Thank you for your query on Healthcare Magic.
Nothing to worry.
Cough is a only a symptom of respiratory tract
, or irritation.
Low WBC count
is seen in viral illnesses most commonly and it is not a finding of cancer.
I advise you to stop worrying about the cancer and repeat the test as advised by your pediatrician
In bacterial infections the WBC count will go up and in viral infections it will go down as a general rule.
Hope I have answered your query.