Having a mole removed from your skin does not necessarily mean that you are at a high risk for skin cancer. This means that your doctor or dermatologist found an abnormal looking growth on your back and decided to take it off to be examined for abnormalities. If it comes back normal, there is nothing to worry about. If it comes back abnormal, your doctor will discuss future treatment with you. Moreover, just because a mole is abnormal it does not mean that you have skin cancer. Sometimes the doctor wishes to prevent certain growths from turning cancerous. Removal of the mole eliminates that concern.
As far as preventing future growths, the best method is to stay out of the sun's harmful rays. If you cannot stay out of the sun, definitely wear sunscreen (at least 15 on the body and on the face) and clothing that blocks the rays (light long sleeves in the hot weather). Always apply sunscreen at least 15 minutes before going in the sun. Try to avoid spending a lot of time in the sun between the hours of 10:00 AM and 2:00 PM.
This is the best and only advice to prevent skin damage from the sun. Sun damage and a family history of skin cancer can put you at a higher risk for developing skin cancer. If you have other moles watch for the following changes:
Report any concerns you may have or changes in your skin to your parents and your doctor. Keep in mind that atypical moles are fairly common and that the large majority never turns into skin cancer. For people who have had abnormal growths, it is always a good idea, in addition to checking yourself regularly, to have your skin checked once a year by a dermatologist.