Lung Cancer Symptoms, Causes, Types, Diagnosis and Treatment


Lung cancer is a neoplasm that develops from pathologically altered epithelial cells lining the inner surfaces of the bronchi and bronchial glands. Under the influence of certain conditions, epithelial cells cease to fulfil their function. Starts an uncontrolled disorderly division process, as a result of which pathologic tissue rapidly grows, and penetrates into the nearby and then in distant organs.

The respiratory function of the lungs and other affected organs gradually decreases, intoxication with decay products increases, and in the absence of treatment there is an inevitable lethal outcome. Lung cancer is the leading cause of cancer death worldwide, accounting for the highest mortality rates in both men and women. The Global Cancer Observatory 2020 estimates released by the International Agency for Research on Cancer (IARC) indicate that lung cancer remains the leading cause of cancer deaths, accounting for 1.8 million deaths (18%) in 2020.


In lung cancer, a number of symptoms may be observed that indicate a pathologic process in the lungs. The first signs of lung cancer, most patients take for an ordinary cold, since at the initial stage of tumour growth there are no specific manifestations.

The most common symptoms are as follows:

As the pathologic neoplasm increases, the patient has:

  • A feeling of general malaise decreased efficiency.
  • Elevated body temperature.
  • Moist cough with expectoration of sputum.
  • Difficult, noisy breathing.
  • Swollen lymph nodes.
  • Frequent respiratory tract infections.

Symptoms of lung cancer in men and women are practically the same. Over time, the above manifestations are intensified; they are added to Lung cancer (Lung carcinoma)

  • Chest pain
  • Increasing during coughing and deep breaths.
  • Shortness of breath on light exertion or at rest.
  • Blood streaks or brown clots in expectorated sputum.
  • Headaches, bone pain.
  • Dizziness, occasional loss of consciousness.
  • Unexplained sudden weight loss, and loss of appetite.

If coughing, fever, or increased sputum discharge continues for more than two to three weeks, you should definitely see an oncologist for examination.

Causes And Risk Factors:

Although the causes of lung cancer and the mechanisms of malignant cell degeneration are still not precisely established, oncologists have well studied the factors that contribute to the development of the disease:

  • Smoking, including passive smoking
  • working in hazardous occupations
  • inherited predisposition to lung cancer
  • prolonged exposure of respiratory organs to radon
  • chronic respiratory diseases, including tuberculosis age over 40 years.

Men get the disease 5-6 times more often than women, as among them are much more often found heavy smokers and workers in harmful industries with high levels of dust or gas.

Types Of Lung Cancer

Two significant types are:

Non-Small Cell Lung Cancer (NSCLC):

About 80% to 85% of lung cancers are NSCLC. The adenocarcinoma, squamous cell carcinoma and large cell carcinoma are the major subtypes of non-small cell lung cancer. These subtypes, which can originate from different types of lung cells, are grouped together as “non-small cell lung cancer” because the method of treatment and prognosis are often similar.


Adenocarcinomas arise from cells that would normally secrete substances such as mucus. This type of lung cancer occurs mainly in people who smoke or have smoked, but it is also the most common type of lung cancer seen in people who do not smoke. The ratio of cancer is increased in women than in men. Compared to other types of lung cancer, it is more likely to occur in younger people. Adenocarcinoma is usually found in the outer parts of the lung and is more likely to be discovered before it has spread.

People with one type of adenocarcinoma, called adenocarcinoma in situ (in the past it was called bronchi alveolar carcinoma), usually have a better outlook than those with other types of lung cancer.

Squamous Cell Carcinoma:

Squamous cell carcinomas arise from squamous cells, which are flat cells that line the inside of the airways in the lungs. They are often associated with a history of smoking and tend to be located in the central part of the lungs, near a major airway (bronchus).

Large Cell Carcinoma (Undifferentiated Carcinoma):

Large cell carcinoma can occur anywhere in the lung and tends to grow and spread rapidly, which can make it more difficult to treat. It spreads very fast, and it has a resemblance to small-cell lung cancer.

Other subtypes: some other subtypes of non-small cell lung cancer, such as adenosquamous carcinoma and sarcomatoid carcinoma, are much less common.

Small Cell Lung Cancer (SCLC):

Small cell lung cancer usually grows and spreads much faster than non-small cell lung cancer. In most people with small cell lung cancer, the cancer has spread beyond the lungs by the time it is diagnosed. Because this cancer grows rapidly, it usually responds well to chemotherapy and radiation therapy. Unfortunately, the cancer will return at some point in most people. About 10% to 15% of all lung cancers are small cell lung cancer.

Other Types Of Lung Tumors:

In addition to the main types of lung cancer, other types of tumours can occur in the lungs.

Carcinoid Cancer:

Carcinoid cancer of the lung accounts for less than 5% of lung tumours. Most of these tumours grow slowly.

 Some other types of lung cancer are as follows:

  • Adenoid cystic carcinomas.
  • Lymphomas and sarcomas.
  • Benign lung tumors, Such as hamartomas.

These are rare. These receive different treatment than the treatment of most common lung cancers and are not addressed in this article.

Cancers That Spread To The Lungs:

 Cancers that originate in other organs (such as the breast, pancreas, kidney, or skin)can sometimes spread (metastasize) to the lungs, but these are not lung cancers. For example, cancer that starts from the breast and spreads to the lungs is called breast cancer, not lung cancer. Treatment of cancer that has spread to the lungs is based on where it originated (the primary location of the cancer).


In oncology, it is customary to distinguish the stages of lung cancer by the size of the tumour and the degree of its growth and spread to other organs. There are four main stages of the disease, depending on which method of treatment is determined.

  • A tumour with a size of no more than 3 cm is located compactly, without penetration into the pleura.  Lymph Nodes are not affected, there are no metastases.
  • The tumour enlarges and occludes the lumen of the bronchus or grows, forming a thickening within one lobe of the lung. There may be one or two metastases to regional lymph nodes.
  • The size of the neoplasm exceeds 6 cm, the pathology affects the chest wall and can reach the area of separation of the main bronchi or diaphragm.
  • Metastases penetrate into distant lymph nodes on their half of the body.  The tumour sprouts into several neighbouring organs, affects the oesophagus, heart, and stomach, and gives multiple metastases to distant lymph nodes on both sides and to other organs.

For small cell tumours, a separate classification is often used, consisting of only two stages, localized within one lung and spreading beyond the original lung, including to other organs.

Diagnosis Of Lung Cancer:

Chest X-ray:

A chest x-ray is often the first test the doctor will order to find out if there are abnormal areas in the lungs. If anything looks suspicious, he or she may order other tests. It is non-invasive and relies on the use of X-rays to generate images of the lungs.

Computed Axial Tomography (CT) Scan:

It consists of the use of X-rays from various angles to scan the structures being analyzed, take many images and, using the computer, combine them together to generate other images with great detail.  This greater detail makes it possible to detect cancer with greater precision and safety than in the case of X-rays. Finally, this test can be used to guide the performance of a needle biopsy.

Magnetic Resonance Imaging (MRI):

It is based on the use of magnetic fields generated by powerful magnets.  This type of imaging test shows the soft tissues of the body in detail and is often used to detect the possible presence of cancer metastases, for example, in the brain.

Positron Emission Tomography (PET) scanning:

The patient is administered glucose plus a radiopharmaceutical (the most commonly used is fluorine-18) which are joined together to form a traceable compound, and areas of the body with a high glucose metabolism, which is characteristic of cancer, can be detected on the scan.

Other Diagnostic Tests:

Bone scan:

An intravenous injection is administered with a radioactive substance that adheres to the damaged areas of the bones and emits a signal that allows the detection of possible bone metastases.  These imaging tests provide valuable information for the diagnosis and characterization of cancer, but it is not possible to confirm the diagnosis until a biopsy is performed and analyzed in the laboratory.

Sputum Cytology:

This consists of analyzing a sputum sample (mucus that comes out of the lungs when coughing)in search of tumour cells.  Its usefulness is limited, showing greater sensitivity in centrally located malignant lung tumours.


It consists of extracting the liquid that may have accumulated around the patient’s lungs. This fluid accumulation could be due to the spread of the cancer to the pleura, a thin lining of the lungs.  To perform this test, the area is numbed and a hollow needleis inserted between the ribs to drain the fluid for laboratory analysis. It may be repeated to make breathing easier for the patient.


A tube with a camera is introduced through the airway of the sedated patient. In this way, the trachea and bronchi can be visualized from the inside, and biopsies can be taken for subsequent laboratory analysis.  Recently, a technique called “endobronchial ultrasound scanning” (EBUS) has been developed that combines bronchoscopy with the use of ultrasound, allowing structures to be visualized in real-time and samples to be taken through a needle from complex areas, such as the lymph nodes in the centre of the thorax (from which valuable information can be extracted).

Thoracic Puncture:

It is used in cases where bronchoscopy does not allow access to the suspicious area.  It consists of a puncture with a fine needle aided by a CT scan, to take the sample from the lung and analyze it in the laboratory.


Similar to bronchoscopy, incisions are made in the patient’s chest to pass a tube with a camera, through which the physician checks the inside of the patient’s thorax and can take samples to be analyzed later.  After the test, a small hospital stay may be required for recovery.


This consists of the insertion of a camera tube between the sternum and the trachea to check the mediastinum (area between the lungs). In this way, lymph node samples can be taken directly or through a mediastinotomy (incision to facilitate sample collection).

It is important to analyze these nodes, as this is where the cancer usually spreads initially.  It also usually involves a short hospital stay. Once the tests have been performed, doctors should be able to know what stage the cancer is at and what this means for its treatment.

In addition, after the samples obtained from the pathology department are analyzed, the oncology team receives information about the histology of the tumour and whether the patient’s tumour cells have genetic alterations. Lung cancer can be non-small cell (or non-small cell) or small cell (microcytic), the latter being less frequent. The genetic alterations that can be identified in the analysis are common in cases of non-small cell lung cancer.

Some of these are known and specific treatments exist, such as alterations in the genes EGFR (between 10-20%), ALK (5%), ROS1 (1-2%), RET, BRAF etc2. There are several techniques to analyze these biomarkers, such as FISH (Fluorescent In Situ Hybridization), IHC (Immunohistochemistry) or NGS (Next-Generation Sequencing), in order to assess whether any of these “driver” alterations are present and therefore if any targeted therapy is available.


Screening tests can help detect lung cancer early, when treatment may work best.

Types of Treatment:

There are many types of treatment which depend on the type and stage of cancer. Patients who have non-small cell lung cancer are treated differently than small cell lung cancer. Non-small cell cancer patients are treated with surgery, chemotherapy, radiation therapy, targeted therapy or a combination of these treatments. Patients with small cell lung cancer are usually treated by receiving radiation therapy and chemotherapy.


 An operation where the doctor cuts away the cancerous tissue.

Chemotherapy: The tumour is shrunk or eliminated through the use of drugs. These drugs can be administered in tablets or intravenously.

Radiation Therapy:

Consists of the use of high-intensity radiation (similar to X-rays) to kill the cancer.

Targeted Therapy:

This refers to the use of drugs to block the growth and spread of cancer cells. These medications may be tablets taken by mouth or intravenous medications. Before treatment, the doctor tests the patient to see whether targeted therapy is right for the patient’s type of cancer or not.

Clinical Trials:

Clinical trials are medical research aimed at discovering new treatment options. Visit the National Cancer Institute’s clinical trials web page for more information.

Complementary and Alternative Medicine:

Complementary medicine and alternative medicine are very important because they are used in addition to treatments. Examples include acupuncture and meditation. Instead of standard treatments  Alternative medicines are used. Examples are special diets, megadoses of vitamins, herbal preparations, special teas, and magnet therapy.

Many types of complementary and alternative medicines have not been scientifically proven and may not be safe. Some complementary and alternative medicines are not effective. Always take suggestions from your doctor before using any type of complementary or alternative medicine.

Which Treatment Is Right For Me?

Choosing the right treatment for you can be difficult.  Take the opinion of your cancer doctor that which treatment options are available for your type and stage of cancer. He or she will be able to explain the risks and benefits of each treatment, as well as its side effects. Side effects are the body’s reaction to drugs or other treatments.

Sometimes people seek the opinion of more than one cancer doctor. This is called “getting a second opinion. Getting a second opinion can help you choose the treatment that is right for you.

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