There are 2 main types of lung cancer; the differentiation is made on the basis of histology, and the behavior, the target population and outcome varies.

1. Non small cell
2. Small cell

Non-small cell makes up 80 % of diagnosed cancers; Small cell makes up the remaining 20%.

Non-small cell lung cancer can be further subdivided into

1)   Adenocarcinoma, which is 40% of disease, and is more commonly found in non smokers or former smokers, and women

2)   Squamous cell, which is mainly found in smokers

3)   Large cell

Lung cancer is diagnosed when an abnormality is seen on a chest x-ray or chest CT scan. A biopsy is necessary, and is obtained either via a

-Bronchoscopy, in which a tube with a light is inserted through the nose and guided along the air passages for an inner visualization. Any abnormalities seen along the way are biopsied. Or,

-A needle is placed into the tumor site from the surface of the skin, after visualizing it under CT scan. This is done when the tumor is found away from the air passages, and is easier to reach from the outside.

In addition to the diagnosis of the subtype of lung cancer, the presence of mutations is tested in the cancer cell genes, e.g. k-ras. These may predict prognosis, and may be used to select patients for more targeted therapy.

After diagnosis, the next step is to plan for appropriate treatment.

-Staging: this includes CT scans of the chest, abdomen and pelvis, bone scan and MRI of the brain to detect distant disease. The presence of disease in lymph nodes between the lungs is determined by a small operation called the mediastinoscopy.

The final stage is determined by T (tumor size) N (involvement of lymph nodes) and M (presence of metastatic or distant disease). i.e. TNM.

-Performance Status determines functional state of the patient, and ability of the patient to withstand treatment

-Assessment of Lung function, to see if a portion of one lobe can be safely removed and leave enough functioning lung tissue to support normal function.

Treatment

-Surgery for early stage disease is sometimes followed by consolidation chemotherapy or radiation.

-Radiation treatment alone for early stages in patients unable to undergo surgery.

-Combination treatment with radiation + chemotherapy is used as stand-alone therapy or as a pre-surgical treatment, to shrink a locally advanced tumor, and enable potentially curative surgery.

-Chemotherapy alone, in a non-curative setting, to slow down disease progression. In this setting, it can be used in combinations or single agents, depending on the situation.

-New drugs targeting certain receptors or mutations are becoming available; their use will proliferate in the coming years.  New genetic profiles of the individual’s cancer cell will better be able to target the use of these expensive drugs in people who will actually benefit from them.

Radiation therapy is also used to alleviate pain, when disease has spread to the skeletal system. It is used to treat disease that has spread to the brain.

 

Small Cell Lung Cancer is also commonly related to tobacco use.

It behaves differently from the Non Small Cell varieties, is more rapidly growing, responds easily to radiation and chemotherapy, but has a high relapse rate.

It is mainly divided into 2 stages:

Limited stage is the only potentially curative stage. It is confined to one portion of the lung, that can be treated with a combination of radiation + chemotherapy, given simultaneously. After that, preventive radiation is given to the brain, as the disease has a high likelihood of showing up in the brain.

Extensive Stage has spread outside the range of one radiation field, and is treated with chemotherapy alone. Radiation is reserved for problem areas, and for preventive treatment to the brain. This stage does tend to progress within months, in spite of an initial good response.