There are many ways in which cancer can cause fatigue. The growth of a tumor, in general, can be taxing for your body. Other symptoms of cancer such as shortness of breath, anemia, pain, or a decreased level of oxygen in your blood (hypoxia) can cause fatigue.
A pulmonary function test may take 30 to 60 minutes to complete. This will vary according to the amount of trials necessary for you to get repeatable test results.
Lung function tests, also called pulmonary (PULL-mun-ary) function tests, measure how well your lungs work. These tests are used to look for the cause of breathing problems, such as shortness of breath. Lung function tests measure: 1  How much air you can take into your lungs.2  This amount is compared with that of other people your age, height, and sex.hese tests are used to look for the cause of breathing problems, such as shortness of breath. Lung function tests measure: 1  How much air you can take into your lungs. 2  This amount is compared with that of other people your age, height, and sex.