What is stage 4 lung cancer?
The term stage 4 lung cancer refers to a condition where the cancer has
spread out to another lobe of the lung. Or it has affected another body
part like the liver. This type of classification into four stages is
usually done for non-small cell lung cancer.
Why is it important to know the stage of the disease? Well, staging
basically indicates how much the cancer has spread, both within the lung
and in other parts of the body. As you can imagine, this information is
critically important in deciding on the kind of treatment to adopt. This
is why doctors look at staging. Stage 4 lung cancer is a very advanced
phase of the disease.
There are different kinds of staging systems. Many doctors use a very
detailed one called the TNM staging system. This takes into account the
size of the cancerous tumor, the degree of spread to the lymph nodes as
well as to other parts of the body.
Broadly speaking, as far as non small cell lung cancer (NSCLC) is
concerned, there are four stages involved, numbered from 1 to 4. Stage 1
NSCLC is when the cancer is entirely localized in a small area of the
lung. This is the most treatable stage of the cancer and survival rates
are relatively high when compared to the other three stages.
This stage is divided into two sub stages - 1A and 1B. Stage 1A refers to
cases where the tumor is less than 3 cms in size. Stage 1B includes
cancers larger than 3 cms (but still relatively small), cancers that have
caused a partial collapse of the lung and those that have affected the
inner lung covering.
Stage 2 lung cancer likewise has two phases - 2A and 2B. The former means
that the cancer has affected lymph nodes adjoining the lungs. In stage 2B,
the cancer is larger than 3 cms across and has affected the lymph nodes.
It can also mean that the cancer has not affected the lymph nodes but has
affected the diaphragm, the lung's outer covering or the chest wall
Stage 3A in non small cell lung cancer can mean that the cancer is
localized on one side of the chest but has affected the lymph nodes that
are located further away from the lung. This stage also covers a condition
where only the lymph nodes nearest the lung are affected but the chest
wall or the middle portion of the chest have been afflicted.
Stage 3B can mean a number of things. There is a fluid collection around
the lung - if this contains cancerous cells, it may be classified as stage
3B. Alternatively, there may be two or more cancer tumors in the affected
lung lobe. It could also mean that the cancer has spread to points above
the collarbone. Or that it has affected another major part of the chest
like the windpipe, a large blood vessel, etc.
Stage 4 lung cancer is the final stage involved. Here, the cancer could
have affected another body organ like the liver, the bones, etc. Or it
could have struck another lobe of the lung. It has progressed beyond a
single localized tumor.
Both non small cell lung cancer and small cell lung cancer can, in theory,
be classified into the four stages above. However, small cell lung cancer
spread fast and early. So it is usually divided into just two stages
instead of four as above.
It is best to diagnose the disease well before it progresses to become
stage 4 lung cancer. Early detection is the key to successful treatment.