Lung

What is lung cancer

Among all neoplasms, lung cancer is the most incident type (with new cases) and causes the highest number of deaths worldwide. In Brazil, it is the second most common in both men and women (behind only non-melanoma skin cancer). According to data from the Global Cancer Observatory (GLOBOCAN), in 2020, 11.4% of all new cancer cases globally were lung cancer.

INCA estimates that in 2020, 30,200 new cases were diagnosed in Brazil, with 17,760 in men and 12,440 in women. The disease was responsible for 26,498 deaths in the country in 2015.

The good news is that lung cancer can have a lower incidence by controlling its main risk factor, smoking. In fact, its incidence rate has been decreasing since the 1980s among males and since the 2000s among females. This occurred due to awareness campaigns about the harms of smoking and passive tobacco exposure. Approximately 85% of diagnosed cases are associated with tobacco product consumption.

Subtypes of lung cancer

There are two main types of lung cancer, which are:

1. Non-small cell lung cancer (NSCLC) – 80% to 85% of lung cancers are NSCLC. The main subtypes of NSCLC are:

• Adenocarcinoma – it is the most predominant type currently. It begins in the cells that secrete substances such as mucus. This type of lung cancer mainly occurs in smokers or former smokers, but it is also the most common type of lung cancer seen in non-smokers. It is more common in women than in men and is more likely to occur in young people than other types of lung cancer;

• Squamous cell carcinoma (or epidermoid) – it begins in squamous cells, which are flat cells that line the inside of the airways. It is usually related to smoking and tends to be located in the central part of the lungs, near the bronchus, which is the main airway of the human body; and
• Large cell carcinoma (undifferentiated) – it can arise anywhere in the lung. It tends to grow and spread quickly, making it difficult to treat.

1. Small Cell Lung Cancer (SCLC) – 10% to 15% of all lung cancers are SCLC, which tends to grow and spread more quickly than NSCLC. The rapid growth of its cells makes it more sensitive to treatment with chemotherapy and radiation therapy, and its aggressiveness is associated with higher rates of disease recurrence (return). Additionally, about 70% of people with SCLC already have metastases at the time of diagnosis.

Symptoms and signs of lung cancer

While they can arise early in the disease’s development, symptoms of lung cancer typically do not occur until an advanced stage is reached. They are not specific to the disease, and the most common ones are:

• Persistent cough;
• Coughing up blood;
• Chest pain;
• Bone pain;
• Headache;
• Hoarseness;
• Shortness of breath or worsening of it;
• Weight loss and loss of appetite;
• Recurrent pneumonia or bronchitis;
• Pleural effusion (abnormal accumulation of fluid in the pleural cavity);
• Feeling tired or weak;
• Change in the usual cough pattern in smokers, where episodes occur at unusual times.

1. Other less common tumors that can occur in the lungs or bronchi include neuroendocrine tumors (carcinoids), adenoid cystic carcinomas, and mucoepidermoid carcinomas, among others.

Diagnosis of lung cancer

Individuals at increased risk for lung cancer should consider undergoing annual preventive screening. According to the US Preventive Services Task Force, it is suggested that annual screening with low-dose chest computed tomography (CT) be performed for adults aged 50 to 80 years who are at high risk for lung cancer (have smoked at least 20 pack-years and are current smokers or former smokers who quit smoking within the last 15 years).

For patients suspected of having lung cancer, the doctor may request some of the following tests:

• Chest X-ray – the most common imaging test for an initial attempt at diagnosis (when symptoms are present) or through which lung tumors are detected incidentally (when requested for other health reasons of the patient). The X-ray allows clear visualization of the lungs, where tumors or suspicious images that lead to further investigation through other exams can be seen.

• Biopsy – it is used to collect a small sample of cells that will be analyzed later (to determine if they are cancerous or not). Lung biopsy can be performed in several ways:

• Bronchoscopy – the doctor examines the lung airways using an illuminated tube that descends through the throat and reaches the lungs;

• Mediastinoscopy – an incision is made at the base of the neck, behind the sternum, through which surgical instruments are inserted to collect tissue samples from the lymph nodes. The process is painless, as it is done under anesthesia;

• Image-guided needle biopsy – the doctor uses imaging techniques, such as X-rays or CT scans, to guide a needle through the chest wall and collect samples of lung tissue.

If cancer is indeed diagnosed, the doctor will request further tests to determine the stage at which it is, which will be useful in choosing the treatment.

The stages of lung cancer are indicated by Roman numerals ranging from I to IV, with lower stages indicating that the cancer is limited to the lung and stage IV indicating advanced cancer that has spread to other areas of the body.

h6-Treatment of lung cancer

The treatment of lung cancer is multidisciplinary, meaning it requires a team of professionals from different specialties, such as an oncologist, thoracic surgeon, pulmonologist, radiation oncologist, interventional radiologist, nuclear medicine physician, nurse, physiotherapist, psychologist, nutritionist, and social worker.

In patients with localized disease and no enlarged lymph nodes (lymphadenopathy) in the mediastinum (the region between the two lungs), the treatment is usually surgical, with or without adjuvant chemotherapy and/or radiotherapy.

For those with localized disease in the lung and lymph nodes, treatment may involve concurrent radiotherapy and chemotherapy, followed by immunotherapy in those who did not experience disease progression (meaning the cancer did not increase in size or spread to another location). In selected patients, surgery followed by chemotherapy may be an option.

In patients with metastases (meaning the cancer has spread to other organs beyond the lungs), the traditional treatment is chemotherapy. However, with advancements in scientific research, it is now possible to identify specific mutations responsible for tumor growth.

When this happens, a targeted drug is used for treatment. For patients without this target (mutation), immunotherapy may be used alone or in combination with chemotherapy. Therefore, it is essential that each case be evaluated individually, opening up the possibility of identifying such particularities.

Types of treatment for lung cancer

Surgery: Surgery involves removing the tumor with a margin of safety, as well as removing nearby lymph nodes and those located in the mediastinum. It is the treatment of choice because it provides better results and disease control. About 20% of cases are eligible for surgical treatment. However, in the vast majority (80% to 90% of cases), surgery is not possible at the time of diagnosis due to the extent of the disease (advanced stage) or the patient’s clinical condition.

Surgery for the treatment of lung cancer can be:

• Segmentectomy and wedge resection: when a small part of the lung is removed (only the segment or part of the segment that involves the tumor). This technique is intended for patients with small tumors who cannot undergo larger surgeries due to age or limited clinical and/or respiratory conditions;

• Lobectomy: the main surgery for the treatment of lung cancer. It consists of removing the entire lobe of the lung where the tumor is located;

• Pneumonectomy: removal of an entire lung. It carries a higher risk of mortality and its indication is restricted to selected cases, being rarely used nowadays.

Chemotherapy: aims to destroy cancer cells, as well as reduce tumor growth or alleviate disease symptoms.

Radiotherapy: uses radiation to destroy cancer cells, and can be administered before (neoadjuvant) or after surgery (adjuvant), or in conjunction with chemotherapy.

Targeted therapy: this form of treatment is most suitable for patients whose tumors have specific target molecular alterations.

Immunotherapy: a strategy where the patient’s own immune system is used to combat cancer. Often, the body is unable to attack cancer because cancer cells produce proteins that help them hide from the immune system. Immunotherapy disrupts this process and helps identify and combat cancer cells.

Palliative care: approaches aimed at minimizing symptoms of any type of cancer. In lung carcinoma, it can provide relief from shortness of breath and pain, as well as the adverse effects of treatments (nausea, vomiting, or fatigue).

Prevention for lung cancer

Some actions can help reduce the risk of developing lung cancer, such as:

• Don’t start smoking;

• If you smoke, quit as soon as possible;

• Avoid being around people who smoke, as this makes you a passive smoker (by inhaling the smoke);

• Avoid exposure to chemical agents (arsenic, asbestos, beryllium, chromium, radon, uranium, nickel, cadmium, vinyl chloride, and chloromethyl ether), present in certain work environments. Always make sure to use appropriate personal protective equipment (PPE).