Small Cell Lung Cancer

Lung cancer is the leading cause of cancer death in both men and women.

Lung cancers are divided into two main branches; small cell lung cancer(SCLC) and non-small cell lung cancer.

The main difference between SCLC and non-SCLC is aggressiveness. SCLC is much more aggressive and by the time it has been found in a patient it’s often already spread beyond the lungs.

Epidemiology

SCLC makes up about 15% of lung cancer cases. (1)

There is a higher incidence of SCLC in males and caucasians have a greater incidence compared to African Americans. (1)

Etiology

Smoking is the leading cause of 85% of lung cancer cases however, it’s most strongly associated with SCLC. (1)

While most SCLC cases arise from smokers, people who used to smoke, or people who experience second hand smoking, other risk factors are listed to the right. (2)

Workplace hazards (asbestos)
Radiation (for example from radiation therapy to treat breast cancer)
Air pollution
Family history
HIV infection
Older age

Pathophysiology

There are two subtypes of SCLC: oat cell lung carcinoma and combined-SCLC, which is SCLC with some non-small cell elements such as adenocarcinoma. (1)

Common Mutations Leading to SCLC Carcinogenesis (1):

Loss of function in RB1 tumor suppressor gene (normally regulates cell division)
Loss of function in TP53 tumor suppressor gene (normally regulates cell division)
Loss of function in FHIT tumor suppressor - in almost all SCLC cases

Stages of Small Cell Lung Cancer

Limited stage - cancer has not spread beyond the lungs or the lymph nodes above the collar bone. (2)

Extensive stage - cancer has spread beyond the lungs or lymph nodes above collar bone to other parts of the body. (2)

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(3)

Signs and Symptoms

Chest discomfort/pain
Worsening cough
Breathing problems - wheezing
Hemoptysis (coughing up blood)

Trouble swallowing
Lack of appetite
Fatigue
Weight loss

(2)

Treatment

Radiation and chemotherapy are most often used when it comes to small cell lung cancer due to its highly aggressive nature. Generally, cancers that spread fast respond better to radiation and chemotherapy.

Surgery can be used but only if the SCLC is still in the limited stage.

Additionally, smoking cessation counselling and

other supportive counselling may be given as well. (1, 4)

Prognosis

Prognosis will depend on the stage of the cancer as well as patient factors such as age, sex, and overall health. Current treatments do not provide a cure.

Localized presentation - 30% of cases

2-year survival rate of 80%, though the 5-year survival rate is still only 15%. (1)

Extensive presentation - 70% of cases

In this case the prognosis is poor. Majority of patients are dead within 24 months with a less than 2% five year survival rate despite treatment. (1)