Generality
Among the malignant neoplasms of the lung, non-small cell cancer is the most frequent form, accounting for about 70% of cases. This tumor originates from the epithelial tissues (which is why it is also called carcinoma) that line the bronchi and lung parenchyma.
Sometimes, patients with early stage (ie, still small) non-small cell lung cancer may not have any complaints; in these cases, the tumor may occasionally be discovered after taking, for example, a chest X-ray for other medical reasons. In the more advanced stages of the disease, on the other hand, shortness of breath (dyspnoea), chest tightness and / or bleeding with coughing (haemophtoe or hemoptysis) may occur.
During its course, non-small cell lung cancer can form a mass that obstructs proper air flow or can cause pulmonary or bronchial bleeding. In addition, the cancer can metastasize to the mediastinal, adrenal, liver, bone, and lymph nodes. brain.
Assessment of non-small cell lung cancer is based on imaging tests of the chest (such as x-rays and computed tomography) and histological analysis of specimens collected by biopsy, bronchoscopy, or thoracoscopic surgery.
Depending on the stage of the disease, treatment may include surgery, chemotherapy and / or radiotherapy.
Histological variants
Non-small-cell or non-small cell carcinomas (NSCLC) account for approximately 70% of lung malignancies.
Depending on the type of cells and tissue from which the tumor originates, different forms of disease can occur; in fact, non-small cell lung cancer can develop from the cells that make up the bronchi, bronchioles and alveoli.
Under the microscope, these tumors can be distinguished into three main histological variants:
- Adenocarcinoma: represents 35-40% of non-small cell lung cancers and can be divided, in turn, into acinar, papillary or bronchioloalveolar carcinoma; it develops at the level of the smaller caliber bronchi, therefore in a more peripheral region than the other histotypes. Adenocarcinoma is the most common lung cancer in non-smokers and is sometimes associated with the presence of lung scarring (secondary, for example, to pleurisy or tuberculous infections).
- Squamous cell carcinoma: also called squamous cell, squamous cell or epidermoid cell carcinoma; it represents 25-30% of lung cancers and arises in the airways of medium-large caliber, from the transformation of the epithelium that lines the bronchi. This form of lung cancer has the best prognosis.
- Large cell carcinoma: it is the less frequent variant (10-15% of cases); it can appear in different areas of the lung and shows a tendency to grow and spread rather rapidly.
Mixed tumors, on the other hand, are rare.
Causes
Non-small cell lung cancer is due to the rapid and uncontrolled growth of certain respiratory epithelial cells. This is the result of a "prolonged exposure to carcinogens, which act causing multiple mutations. The accumulation of these genetic alterations eventually leads to a neoplastic phenomenon (note: it has been calculated that, at the time of clinical diagnosis, in carcinomas of the lung there were 10 to 20 mutations).
As in other neoplasms, oncogenes are involved at the origin of the tumor process which: stimulate cell growth (K-ras, c-Myc), cause abnormalities in the signal transduction of the growth factor receptor (EGFR, HER2 / neu) and inhibit apoptosis (Bcl-2). In addition, over time, mutations can intervene that inhibit the tumor suppressor genes (p53), which contribute to the proliferation of abnormal cells.
Risk factors
- Tobacco smoke. Tobacco smoking is the most important predisposing factor for lung cancer: about 80% of cancers occur in smokers. The risk increases with age (the younger you are, the greater the predisposition to the disease), the number of cigarettes smoked daily, the duration of this habit, the absence of a filter and the tendency to inhale smoke. Many of the substances identified in cigarettes are potential carcinogens (including polycyclic aromatic hydrocarbons, nitrosamines, aldehydes and phenol derivatives), that is, they are able, over time, to promote the transformation of cells in a tumor sense. In addition to these components, other harmful substances have been found, such as arsenic, nickel, molds and various additives. The risk of developing non-small cell lung cancer may gradually decrease over the course of 10-15 years after cessation of the habit, but can never be comparable to that of non-smokers. The onset of cancer can also be favored by passive smoking and, only in a minority of cases, the disease occurs in those who have never smoked.
- Professional Risks. Certain types of industrial exposure increase the likelihood of developing non-small cell lung cancer. In particular, the risk is higher in case of exposure to asbestos (or asbestos) and radiation in the workplace, universally recognized as carcinogenic. An "increased predisposition to develop the disease is also found among workers exposed to nickel," to chromates, coal, nitrogen gases, arsenic, silica and beryllium.
- Air contamination. Air pollution may play a role in the current increase in incidences of non-small cell lung cancer. Recently, attention has been focused mainly on air contaminants that can accumulate indoors, such as radon, a decay product of natural radioactive elements present in soil and rocks, such as radium and uranium.
- Previous pathological conditions. Some types of non-small cell lung cancer (usually adenocarcinomas) arise near areas of scarring. These can be caused by granulomatous infiltrations (tuberculosis), metallic foreign bodies or wounds that have preceded the development of the tumor. The predisposition can also increase in the presence of lung diseases (such as fibrosis and COPD) and previous radiotherapy treatments (used, for example, for a lymphoma). The lung can also be the site of metastases resulting from primary tumors of other organs (including pancreas, kidney, breast and intestine).
- Familiarity. A positive "family history can increase the risk of developing this form of cancer."
Signs and symptoms
Lung cancers remain asymptomatic for a long time in their early stages: this is the reason why they are often diagnosed in an advanced stage or are found accidentally during tests carried out for other reasons.
Signs that may indicate lung cancer include:
- Continuous cough that does not resolve or gets worse over time
- Short and / or labored breathing
- Sputum, with or without traces of blood;
- Hoarseness (if the laryngeal nerve is involved);
- Difficulty or pain when swallowing (dysphagia)
- Chest pain that increases in the case of a cough or a deep breath
- Relapsing or persistent fever, usually not elevated;
- Unexplained fatigue;
- Unwanted weight loss and / or loss of appetite;
- Swelling of the face and neck
- Digital hippocratism (fingers spread at the extremities);
- Respiratory infections (bronchitis or pneumonia) recurrent.
Possible complications
Non-small cell lung cancer can spread contiguously to nearby structures or cause metastases outside the chest.
Therefore, other symptoms may be present such as:
- Airway obstruction, pleural effusion, superior vena cava syndrome and Pancoast tumor (pain in the shoulder or arms).
- Abdominal pain, jaundice, gastrointestinal disturbances and organ failure caused by liver metastases.
- Neurological disorders resulting from the development of brain metastases, such as behavioral changes, headache, dizziness, confusion, aphasia and coma.
- Bone pain and pathological fractures from bone metastases.
Organs that can be affected by non-small cell lung cancer metastasize include the liver, brain, adrenal glands, bones, kidneys, pancreas, spleen, and skin.
Diagnosis
Diagnosis of non-small cell lung cancer first involves a "thorough medical history and a complete physical examination.
Based on the information gathered, your doctor may order further follow-up tests, such as chest x-rays, computed tomography (CT), magnetic resonance and PET (positron emission tomography, alone or in combination with CT).
Diagnosis requires cytopathological confirmation by fine needle biopsy (fine needle aspiration), bronchoscopy, or thoracoscopic surgery. The histological examination of the tissue samples thus collected allows to search for the cellular lesions typical of non-small cell lung cancer. In some cases, tumor clones can also be found in the patient's sputum.
The evaluation of pulmonary function is instead fundamental in the planning of a possible surgical intervention that foresees the removal of part of the lung.
Treatment
Generally, treatment for non-small cell lung cancer involves assessing the patient's operability, followed by a choice between surgery, chemotherapy, and / or radiation therapy. Based on the type, size, location and stage of the tumor, it is also possible to opt for a multimodal approach.
In the early stages of the disease, the reference therapeutic intervention is surgical resection with segmentectomy, lobectomy or pneumonectomy combined with mediastinal lymph node sampling or complete dissection. In these patients, surgery may be successful. Adjuvant chemotherapy after surgery. surgery is now standard practice; this approach reduces the chances of the cancer coming back (relapse).
In the more advanced stages of non-small cell lung cancer, the therapeutic protocol includes chemotherapy, radiotherapy, surgery or a combination thereof; the sequence and choice of treatment depend on the progress of the disease in the patient and on the possible presence of other concomitant pathological conditions.
Locally advanced cases that invade the heart, great vessels, mediastinum, or spine usually undergo radiation therapy.
In the terminal stages of non-small cell lung cancer, the goal is palliative care for symptom management; when treatment is not possible, chemotherapy and radiotherapy can be used to slow tumor progression and improve the quality of life.
Prognosis
Despite advances in treatment, the prognosis of non-small cell lung cancer remains unfortunately poor: only 15% of patients survive for more than 5 years from the time of clinical detection of the disease.
To improve long-term survival, it is necessary to focus attention on early diagnosis, the development of new forms of therapy and interventions to prevent the disease (eg smoking cessation, adoption of protective equipment in the workplace, screening, etc. .).
Prevention
Lung cancer prevention undoubtedly involves smoking cessation. With regard to occupational risk factors, it is important to resort to all protective measures in the workplace that allow you to minimize risks and work safely.
