Amidst the myriad of medical challenges that humankind faces, lung cancer is a mysterious adversary, impacting the lives of millions worldwide. Lung cancer casts a substantial shadow on global health, accounting for approximately 11.4% of all cancer cases. Shockingly, in 2020 alone, there were an estimated 2.2 million new lung cancer cases diagnosed worldwide, and this devastating disease claims about 1.8 million lives every year. In India, the burden of lung cancer is rapidly increasing, with over 1.5 million cases reported annually. Constituting nearly 6.9% of all cancer cases in the country, lung cancer poses a significant challenge to public health. Tragically, the majority of cases in India are detected at advanced stages, contributing to the persistently high mortality rate.
World Lung Cancer Day, commemorated annually on August 1st since 2012, serves as a powerful reminder to join hands and take a stand against lung cancer worldwide. This significant day is not just about raising awareness; it's about fostering a united front to combat the prevalence of this formidable disease. Together, we can educate and advocate for lung health, supporting those affected by the illness and promoting preventive measures.
Causes of Lung Cancer
Lung cancer is a multifaceted challenge for Indians, arising from a combination of lifestyle choices, environmental factors, and even genetic predisposition. Smoking stands tall as the leading cause, with tobacco use, including cigarettes, bidis, and hookahs, directly linked to a significant proportion of lung cancer cases. Even non-smokers face risks through secondhand smoke exposure, particularly children and non-smoking adults living or working in smoking environments. Furthermore, the alarming levels of air pollution in India play a major role in the increasing incidence of lung cancer, with pollutants like PM, NO2, SO2, and VOCs damaging respiratory systems and fueling cancer development. Research published in the Journal of Cancer Epidemiology reinforces this link between long-term exposure to air pollution and elevated lung cancer risk in urban areas of India.
Occupational hazards also contribute, with workers in construction, mining, and manufacturing industries at risk due to contact with carcinogenic substances like asbestos. Employees in the transportation sector, especially those exposed to diesel engine exhaust fumes, also face heightened risks. Radon, a radioactive gas seeping into buildings, and indoor air pollution from poorly ventilated spaces with solid fuel usage are further factors exacerbating the risk of lung cancer.
Genetics also play a role, with some individuals genetically predisposed to developing lung cancer, often indicated by a family history of the disease. The most well-known genetic predispositions associated with lung cancer are mutations in genes such as EGFR (Epidermal Growth Factor Receptor) and ALK (Anaplastic Lymphoma Kinase). These mutations are more commonly found in certain types of non-small cell lung cancer (NSCLC) and are associated with a better response to targeted therapies. Other genetic factors that have been linked to lung cancer risk include variations in the TP53 gene, which is involved in cell cycle regulation and DNA repair, as well as variations in genes related to detoxification pathways for environmental carcinogens.
The impact of our food choices on inflammation, oxidative stress, and DNA repair mechanisms is believed to be linked to an increased risk of lung cancer. For instance, diets high in saturated and trans fats, commonly found in processed and fried foods, have been found to promote inflammation and contribute to oxidative stress, potentially damaging cells and raising the likelihood of cancer. Similarly, regular consumption of red and processed meats, like beef, pork, and bacon, has been linked to a higher risk of lung cancer due to compounds generated during high-temperature cooking that may be harmful. On the other hand, diets lacking in fruits and vegetables, rich in antioxidants and protective nutrients, have also been linked to an increased risk. These nutrients are instrumental in neutralizing harmful free radicals and supporting the body's defence against cancer development. Moreover, consuming foods with a high glycemic index, such as sugary snacks and refined carbohydrates, could contribute to an increased risk as they lead to rapid spikes in blood sugar levels, promoting inflammation and cell damage. Lastly, diets low in dietary fibre, often found in whole grains, legumes, fruits, and vegetables, have also been associated with a higher risk. Fibre supports gut health and may help in reducing inflammation and oxidative stress.
Types of Lung Cancers
Lung cancer manifests in two primary types: Non-Small Cell Lung Cancer (NSCLC) and Small Cell Lung Cancer (SCLC).NSCLC encompasses several subtypes, each presenting unique characteristics and implications for treatment. The major ones are mentioned herein:
a) Adenocarcinoma is the most common subtype of NSCLC, accounting for approximately 40% of all lung cancer cases. Often found in the outer regions of the lungs, adenocarcinoma is commonly associated with genetic mutations, such as Epidermal Growth Factor Receptor (EGFR) and Anaplastic Lymphoma Kinase (ALK) mutations.
b) Squamous Cell Carcinoma is found in the central airways of the lungs. Approximately 25% of NSCLC cases are of this type. Squamous cell carcinoma is closely linked to a history of smoking, and its diagnosis may impact treatment decisions.
c) Large Cell Carcinoma accounts for about 10-15% of NSCLC cases. It is a less common subtype and can appear in any part of the lungs.
On the other hand, SCLC is a highly aggressive form of lung cancer, accounting for about 15% of all lung cancer cases. SCLC is strongly associated with heavy smoking, and its rapid growth and tendency to spread make it challenging to treat.
Common Symptoms and Awareness
Lung cancer, often known as the "silent disease," can present in a variety of ways. Common symptoms include a persistent cough that lingers for several weeks or worsens over time, unexplained weight loss, and a persistent feeling of fatigue or weakness without any apparent reason. Some may experience chest pain or discomfort, difficulty breathing, or notice blood in their sputum. Paying attention to any changes in respiratory health and seeking medical attention immediately is vital. Regular health check-ups are crucial for those at higher risk, such as smokers or individuals with a family history of lung cancer.
An early referral to a Pulmonologist can be truly transformative. These Chest Physicians possess specialized expertise in recognizing and interpreting lung-related symptoms, enabling them to conduct comprehensive evaluations for lung cancer diagnosis. Utilizing cutting-edge diagnostic tests like bronchoscopy, endobronchial ultrasound, and thoracoscopy, pulmonologists can confirm the presence of cancerous cells and determine the most suitable course of action. Their proficiency in understanding the intricacies of lung health is instrumental in promoting early detection and improving patient outcomes in the battle against lung cancer. Trusting in the expertise of pulmonologists can pave the way for better chances of survival and a brighter future for those affected by this challenging disease.
Lung Cancer Diagnosis
Diagnosing lung cancer involves a series of tests that help doctors understand what's happening inside the lungs. These tests are like puzzle pieces, and when put together, they create a clearer picture.
Sputum examination is the simplest, non-invasive test wherein a sputum sample is examined under a microscope for any abnormal cells or cancerous markers. Although it may not always directly pinpoint the presence of lung cancer, sputum examination can indicate the need for further investigations, such as imaging or biopsies.
Radiological techniques have revolutionized the diagnosis and staging of lung cancer, enabling early detection and personalized treatment strategies. A chest X-ray acts as an initial screening, capturing images of the lungs to detect any unusual findings. Moving forward, CT scans offer more detailed insights, revealing the size, location, and potential spread of tumours with remarkable precision. PET-CT, a powerful combination of positron emission tomography and CT, further aids in the detection of cancerous activity throughout the body. Recent advancements also include MRI and liquid biopsy techniques, adding to the arsenal of diagnostic tools.
Pulmonologist's role is crucial in diagnosing lung cancer, and the key procedures they utilize are bronchoscopy, endobronchial ultrasound (EBUS), and Medical thoracoscopy. These procedures help pulmonologists obtain tissue samples from the lungs, lymph nodes, or pleura for accurate diagnosis, staging, and treatment planning. They are all minimally invasive procedures and are usually done as a daycare procedure and the patient may be discharged the same day or in the case of thoracoscopy within a day or two. These methods allow the Pulmonologist to achieve more accurate and targeted diagnoses by directly visualizing and sampling suspicious areas and perhaps avoid unnecessary surgery.
Bronchoscopy is a procedure where a thin, flexible tube called a bronchoscope is inserted through the nose or mouth and into the airways under local anaesthesia. The bronchoscope has a tiny camera and a light source, allowing the pulmonologist to visualize the trachea, bronchi, and smaller airways. This enables the identification of any abnormalities, such as tumours, inflammation, or infections. During a bronchoscopy, the pulmonologist can directly visualize suspicious areas and take biopsy samples. These tissue samples are sent to a pathologist for examination under a microscope.
Endobronchial Ultrasound (EBUS) is an advanced bronchoscopic technique that allows pulmonologists to perform real-time ultrasound imaging of the airway walls and structures adjacent to the airways, such as the lymph nodes in the mediastinum (the area between the lungs).EBUS is particularly useful for diagnosing lung cancer that has spread to nearby lymph nodes. During the procedure, a specialized bronchoscope with an ultrasound probe attached to its tip is inserted through the airways. The pulmonologist can visualize and measure the lymph nodes, and with the guidance of EBUS, they can obtain biopsy samples from these nodes for evaluation.
Medical Thoracoscopy, also known as Pleuroscopy, is a simple keyhole procedure. During thoracoscopy, a small incision is made in the chest wall, and a thin, flexible tube with a camera (thoracoscope) is inserted into the chest cavity. Medical thoracoscopy allows the pulmonologist to visualize the space between the lungs and the chest wall (pleural cavity). By directly examining the lung tissue and pleura, the pulmonologist can obtain biopsy samples and pleural fluid for examination. These samples provide valuable information about the presence and type of lung cancer, as well as its stage and spread.
Lung cancer staging
Lung cancer staging is like creating a roadmap that helps doctors understand how far the cancer has spread within the lungs and to other parts of the body. It's a way to classify the cancer based on its size and location, and whether it has spread beyond the lungs. Staging helps doctors determine the best treatment plan and predict the outlook for the patient. The staging process typically involves different tests, like imaging scans and sometimes biopsies, to gather information about the tumour. The stages are usually labelled from 0 to 4, with stage 0 being the earliest and stage 4 being the most advanced, indicating that the cancer has spread to other organs. Understanding the stage of lung cancer is essential because it guides doctors in deciding which treatment options are most suitable. Early-stage cancers may be treated with surgery or radiation, while more advanced cancers may require a combination of treatments like chemotherapy, targeted therapy, or immunotherapy. Staging also provides valuable information to the patient and their family, as it gives an idea of the cancer's severity and what to expect during treatment. While a lung cancer diagnosis can be overwhelming, knowing the stage can help patients and doctors make informed decisions to fight the disease effectively.
Treatment Options for Lung Cancer
1. Surgery is the primary treatment for early-stage non-small cell lung cancer (NSCLC). It involves removing the tumour along with the surrounding tissue. In select cases, minimally invasive techniques like video-assisted thoracoscopic surgery (VATS) may be utilized for the procedure.
2. Radiation Therapy is employed to target and destroy cancer cells using high-energy rays. It can be administered as a standalone treatment or in combination with surgery or chemotherapy. Stereotactic body radiation therapy (SBRT) is an advanced technique that delivers precise radiation doses to the tumour, sparing healthy tissues.
3. Chemotherapy is a powerful treatment for lung cancer that works throughout the entire body to target and control cancer cells. The good news is that many chemotherapy drugs can now be taken orally, which means patients can administer them at home, reducing the emotional and mental stress of frequent hospital visits and potentially shortening hospital stays.
4. Immunotherapy is an advanced lung cancer treatment that supports the body's immune system in fighting cancer cells. It has demonstrated promising outcomes, particularly for certain types of lung cancer that have not responded well to other treatments. Patient selection for this therapy considers factors such as the type and stage of lung cancer, as well as the individual's overall health. Examples include PDL1 inhibitors like Pembrolizumab, atezolizumab, Durvalumab, and Nivolumab.
5. Targeted therapy focuses on specific genetic or molecular changes in cancer cells. It works by blocking proteins or molecules involved in cancer growth. Examples include drugs like Erlotinib, Gefitinib, and Osimertinib, which target the EGFR mutation, and Crizotinib, Ceritinib, and Alectinib, which target the ALK gene rearrangement. Crizotinib is also effective against tumours with ROS1 gene rearrangement.
6. Palliative therapy in lung cancer aims to improve patients' quality of life and manage symptoms. It includes pain relief, symptom management (such as shortness of breath), supportive care (physical and emotional support), nutritional support, and oxygen therapy if needed. Additionally, it may involve pleural interventions for fluid buildup and counselling for patients and their families. Palliative care helps patients cope with the challenges of lung cancer and maintain dignity throughout their journey
Prevention Strategies
Preventing lung cancer is within our grasp, and adopting a few key lifestyle changes can significantly reduce our risk. First and foremost, quitting smoking or avoiding exposure to secondhand smoke is the single most crucial step we can take. Smoking is the leading cause of lung cancer, and quitting at any age can make a remarkable difference in our lung health. A diet rich in fruits, vegetables, and whole grains provides essential antioxidants and nutrients that support our body's defence against cancer. Regular exercise not only improves our cardiovascular health but also enhances lung function and reduces the risk of lung cancer. Moreover, being cautious about occupational hazards and indoor pollutants, such as asbestos and radon, can further safeguard our lung health. Ensuring proper ventilation and wearing protective gear in high-risk workplaces are essential preventative measures. Equally vital is being aware of any concerning symptoms, such as a persistent cough, difficulty breathing, or unexplained weight loss, and seeking medical attention promptly.
Even though medicine has advanced leaps and bounds in recent years, early detection is key to the successful management of lung malignancies. Therefore paying attention to our bodies and promptly addressing any unusual changes is paramount.
(Dr Padmavathy R is Senior Consultant-Pulmonologist, Meitra Hospital, Calicut)
