specific genes in a patient’s tumor but not healthy cells. Non-smoker lung cancers can be effectively treated by precision medicine and have better outcomes, with fewer side effects than other types of treatment as it is designed to be more specific to cancer cells.