Small cell vs. non-small cell lung cancer: What are the differences?

Small cell and non-small cell are the two types of lung cancers. Both cancers affect the lungs but they have several key differences, including how they are treated and their average progression time.

Small cell cancer is true to its name. When viewed under a microscope, the cells of a small cell cancer appear small and round. Non-small cell lung cancer cells are larger in size.

There are several different types of non-small cell lung cancers. These include adenocarcinoma, squamous cell, and large cell carcinoma.

Symptoms

Both small cell and non-small cell lung cancers cause similar symptoms. However, sometimes a person may not experience symptoms associated with lung cancer until the cancer is in its more advanced stages.

Symptoms of small cell and non-small cell lung cancer include wheezing and a persistent cough.

Examples of lung cancer symptoms include:

  • appetite loss
  • blood in mucus that has been coughed up
  • chest pain
  • cough that will not go away
  • difficulty swallowing
  • feeling tired for no apparent reason
  • shortness of breath
  • swelling, especially of the face and neck
  • wheezing

The symptoms of small cell and non-small cell cancers are largely similar. However, small cell cancers may be more likely to cause symptoms such as fatigue and weight loss because they usually spread more rapidly. A person may also experience symptoms elsewhere in their body, such as bone pain.

Causes

Risk factors and causes for both small cell and non-small cell cancer tend to be similar.

Smoking is the major risk factor for lung cancer. Smoke and the chemicals contained within it can damage the lungs, leading to cell changes that may result in cancer.

Additional causes of lung cancer can include:

  • exposure to secondhand smoke
  • exposure to previous sources of radiation
  • exposure to chemicals, such as asbestos, nickel, chromium, arsenic, soot, or tar
  • having a family history of lung cancer
  • having HIV
  • living in an area with a significant amount of air pollution

Increasing age is also a risk factor for most cancers. The longer a person lives, the more likely they are to develop cancer. This is because cancerous cells can mutate over time.

Diagnosis

Chest X-rays may be used to detect tumors and areas of scarring.

While the location of cancer cells may give doctors a clue as to the type of cancer, a doctor won’t be able to definitively say what type of lung cancer a person has until they look at cancerous cells under a microscope.

A doctor can then examine the size and appearance of the cells to determine if the cancer is small cell or non-small cell.

Examples of tests used to diagnose both types of lung cancer include:

  • Physical examination and health history: Doctors will usually ask about any symptoms a person has been experiencing as well as family history of lung-related diseases and disorders.
  • Chest X-rays: These allow doctors to look for areas of scarring or fluid buildup as well as tumors.
  • Laboratory tests: Blood and urine tests can help doctors see if other conditions could be causing a person’s symptoms.
  • CT scan: A computed tomography (CT) scan allows a doctor to see more detailed images of the lungs and to more precisely identify cancerous cells.
  • Sputum tests: Testing the mucus a person coughs up for cancerous cells can help determine if a person has cancer and what type it is.
  • Biopsy: A biopsy involves testing a small sample of potentially cancerous cells in the lungs. The test involves the removal of lung tissue, using a needle or through more invasive surgery.
  • Bronchoscopy: A special tool called a bronchoscope that has a camera on the end is inserted into the mouth or nose. Doctors can use it to look inside the lungs and take tissue samples.

Other diagnostic testing and imaging may depend upon where a doctor thinks the cancer may be.

Staging

Doctors “stage” lung cancers by how they may have spread in the body. The stages for non-small lung cancer are:

  • Occult (hidden): A doctor cannot detect cancerous cells from traditional imaging methods, but the cells have been detected in the mucus or elsewhere in the body.
  • Stage 0 (carcinoma in situ): A doctor has detected abnormal cells in the body.
  • Stage 1: Cancerous cells have formed, but the tumorhas not spread to the lymph nodes.
  • Stage 2: Cancer has either spread to the lymph nodes or is larger in size. Another determining factor for stage 2 cancer is where the cancerous cells are located.
  • Stage 3a: Cancer has spread to lymph nodes that are on the same side of the chest as the tumor. The tumor can be any size and may have spread to other areas of the chest wall, lungs, or membrane around the heart.
  • Stage 3b: The cancer has spread to lymph nodes above the collarbone or on the other side of the chest. Cancer may have spread to other areas of the body, such as windpipe, food pipe, or breastbone.
  • Stage 4: The cancerous tumor has spread to the lymph nodes and may be located in one or both lungs, found in fluid around the lungs or heart, or has spread to other body parts.

Doctors generally divide small cell lung cancers into two stages: the limited stage and the extensive stage.

The limited stage is when the cancer is only found on one side of the chest. It may involve just one lung and sometimes nearby lymph nodes.

The extensive stage is when cancer has spread to other parts of the chest and organs. However, some doctors may divide small cell lung cancer into further stages.

Can a person have both small cell and non-small cell lung cancer?

According to the Abramson Cancer Center of the University of Pennsylvania, an estimated 10 percent of people with lung cancer has both small cell and non-small cell cancers.

Studies are mixed as to whether having both cancer cell types is more difficult to treat. Other factors, such as the size of the tumor and a person’s age, may be more important considerations in determining a person’s survival rate.

Treatments

Radiation therapy is one possible treatment for both types of lung cancer.

When determining an appropriate treatment for the condition, doctors must consider a person’s unique symptoms, the type of cancer they have, and how much it has spread in their body.

Examples of treatments a doctor may use to treat both small cell and non-small cell lung cancer include:

  • Surgery to remove cancerous cells as well as lymph nodes that may be nearby. However, doctors can only safely remove a certain amount of lung tissue. If the cancer affects a large portion of the lungs, surgery may not possible.
  • Chemotherapyinvolves administering medications to treat cancer cells that are rapidly dividing.
  • Endoscopic stents can be inserted to the airways if the cancer cells have caused a portion of the airway to close.
  • Laser therapy involves using a laser beam to treat cancerous cells.
  • Radiation therapyinvolves using radiation to kill cancerous cells.

Small cell lung cancer tends to be more responsive to chemotherapy treatments than non-small cell lung cancer. Doctors may use a combination of treatments to treat lung cancer depending upon the stage and size of the tumor location.

Outlook

According to the University of Virginia Health System, small cell lung cancer is considered the more aggressive cancer when compared to non-small cell cancer.

Small cell cancers typically grow at a faster rate. An estimated 90 percent of small cell cancer patients are diagnosed when the cancer has already spread to nearby lymph nodes or organs.

Statistics on survival for different cancer types are given in terms of 5-year survival rates. These are the average percentage of people with a certain cancer type who live at least 5 years after being diagnosed.

These statistics are not absolutes. Many people live longer than 5 years while others may not.

According to the American Cancer Society (ACS), the following are 5-year survival rates for small cell lung cancer:

  • stage 1: 31 percent
  • stage 2: 19 percent
  • stage 3: 8 percent
  • stage 4: 2 percent

The ACS also provide statistics on the 5-year survival rates for those with non-small cell lung cancer:

  • stage 1a: 49 percent
  • stage 1b: 45 percent
  • stage 2a: 30 percent
  • stage 2b: 31 percent
  • stage 3a: 14 percent
  • stage 3b: 5 percent
  • stage 4: 1 percent

Other factors that may affect survival rate include whether the cancer has come back after treatment and a person’s age. Recurring cancer and advanced age both usually negatively impact survival rates.

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