What is the treatment for melanoma?

DEAR DOCTOR K: My doctor just discovered that I have melanoma, but didn't really explain the treatment. Can you tell me what I'm in for?

DEAR READER: Melanoma is skin cancer that begins in the melanocytes -- cells that give skin its color. Usually these cells first form a precancerous condition called a dysplastic (diss-PLAS-tik) mole. Then the cells turn cancerous and start to reproduce aggressively.

My doctor advised active surveillance for my prostate cancer. What does this mean?

DEAR DOCTOR K: After an abnormal PSA test and biopsy, I have been diagnosed with early-stage, non-aggressive prostate cancer. My doctor advised active surveillance. What does this mean?

DEAR READER: Prostate cancer is the uncontrolled growth of abnormal cells in the prostate. This walnut-sized gland sits below the bladder, in front of the rectum, near the base of the penis. Prostate cancer is common, but it is not always dangerous. People are often surprised to hear "cancer" and "not dangerous" in the same sentence.

What should I look for when I examine my skin for melanoma?

DEAR DOCTOR K: My aunt developed the skin cancer called melanoma, and I hear that this cancer can run in families. What should I look for when I examine my skin for melanoma?

DEAR READER: Skin cancers are the most common cancers in the United States, and skin checks are an important way to identify them. You asked about the deadliest type of skin cancer, melanoma. My Harvard Medical School colleague, dermatologist Dr. Kenneth Arndt, says that more than half of melanomas are identified by patients, either alone or with the help of a partner. That's important because more than 90 percent of cases can be cured with early detection and treatment. Skin carries out many functions that help maintain health. It forms a defensive barrier, protecting inner organs from foreign invaders such as bacteria and viruses.

I have basal cell skin cancer, what will happen during Mohs surgery?

DEAR DOCTOR K: I have basal cell skin cancer on my face and am scheduled to have Mohs surgery. Can you describe what will happen during the procedure?

DEAR READER: Skin cancer is the most common cancer in the United States. Basal cell cancer is a very slow-growing type of skin cancer. It is unlikely to spread to other parts of the body, and therefore is rarely life-threatening. The most common cause of basal cell cancer is damage from sun exposure. Basal cell carcinoma begins in basal cells, which are located deep in the skin. When these basal cells turn cancerous, they invade surrounding tissues, spreading downward and outward below the skin's surface.

Is cancer caused by risky behavior or bad luck?

DEAR DOCTOR K: I thought cancer was the result of risky behaviors like smoking and spending too much time in the sun. But then I read an article about cancer and bad luck. So which is it -- behaviors or luck?

DEAR READER: I know the article you are referring to, and I wasn't very happy with the way it was presented by the media. Let me start with the bottom line: Cancer is caused by (1) our genes, and by (2) our lifestyle (risky behaviors) and environment. It's not just one or the other. Sometimes genes that we inherit from our parents cause cancer. An example is the BRCA1 gene that causes some cases of breast cancer.

What happens during a bone marrow transplant?

DEAR DOCTOR K: I have leukemia. Thankfully, a family member was a bone marrow match. Can you tell me what to expect during my bone marrow transplant procedure?

DEAR READER: A bone marrow transplant can be a life-saving treatment. To understand how it works, you need to understand how blood cells are created. And what leukemia is. Your blood contains red and white blood cells. There are several types of white blood cells, which are a key part of your immune system. All your blood cells are made by blood stem cells, which live primarily in the spongy center of your big bones.

What should I know about testicular cancer?

DEAR DOCTOR K: I'm in my 30s. A friend of mine was recently diagnosed with testicular cancer. What should I know about this cancer? Should I be screened for it?

DEAR READER: Testicular cancer is the uncontrolled growth of abnormal cells in one or both testicles (testes). Nearly all testicular cancers start in germ cells. These are the cells that make sperm. The testicles are located in the scrotum, behind the penis.

Is the home-screening test for colon cancer effective?

DEAR DOCTOR K: I heard about a new home test that detects colon cancer. Is it a good alternative to colonoscopy?

DEAR READER: The new test appears to be an advance, but I don't think it's as good as colonoscopy. Particularly for people who are at higher risk for colon cancer, I regard colonoscopy as the best test. Colon (or colorectal) cancer lies in the wall of the colon. It can cause painless bleeding. The amount of blood can be so small ("occult blood") that it isn't visible in the bowel movement, but it can be detected by chemical tests.

How does chemotherapy fight cancer?

DEAR DOCTOR K: My mother was diagnosed with cancer and will soon begin chemotherapy. I'd like to understand how chemotherapy is given, and how it fights cancer.

DEAR READER: Chemotherapy uses drugs that kill cancerous cells, but only injure healthy cells. To understand chemotherapy, you need to understand what cancer is and what is different about cancer cells.

Can an alkaline diet help prevent cancer?

DEAR DOCTOR K: I've heard that an alkaline diet can help prevent cancer. Is this true?

DEAR READER: I wish it were, but it's not. So-called alkaline diets do not fend off cancer. That's because it's nearly impossible to change your body's pH by changing what you eat. Let me back up for a minute. Every day our bodies perform any number of intricate balancing acts. One of them is to make sure the body's fluids, tissues and cells don't get too acidic or, at the other extreme, too alkaline. As you may remember from high school chemistry, acidity and alkalinity are measured as pH.