Ask Doctor Cory.

Dear Dr. Cory:

I have always wanted to know what causes cancer. How do people get it?

Betsy

E-mail letter

Dear Betsy:

Cancer begins when normal body cells begin abnormal, out-of-control growth. They can spread and grow into tumors (TOO-mers), some of which are called malignant (mal-IG-nunt), or cancerous, and will continue to grow. Others will be benign (bee-NINE), meaning they will stop growing. Benign tumors often pose no danger, except when in sensitive spots, like the brain.

Doctors and scientists are still working on the exact cause of cancer, what causes normal cells to become abnormal. They do know that most cases of cancer are a result of several factors related to lifestyle, environment, and heredity, or the genes you inherit from your parents. (See "Dodging the Danger," this page, for more information.)

The invasion and destruction of normal tissue is the real danger of cancer. At first, cancers are often limited to one spot, or localized. Cancer at this stage is much more likely to be cured if found than cancers that have been picked up by the blood or lymphatic system and carried elsewhere in the body. Because cancer becomes harder to treat at each stage, it is important to find and treat it as early as possible.

Cancer is not contagious; you can't catch it from someone else. It can spread inside the body, but not to other people. It can occur at any age, but is most common in middle-aged or elderly people.

Dear Dr. Cory:

This magazine really goes to my brother, but I read it anyway. I find your column very interesting. As I was reading I was just wondering, do you write back to everyone who writes to you, even if their letter doesn't make it into the magazine?

Amy

Naperville, Illinois

Dear Amy:

We're glad you like the column. We try to answer as many letters as possible, but we get too many to answer each one individually. If several readers ask about the same subject, we try to answer those letters together. Or, if a classroom of students writes to us, we try to answer several of the letters in the magazine. We look for a variety of topics when we're deciding which letters to use in print.

We love getting health questions from our readers! Please keep sending letters and e-mails, everyone. Your question might be chosen for the magazine.

Sincerely,

Cory SerVaas, M.D.

DODGING THE DANGER

Experts have not pinned down the exact cause of all cancers, but they have identified plenty of actions you should take, if you can, to lower your risk of facing this deadly disease.

* Don't use tobacco--nearly a third of all cancer deaths stem from cigarettes;

* Avoid alcohol--mouth, liver, and other cancers are found more often in heavy drinkers;

* Protect your skin from the sun to avoid skin cancer;

* Test your house for radon, an invisible, odorless gas;

* Eat a balanced diet with at least five servings of fruits and vegetables each day;

* Avoid high-fat diets and eat fewer salt-cured, smoked, and nitrite-cured foods

* Keep a normal weight and get plenty of exercise.