Lung Cancer Summary – Lung cancer is a malignant disease that is the most common cause of death from a neoplastic entity in men. Its frequency amounts to 25/100,000 people per year. The male: female ratio is 3:1 (except for adenocarcinoma, where this ratio is 6:1 in favor of females). The disease occurs between the ages of 55 and 60, but there are cases diagnosed before age 40.
What are Lung Cancer Causes?
As with all malignant diseases, the specific cause of malignant degeneration of cells is unknown. Many carcinogenic substances have a predisposing effect. In 85% of cases, inhalation of cigarette smoke is the cause of the development of bronchial carcinoma (which is one of the histological types of carcinoma). The risk increases as the duration and quantity of cigarettes smoked increase. Potentiation of risk is when smoking is combined with exposure to occupational carcinogens (e.g. asbestos). Even passive smoking can increase the risk of malignancy.
Several groups of carcinogenic chemicals are known:
-Chromium-6-compounds – especially zinc, strontium and calcium chromate
-Arsenic compounds – arsenic acid and its salts, arsenic trioxide, etc.
-Ionizing radiations – radon, uranium
-Asbestos – chrysotile, crocidolite, amosite, anthophyllite,
-Polycyclic aromatic hydrocarbons – benzopyrene, indenopyrene
Other risk factors are genetic predisposition and the presence of pulmonary scars.
What are the Disease Changes?
According to localization, lung cancer is split into:
-Central (perihilar) carcinoma – usually small cell or squamous cell
-Peripheral carcinoma – a particular form is a Pancoast-Tobias tumor – with peak localization
-Diffuse lung carcinoma
According to the histological structure, lung cancer divides into two main types:
Small cell carcinoma (SCLC – small cell lung cancer) – has mainly a central localization and is distinguished by the most unfavorable prognosis. In 80% of cases, the tumour has already metastasized when the diagnosis is made. Often, the cells look like oat cells under a microscope (oat cell carcinoma) and may secrete hormones.
Non-small cell lung cancer (NSCLC – non-small cell lung cancer). It, in turn, can be several options:
-Squamous cell carcinoma – mainly with central localization (most common type)
-Adenocarcinoma – often with peripheral localization and is the most common form of carcinoma in non-smokers
-Broncho-alveolar carcinoma – carcinoma of alveolar cells, which is also an adenocarcinoma
-Large cell lung carcinoma
The presence of a predisposition and the action of carcinogens leads to the appearance of the tumor. The following processes occur – metaplasia of the bronchial cylindrical epithelium into squamous, followed by epithelial dysplasia and carcinoma development. Through these “steps”, squamous cell bronchial carcinoma development passes. It is also the most common association to the greatest extent with smoking.
According to the degree of differentiation, the carcinoma divides into G1 (good), G2 (medium), G3 (poorly differentiated) and G4 (undifferentiated). It metastasizes to the regional lymph nodes. Hematogenous distant metastases are often already present at diagnosis in small cell carcinoma. Common localizations are the liver, skeleton, adrenal glands, and brain.
What are the Symptoms of Lung Cancer?
In the early stage, there are virtually no complaints. Some symptoms are Cough, shortness of breath, and chest pain. Hemoptysis may also be present, but it is more often a late manifestation of the disease. The appearance of asthma or chronic bronchitis at a late age and with a short history, treatment-resistant colds, and recurrent pneumonia requires increased attention. Late manifestations of the disease are a hoarse voice (paresis of the recurrent nerve) and a pleural effusion, especially of a hemorrhagic nature.
In the rare Pancoast tumor, which affects the apices of the lungs and involves the chest wall, the cervical part of the sympathetic and nerve roots are damaged. Ultimately this leads to bone destruction of the first rib and the first thoracic vertebra, arm pain (neuralgic pain from brachial plexus involvement), the Clode-Bernar-Horner triad – unilateral miosis, eyelid ptosis, and enophthalmos.
Broncho-alveolar carcinoma is often confused with chronic pneumonia. It presents a dry, irritating cough with mucus-watery expectoration and has a poor prognosis. It is inoperable due to its diffuse spread.
Small cell carcinoma can arise from cells of the APUD (Amine Precursor Uptake Decarboxylase) system. They have the property of secreting biologically active substances and hormones. Therefore, in small cell carcinoma, the so-called paraneoplastic syndromes and endocrinopathies:
Cushing’s syndrome – due to ectopic production of adrenocorticotropic hormone:
-Syndrome of inadequate secretion and antidiuretic hormone
-Tumor hypercalcemia due to the production of parathormone-like peptides
-Lamber-Eaton syndrome – weakness in the proximal musculature of the limbs, which leads, for example, to difficulty climbing stairs;
-Polymyositis and dermatomyositis
-Paraneoplastic tendency to thrombosis
On the x-ray examination, the picture of the appearance of the tumor can be the most diverse according to localization, shape, and stages.
The radiograph can give data on:
-a rounded focus with decay
-necrotic round focus with a breakthrough to the pleural cavity
pleural effusion, etc.
Laboratory data usually show no abnormalities. Tumor markers can be tested, but they are not good at screening tests, only for therapeutic follow-up.
How is Lung Cancer Diagnosis Made?
The diagnosis is complex. Anamnestic data are often uncharacteristic. A guiding method for detecting the localization of the process is the chest X-ray. There is no form of lung shadowing that CAN NOT hide lung carcinoma. Therefore, computed axial tomography (CAT scanner) is suggested.
The diagnosis is confirmed by performing bronchoscopy and taking material for histological examination.
A diagnostic thoracotomy is performed if it is impossible to take material from tumor tissue during a bronchoscopic examination.
Diagnostic studies must be carried out to establish possible distant metastases – CT scan of the brain, echography or CT scan of abdominal organs, and bone scintigraphy.
The histological determination of the tumor and the determination of the spread of the process by imaging studies are the determining factors for the upcoming therapeutic interventions.
What Can go Wrong?
The symptoms and the chest x-ray resemble several lung diseases: pneumonia, acute and chronic bronchitis, pulmonary emphysema, COPD, bronchial asthma, upper respiratory tract infections, lung metastases from another primary focus, etc.
Treatment-resistant colds in people over 40 require all necessary diagnostic procedures to rule out lung carcinoma. Any cough that persists for more than four weeks despite treatment should be clarified.
What is the Main Lung Cancer Treatment?
Treatment includes surgery, radiation, chemotherapy and palliative care. Curative surgical resection of the tumor happens in localized non-small cell carcinoma cases. Resection is performed, accompanied by clearing of the lymphatic basins.
Since small cell carcinoma is usually already advanced at its diagnosis, surgical treatment with subsequent chemotherapy, aiming at cure, is applied only at an early stage. In some instances, combined chemotherapy and radiotherapy can be carried out preoperatively.
Small cell carcinoma is treated with radiation therapy using a megavolt technique with a dose that destroys the tumor – 50-60 Gy. In this case, the skull is also irradiated prophylactically. Polychemotherapy in combination with radiotherapy in small cell carcinoma in the case of the limited disease leads to a complete cure in 5-10% of cases.
Where there is no cure due to the stage of the disease, there is a need for palliative treatment.
It includes radiation, chemotherapy, administration of bisphosphonates in the presence of bone metastases, and analgesic preparations for cancer pain.
Lung Cancer Prevention – How to Protect Ourselves?
It is essential to avoid carcinogenic substances and smoking. Statistics show that there would be 1/3 less cancer globally if all smokers stopped smoking.
What are the Recommendations after the Diagnosis?
Prognosis depends entirely on early diagnosis. Unfortunately, nearly 2/3 of patients at diagnosis are unsuitable for surgery. The behavior and prognostic factors depend on the following:
-the histological type
-the disease stage
-the patient’s general condition
Early diagnosis of first-stage squamous cell carcinoma, for example, without lymph node involvement, predicts survival after five years in about 60% of cases. As the disease progresses (2nd – 3rd stage), this percentage sharply decreases. In the remaining histological types, the prognosis for cure is unfavorable, especially in small-cell carcinoma.