lung cancer

Lung Cancer – Its various Causes along with Symptoms, Treatments and Stages

Lung cancer is the rapid growth of abnormal cells in the lung. It can start anywhere in the lungs and affect any part of the respiratory system.

It is the leading cause of cancer deaths in the United States, among both men and women. It claims more lives than colon, prostate, lymph and breast cancer combined.

Most of these lung cancer deaths could be prevented as smoking accounts for nearly 90 percent of the cases.

Smoking is the greatest risk factor for lung cancer. Although the risk of cancer increases with the length of time and number of cigarettes one smoke’s, quitting smoking can, over time, gradually reduce the risk of developing cancer. Lung cancer is the leading cause of cancer deaths in both men and women.

Fewer than half of the people who develop lung cancer live 1 more year. And only 15% of people who develop lung cancer live for 5 more years.

Protection from exposure to other leading causes of lung cancer, such as asbestos, radon and secondhand smoke, also decreases the risk.

Prevention is critical because lung cancer usually isn’t discovered until it’s at an advanced stage when the outlook for recovery is poor. Although the survival rates for lung cancer have improved, they remain much lower than those of many other types of cancer.

Causes of Lung Cancer

The major cause of lung cancer is cigarette smoking. Other causes of lung cancer include exposure to secondhand smoke, to asbestos and other industrial carcinogens, and to high concentrations of radon — an odorless gas that’s released into the air from the breakdown of uranium in the soil and water. Smokers exposed to asbestos and radon are more likely to develop cancer than are nonsmokers.

Lung cancer that begins in the lungs (primary lung cancer) is uncommon in nonsmokers, but cancer of the breast, colon, prostate, testicle, kidney, thyroid, bone or other organs may spread to the lungs.

In that case, the cancer is still referred to by the name of the organ in which it originated, rather than being called lung cancer. There’s no connection between smoking and the spread of cancer cells to the lungs from other parts of the body.

Studies show that women have a similar risk of lung cancer as men. However, the chemicals in tobacco smoke may affect women differently than men.

Lung Cancer Symptoms

Lung cancer doesn’t cause any signs or symptoms in its earliest stages. It’s often advanced by the time it’s diagnosed. When symptoms do occur, the most common warning sign is a cough, which occurs when a tumor irritates the lining of the airways or blocks the passage of air.

A shortness of breath that may be mistaken to be a respiratory illness is also one of the common symptoms. In addition to a new cough, the other lung cancer symptoms include:

  • “Smoker’s cough” that worsens. A new cough or a cough that does not go away. Smokers who have a chronic cough from smoking may have a change in how severe their cough is or how much they cough.
  • Coughing up blood, even a small amount or bloody mucus.
  • Weight loss and loss of appetite.
  • Difficulty swallowing.
  • Swelling in the neck and face.
  • Recurring respiratory infections, such as pneumonia.
  • Chest pain ,shoulder, or back pain that does not go away and often gets worse with deep breathing
  • Shortness of breath
  • New onset of wheezing
  • Repeated bouts of pneumonia or bronchitis
  • Hoarseness that lasts more than two weeks
  • Increasing fatigue and weakness.
  • Clubbing of the fingers and toes. The nails appear to bulge out more than normal

Lung cancer spread to other parts of the body (metastasized), may cause headaches or bone pain

Type of Lung Cancer

Lung cancer is commonly divided into two types: small cell and non-small cell. Each grows and spreads in different ways and is treated differently. Small cell lung cancer spreads early in the course of the disease and occurs almost exclusively in smokers. Surgical removal usually isn’t an option for this type of cancer; instead, it’s best treated with chemotherapy and radiation. Even so, the five-year survival rate for small cell lung cancer is very low.

Non-small cell lung cancer, which is more common, accounts for more than 75 percent of lung cancers. If caught early when it’s confined to a small area, it often can be removed surgically. There are four major categories of non-small cell lung cancer:

  • Squamous cell carcinoma: This cancer forms in cells lining the airways. It’s the most common type in men.
  • Adenocarcinoma: This type of cancer usually begins in the mucous-producing cells of the lung. It’s the most common type in women and in people who have never smoked or were exposed to secondhand smoke.
  • Large cell carcinoma: This type of cancer originates in the peripheral part of the lungs.
  • Bronchoaveolar carcinoma: This uncommon type of non-small cell lung cancer tends to grow more slowly than other forms of the disease. It occurs more often in smokers than in nonsmokers and tends to arise in more than one location at the same time

Lung Cancer Treatment

Lung cancer treatment depends on the type and stage of cancer, as well as the overall health of the patient.

Treatment may include surgery to remove the cancer, radiation therapy, or medications (chemotherapy). Treatment for non–small and small cell cancer may be different.

Lung cancer treatment may include one or more of the following therapies:


Surgery is taking out the cancer. Surgery is the most effective treatment for early-stage non–small cell lung cancers (stages I and II). In some cases, only the portion of the lung that contains the tumor is removed. In others, one lobe or even the entire lung may be taken. Surgery to remove all or part of a lung often involves opening one side of the chest, a procedure called a thoracotomy.

Operations to treat lung cancer include:

  • Wedge resection: In this operation, the doctor removes only the section of the lung that contains the tumor along with a margin of normal tissue.
  • Lobectomy: The most common type of surgery, lobectomy involves removing an entire lobe of one lung.
  • Pneumonectomy: In this operation, an entire lung is removed. Because pneumonectomy will decrease lung function considerably, as well as lead to other complications, it’s performed only when absolutely necessary and then only if the patient breathing capacity is sufficient to allow breathing with a single lung.

Lung function studies and a lung scan are often done before surgery to predict whether the patient will have enough remaining lung function after surgery to live a fairly normal life.

Radiation therapy

Radiation therapy uses high-dose X-rays to kill cancer cells. Radiation therapy is often used in combination with surgery or chemotherapy or both. Radiation following surgery for stages IIA, IIB, and IIIA (with lymph node involvement) may reduce the risk of cancer returning in the chest.

The way in which radiation is delivered depends on the type and stage of the cancer being treated. Radiation therapy may be given before, during or after chemotherapy. In all cases, however, the goal of treatment is to destroy cancer cells while harming as little normal tissue as possible.

Small cell lung cancer often spreads to the brain. For that reason, the doctor may sometimes recommend brain radiation therapy to prevent cancer from metastasizing to that part of the body or to eliminate micrometastases that aren’t yet detectable with imaging studies. Brain radiation therapy can cause short-term memory problems, fatigue, nausea and other serious side effects.


Because most small cell lung cancers have spread beyond the lungs by the time they’re discovered, an operation usually isn’t a treatment option. Instead the most effective treatment is chemotherapy, either alone or in combination with radiation therapy.

Chemotherapy uses medications or drugs to kill cancer cells. Chemotherapy is the most effective treatment for small cell lung cancer, but it is only a cure in a small number of people. Chemotherapy has been shown to improve survival in non-small lung cancer when it is given after surgery for stages IB, IIA, IIB, and IIIA. It may also be used to treat more advanced stages (stages III and IV) of non–small cell lung cancer.

In cases of small cell lung cancer, chemotherapy may be used to shrink the cancer, to slow the cancer’s growth, to prevent it from spreading further, or to relieve symptoms and make the patient more comfortable (palliative care). A combination of drugs usually is given in a series of treatments over a period of weeks or months, with breaks in between so that the body can recover. Even so, because the drugs damage healthy cells along with malignant ones, they can cause serious side effects. In some serious cases, prescription drugs can cause addiction, though this is not always the case.

Targeted therapy

Targeted therapies use medications or antibodies to block growth factors that allow some cancers to grow. At this time, targeted therapies are used for advanced stages.

Lung Cancer Prognosis and Survival Rate

Prognosis and Survival Rate by stage

As with many other types of cancer, the outcome depends on how advanced the cancer is when it is diagnosed.  In other words, the stage of the cancer is very important to determine lung cancer prognosis and survival rate.

Lung cancer is one of the most difficult cancers to treat and is often diagnosed in very late stages. Because of these factors, it has one of the lowest survival outcomes when compared to any other type of cancer.

With lung cancer the likely outcome will also depend very much on its type. The statistics for small cell lung cancer are different from the statistics for non-small cell lung cancer.

Overall, of all those people diagnosed with all types of lung cancer at all stages, only about 20 out of every 100 people (20%) will be alive for 1 year after diagnosis.  About 6 out of every 100 people diagnosed (6%) will be alive for 5 years after diagnosis.  For those who are able to have surgery to remove their cancer, about 20 out of 100 (20%) are alive for 5 years later.

Non-small cell lung cancer: There are 4 main stages for non small cell lung cancer.

Stage 1: This is the earliest stage and so has the best outcome.  Depending on where the cancer is, it is often possible to remove stage one with surgery.  Unfortunately, it is not all that common for lung cancer to be diagnosed this early.  Stage 1 non small cell lung cancer is often divided into 2 stages, stage 1A and 1B.

Stage 1A about 80 out of every 100 (80%) will be alive 5 years later. Stage 1B about 60 out of every 100 (60%) will be alive 5 years later.

Stage 2: Between 40 and 50 out of every 100 people (40 – 50%) will be alive 5 years later.

Stage 3: The rates for stage 3 vary, depending on the type of treatment. And the treatment given depends on the extent of the cancer. Some people with stage 3 non small cell lung cancer can still have surgery.  Of these people 25 to 30 out of every 100 people will be alive for 5 years later.

For people who have stage 3 including cancer in the lymph nodes of the chest (mediastinum) and neck, radiotherapy and chemotherapy are the main treatments.  For those who have radiotherapy only 5 – 10 % will be alive for 5 years later.

If people with stage 3, including cancer in the chest and neck nodes, are able to have chemotherapy as well as radiotherapy, there is a slightly better outcome. Only 7 -17% will be alive for 5 years later.

Stage 4: is the most advanced stage, where the cancer has spread.  Understandably, the survival statistics are lowest for this stage.  Unfortunately, lung cancer is often diagnosed late almost at stage 4.

People diagnosed at this stage are mostly treated with chemotherapy to relieve symptoms.  About 15 – 35% treated for stage 4 will be alive a year later.  For those not fit enough to have chemotherapy treatment, this figure drops to about 10%.

On average, only 2% diagnosed with stage 4 non-small cell lung cancer would be alive for 5 years later.

Small cell lung cancer: are less common than non small cell cancers.  There are often just two stages for small cell lung cancer: Limited disease and   Extensive disease

This is because this type of cancer usually grows and spreads quite quickly.  Of all those diagnosed with small-cell lung cancer, around 1 in 3 have limited disease at the time of diagnosis.  2 out of 3 already have extensive disease at the time of diagnosis.

Of those people who have limited disease and have chemotherapy treatment for lung cancer only 35 – 40% will be alive for 2 years later.

People with extensive disease of lung cancer are also treated with chemotherapy.  But unfortunately, the survival rate is even lower.  Most only survive another 10 to 12 months.

Chemotherapy does do quite a bit to extend survival time for many people.  Without treatment, very sadly, survival time is often a matter of weeks.