What is lung cancer
Among all neoplasms, lung cancer is the most incident type (with the occurrence of new cases) and causes the highest number of deaths worldwide. In Brazil, it is the second most common in 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, 17,760 men and 12,440 women. The disease was responsible for 26,498 deaths in 2015 in the country.
The good news is that lung cancer may have a lower incidence if you control your main risk factor, smoking. So much so that its incidence rate has been decreasing since the 1980s among males and since the 2000s among females. This occurred from awareness campaigns on the evils of smoking and passive exposure to tobacco. In approximately 85% of diagnosed cases, it is associated with the consumption of tobacco derivatives.
Lung cancer subtypes
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 type. The main subtypes of NSCLC are:
Adenocarcinoma – is the most prevalent type today. It starts in the cells that secrete substances such as mucus. This type of lung cancer mainly occurs in smokers or ex-smokers, but it is also the most common type of lung cancer seen in non-smokers. It is more common in women than men, and is more likely to occur in young people than other types of lung cancer.
Squamous cell (or spinocellular) carcinoma – starts in the squamous cells, which are flat cells that line the inside of the airways. It is usually related to smoking and is usually located in the central part of the lungs, close to the bronchus, which is the main airway in the human body; and
Large Cell Carcinoma (undifferentiated) – can arise in any part of the lung. It tends to grow and spread quickly, which makes it difficult to treat.
2) Small cell lung cancer (SCLC) – 10% to 15% of all lung cancers are SCLC, which tends to grow and spread faster than NSCLC. The multiplication of its cells makes it more sensitive to treatment with chemotherapy and radiotherapy, and its aggressiveness is related to higher rates of recurrence (return) of the disease. In addition, about 70% of people with SCLC already have metastases at the time of diagnosis.
Symptoms and signs of lung cancer
Although they may appear early in the development of the disease, symptoms of lung cancer usually do not occur until an advanced stage is reached. They are not disease specific, and the most common are:
- Persistent cough;
- Bloody sputum;
- Chest pain;
- Bone pain;
- Cephalalgia (headache);
- Shortness of breath or exacerbation thereof;
- Loss of weight and appetite;
- Recurrent pneumonia or bronchitis;
- Pleural effusion (abnormal accumulation of fluid in the pleura);
- Feeling tired or weak;
- Change in the usual rhythm of coughing in smokers, in which attacks occur at unusual times.
Lung cancer diagnosis
People who are at increased risk for lung cancer should consider having a screening test annually. According to the US Preventive Service Task Force, annual low-dose chest CT screening is suggested for adults aged 50 to 80 who are at high risk of lung cancer (smoked at least 20 packs/year) and are active smokers or former smokers who have quit smoking in the last 15 years).
For patients with suspected lung cancer, the doctor may order some of the following tests:
Chest X-ray – most common imaging test for a first attempt at diagnosis (in the face of symptoms) or for which lung cancer is detected accidentally (because it was requested for other reasons of the patient’s health). In the X-ray it is possible to see the lungs clearly and in them to visualize tumors or suspicious images that lead to a more detailed investigation, through other exams;
Biopsy – used to take a small sample of cells that will later be analyzed (to know if they are cancerous or not). Lung biopsy can be done in several ways:
- Bronchoscopy: the doctor examines the airways in the lungs using a lighted tube that goes down the throat and into the lungs;
- Mediastinoscopy: An incision is made at the base of the neck, behind the breastbone, through which surgical instruments are inserted to take tissue samples from the lymph nodes. The process is painless as it is done under anesthesia;
- Imaging-guided needle biopsy: The doctor uses imaging features such as an X-ray or CT scan to guide a needle through the chest wall and take samples of lung tissue
If the cancer is actually diagnosed, the doctor will order further tests to determine the stage it
is at, which will be helpful in choosing the treatment.
Lung cancer stages are indicated by Roman numerals ranging from I to IV, with lower stages indicating that the cancer is confined to the lung and in IV it is considered advanced and has spread to other areas of the body.
Lung cancer treatment
The treatment of lung cancer is multidisciplinary, that is, it requires a team formed by professionals from different specialties, such as oncologist, thoracic surgeon, pulmonologist, radiotherapist, interventional radiologist, nuclear doctor, nurse, physiotherapist, psychologist, nutritionist and social worker.
In patients with localized disease and without an enlarged lymph node (swelling in the ganglion) in the mediastinum (region between the two lungs), treatment is usually surgical, followed or not by chemotherapy and/or radiotherapy.
For those with disease located in the lung and lymph nodes, treatment can be done with radiotherapy and chemotherapy simultaneously, followed by immunotherapy in those who have not had disease progression (that is, it has not increased in size or spread elsewhere). In selected patients, surgery followed by chemotherapy can be used.
In patients who have metastasized (meaning that the cancer has reached other organs besides the lung), the traditional treatment is with chemotherapy. But currently, with the advancement of scientific research, it is already possible to identify specific mutations responsible for tumor growth. When this occurs, a target drug is used to treat it. For patients without this target (mutation), immunotherapy can be used with or without chemotherapy. Therefore, it is essential that each case is evaluated individually, opening the possibility of identifying such particularities.
Types of treatment
Surgery: Surgery consists of removing the tumor with a safety margin, in addition to removing the lymph nodes close to the lung and located in the mediastinum. It is the treatment chosen for providing better results and disease control. About 20% of cases are amenable to surgical treatment. However, in the vast majority (80% to 90% of cases), surgery is not possible at the time of diagnosis because of the extent of the disease (advanced stage) or the patient’s clinical condition.
Surgeries to treat 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 surrounds the tumor). This technique is intended for patients with small tumors who cannot withstand major surgeries due to age or limited clinical and/or respiratory conditions;
- Lobectomy: main surgery for the treatment of lung cancer. It consists of removing the entire lung lobe where the tumor is located;
- Pneumonectomy: Removal of an entire lung. It presents a higher risk of mortality and its indication is restricted to selected cases, being little used nowadays.
Chemotherapy: aims to destroy cancer cells, as well as reduce tumor growth or reduce the symptoms of the disease.
Radiotherapy: uses radiation to destroy cancer cells, and can be done before (neoadjuvant) or after surgery (adjuvant), or together with chemotherapy.
Targeted therapy: this form of treatment is more indicated in patients whose tumors have target-specific molecular alterations.
Immunotherapy: a strategy in which the patient’s own immune system is used to fight cancer. Often, the body is unable to attack the cancer, as cancer cells produce proteins that help camouflage themselves from the immune system. Immunotherapy interferes with this process and helps to identify and fight cancer cells.
Palliative care: approaches capable of minimizing the symptoms of any type of cancer. In lung cancer, it can provide relief from shortness of breath and pain, as well as the adverse effects of treatments (nausea, vomiting, or fatigue).
Some attitudes can help reduce the risk of developing lung cancer, such as:
- Do not start smoking;
- If you are already a smoker, stop as soon as possible;
- Avoid being close to people who smoke, as this makes the person a passive smoker (by inhaling the smoke);
- Adopt a diet rich in fruits, vegetables and whole grains;
- Exercise whenever possible (if you are sedentary, start slowly and gradually increase the pace);
- 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).