Lung cancer

Lung cancer is the most common cause of cancer-related death worldwide. In 2012, there were 1.8 million new cases globally. The mortality rate for this cancer is high, with a 5-year survival rate after diagnosis in the United States being only 18%.

A unique aspect of lung cancer is its strong association with a potentially preventable risk factor: smoking. Smoking any form of tobacco, including cigarettes, cigars, and hookahs, has significant health consequences.

However, half of all lung cancer patients are nonsmokers, which is attributed to the complex and multifactorial nature of its types.

Lung cancer is broadly divided into two subtypes: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). Tobacco use is the cause of 97% of small cell lung cancers, the subtype most strongly linked to smoking and hookah use. The prevalence of SCLC mirrors the prevalence of cigarette and hookah use in a society, with a lag of about 20 years. For instance, in America, lung cancer accounted for less than half a percent of all cancers until the 20th century because smoking was not yet widespread. Cigarette use peaked in the 1960s (before its harmful effects were widely known), and the peak incidence of SCLC followed in 1984. Historically, cigarette use was much higher among men than women, so lung cancer prevalence followed this pattern. Today, that gender gap has largely disappeared. Studies have shown that different cancer rates between genders in societies simply reflect smoking patterns and are not due to inherent biological or genomic differences between men and women.

Cigarette smoke contains over 50 different carcinogens. The presence of a filter does not eliminate this risk; some research even suggests filters may increase inhalation intensity, potentially introducing more carcinogens into the body.

Genetics also play a role in developing lung cancer, especially in non-smoking-related cases. Having a first-degree relative with lung cancer, particularly if they were diagnosed before age 60, increases the risk. Human genome studies have identified specific genetic variations that predispose individuals to the disease.

Occupational Exposures

Approximately 10% of lung cancer cases are related to occupational exposures. Contributing factors include exposure to arsenic, asbestos, beryllium, chromium, nickel, and fossil fuels. If concerned about workplace risks, you can consult an occupational physician and use personal protective equipment (PPE) to mitigate them. Excessive exposure to X-rays and the presence of certain chronic diseases, such as chronic obstructive pulmonary disease (COPD), are also predisposing factors. Extensive studies have shown an inverse relationship between lung cancer incidence and the amount of fruits and vegetables consumed.

Prevention

The most powerful prevention tool is smoking cessation. Quitting smoking, even in your seventies, is effective and it is never too late! Successfully quitting requires a plan, often involving nicotine replacement therapy (NRT) or other medications, and consultation with a doctor or a certified counselor—it’s not just a matter of willpower. With a structured approach, the success rate is high.

Even for patients diagnosed with lung cancer, the notion that “it’s too late to quit” is incorrect. Quitting smoking improves treatment response, increases quality of life, reduces the risk of developing a second primary cancer (common in smokers), and, most importantly, continuing to smoke doubles the mortality rate for the affected patient!

Studies on using various vitamins to reduce lung cancer risk have not been successful.

Screening

Unlike cancers such as breast, cervical, or prostate cancer, lung cancer lacks a slow-progressing, pre-cancerous or easily curable early stage. Therefore, screening the general population is not beneficial. However, some guidelines recommend periodic low-dose CT scans for individuals with a very high smoking history (calculated as pack-years ≥ 30, e.g., 1 pack/day for 30 years) to detect the disease at an earlier, more treatable stage.

Symptoms

The disease is often asymptomatic in its early stages. As it progresses, it can lead to cough, weakness and lethargy, coughing up bloody sputum (hemoptysis), and shortness of breath. Patients may experience just one or a combination of these symptoms. A relatively common syndrome called “Superior Vena Cava (SVC) Syndrome” may also occur, presenting with facial and neck swelling, plethora (redness), and shortness of breath due to obstruction of the superior vena cava. If the disease metastasizes to other organs like the brain, bones, or liver, symptoms related to those sites will appear.

Diagnosis

Diagnostic methods vary depending on the presentation and extent of the disease. They generally include CT scans, PET scans, mediastinoscopy (visualization and biopsy inside the chest using a scope), and surgical biopsy.

Prognosis

The prognosis and response to treatment depend on the disease stage, tumor type, genetics, environmental factors (such as continued smoking and malnutrition), and particularly underlying comorbidities that weaken the body and limit the ability to administer full-dose therapy.

A patient’s prognosis is not static and can improve or worsen during the course of the illness based on the factors mentioned above.

Treatment

Treatment is complex and based on the disease stage (I to IV), the patient’s underlying condition, and the molecular and laboratory characteristics of the tumor.

Treatment modalities include surgery, chemotherapy, radiation therapy, and immunotherapy (drugs that activate the body’s immune system against cancer). One or a combination of these methods is used based on the aforementioned conditions.

Given the use of various methods, lung cancer treatment is multidisciplinary, requiring collaboration between specialists in surgery and oncology (cancer medicine).

Source

Devita, Hellman, and Rosenberg’s CANCER: Principles & Practice of Oncology

If you suspect you have lung cancer, after consulting with your family/general physician (who will rule out other more common possibilities), you can be referred to one of the following specialists:

• Thoracic Surgeon
• Radiation Oncologist
• Pulmonologist (Respiratory Medicine Specialist) or Hematologist-Oncologist

The management of lung cancer involves overlap between these specialties, and the treating specialist will utilize multidisciplinary team (MDT) meetings to seek input from others as needed.