Lung cancer possesses a significant global health burden and is one of the most common cancers. Worldwide, every year around 2 million new cases, and approximately 1.76 million deaths occur due to Lung cancer. To raise awareness about risk factors, signs and symptoms, and the importance of early detection of lung cancer, every year, the entire month of November is observed as Lung cancer awareness month. 

Lung Cancer And Its Types

Lung cancer is a type of cancer that begins in the lungs and spreads to lymph nodes or other organs in the body, such as the brain. Based on the different microscopic appearances, lung cancer is of two types, namely small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). The NSCLC is the most common type and accounts for about 80 to 85% of lung cancer cases, while the SCLC accounts for 15 – 20% of cases. 

SCLC is also known as “oat-cell” cancer. It starts in the bronchi (centre of the chest) and metastasizes at a much higher rate. SCLC is divided into two subtypes, i.e. Small cell carcinoma (oat-cell cancer) and Combined small cell carcinoma. The primary risk factor of SCLC is cigarette smoking, and it is observed that the majority of the affected individuals smoke or have a history of smoking. As per DelveInsight’s analysis, total incident cases of SCLC in the 7MM (the United States, EU5 (the United Kingdom, Spain, France, Germany, and Italy) and Japan) was assessed to be 85,540 in 2017; also, it is being observed that there is a gender difference in disease. SCLC is found to occur more frequently in the male population as compared to females. About three-quarters of SCLC patients are diagnosed with extensive-stage SCLC, and if left untreated, it can be fatal within a few weeks. 

The NSCLC accounts for nine out of every 10 cases of lung cancer. According to the European Society for Medical Oncology (ESMO), in Europe,  NSCLC is the most common type of lung cancer, which accounts for 80─90% of all lung cancer cases. Similarly, as per the DelveInsight analysis, total incident cases of NSCLC in the 7MM were observed to be 484,726 in the year 2017. These cases are expected to grow during the study period 2017–2030.

Both types of cancer show different growth patterns and are treated differently. NSCLC tends to grow and metastasizes to other organs at a much slower rate as compared to SCLC. Similar to SCLC, NSCLCs is also closely associated with cigarette smoking; however, it can also be found in patients who have never smoked. In comparison to SCLC, it is relatively insensitive to chemotherapy and radiation therapy. According to the type of cells found in the tumour and the response to the treatment, the NSCLC is divided into three main types, which include Adenocarcinomas, Squamous cell carcinomas, and large cell carcinomas. 

What Are The Signs And Symptoms Of Lung Cancer?

At an early stage, it is difficult to notice the signs and symptoms of lung cancer. The primary reason being the symptoms are poorly understood at the early stages and often mistaken for other respiratory infection problems which share similar symptoms with lung cancer. The majority of the cases are diagnosed at the advanced stage when the symptoms become apparent. People with lung cancer have different symptoms; however, some of the most common symptoms include:

Pain in the chest area, back, or shoulders 

Coughing that gets worse with time or doesn’t go away

Loss of appetite 

Unexplained weight loss

Shortness of breath

Feeling tiredness

Apart from these, some other less common symptoms of lung cancer include difficulty swallowing or having pain while swallowing, wheezing, a hoarse voice, swelling in the face, and many others.

Risk Factors For Lung Cancer

The exact causes of lung cancer are unknown; however, it is closely linked to smoking (for both types of lung cancer). As per the CDC, in the United States, cigarette smoking is linked to about 80% to 90% of lung cancer deaths. Similarly, people who smoke cigarettes are 15 to 30 times more likely to get lung cancer or die from lung cancer than people who do not smoke. Young age smokers are at higher risk for lung cancer.  

Similarly, exposure to certain gases (such as asbestos, diesel exhaust, and radon) or air pollution can also significantly increase the chances of lung cancer. Radon, a naturally occurring radioactive gas, can cause lung cancer in non-smokers and smokers alike. As per the United States Environmental Protection Agency (EPA), radon is the second leading cause of lung cancer and is responsible for about 21,000 lung cancer deaths every year. About 2,900 of these deaths occur among people who have never smoked. Around one out of every 15 homes in the United States is thought to have high radon levels. Secondhand smoke is also one of the causes of lung cancer. Exposure to secondhand smoke can cause serious health problems in children and adults. CDC reported, in the United States, nearly one out of four people who don’t smoke, including 14 million children, were exposed to secondhand smoke during 2013–2014.

Some other factors such as age, personal and family history of cancer, poor diet, chronic inflammation from infections and other medical conditions, previous radiation therapy to the lungs are some of the risk factors for lung cancer.

Screening And Types Of Treatment Approaches For Lung Cancer

Screening for individuals who are at high risk for developing the disease can significantly improve the survival rates when the disease is at an earlier stage. The recommended screening test for lung cancer includes a low-dose computed tomography (also called a low-dose CT scan). The types of treatment methods for lung cancer differ according to the type of lung cancer and also on cancer’s stage. 

Different types of treatment are available for NSCLC. The recommended treatment option to a patient is considered based on several key factors, such as the age of the patient, previous medical history, health status, smoking history, and many others. Some of the standard treatment options for NSCLC include Surgery, Radiation therapy, Chemotherapy, Targeted therapy, Immunotherapy, Laser therapy, Photodynamic therapy (PDT), Cryosurgery, Electrocautery, and Watchful waiting.  Today, different emerging therapies are under development, which will provide efficient therapeutic approaches with a novel mechanism of action for the treatment of patients affected with NSCLC. Some of the key companies involving in developing therapies for the NSCLC at the global scale include AstraZeneca, Bristol-Myers-Squibb, AbbVie, Roche, Merk, Novartis, Pfizer, Takeda Pharmaceuticals, Eli Lilly, Johnson & Johnson, Sanofi, GlaxoSmithKline, and many others.

Similar to the NSCLC, there are several treatment options available for Small cell lung cancer (SCLC). The treatment pattern to follow is based on factors such as the stage of cancer, the patient’s health condition, the functioning of the lungs, and others. Surgery, chemotherapy, radiation therapy, and immunotherapy are approved as a treatment option for SCLC. Chemotherapy is the mainstay of the treatment for SCLC. Sometimes, more than one type of therapy is used. 

Due to nature & difficulty, and lack of treatment options in the market, as compared to NSCLC, there is a significant unmet need for patients suffering from SCLC. There are many areas of treatment in which pipeline products could improve upon existing therapies. Some of the pharmaceutical giants such as AstraZeneca, PharmaMar, EpicentRx, G1 Therapeutics, and several others are extensively involved in developing therapies to address the unmet needs of patients suffering from SCLC.

What Lies Ahead?

Lung cancer is one of the most highly diagnosed cancers, which result in a significant number of deaths worldwide every year. It severely affects the life expectancy and quality of life for the affected individual, along with it also causes a huge financial and mental burden on the affected families. Over the past few years, health bodies and governments have adopted several preventive and control initiatives to tackle the lung cancer problem. Similarly, pharmaceutical companies worldwide have also instigated drug development and clinical trial measures such as increasing use of biomarker testing, increase in the mutation-specific trials activity, and the development of cost-effectiveness therapies, which is expected to improve the quality of the care and health outcome for the lung cancer patients in the coming years.