As a longtime smoker should I be screened for lung cancer?

DEAR DOCTOR K: I'm a longtime smoker. Do I need to be screened for lung cancer even if I don't have any symptoms?

DEAR READER: Until recently, my answer would have been "no." In the not-too-distant past, screening of people without symptoms -- even smokers who were at high risk -- was judged useless for lung cancer. That's because screening for lung cancer involved using standard chest X-rays, and they produced too many "false positive" results: They identified "spots" in the lungs that were harmless.

Do I have colon cancer if my doctor found a polyp during my colonoscopy?

DEAR DOCTOR K: During a screening colonoscopy, my doctor found a polyp in my colon. Does this mean I have cancer?

DEAR READER: Colon polyps are common, non-cancerous growths of tissue inside the colon, or large intestine. Some of them are benign. However, other colon polyps can progress into colon cancer. These are called adenomatous polyps.

Why does marriage have such a positive effect on patients with cancer?

DEAR DOCTOR K: I read about a study that said married cancer patients do better than those who aren't married. Why does marriage have such a positive effect?

DEAR READER: You're probably talking about a study that was published earlier this year in the Journal of Clinical Oncology. The study included about 735,000 people diagnosed with 10 different types of cancer. Married men were 23 percent less likely to die of cancer than those who were single, widowed or divorced.

Does having dense breast tissue increase my risk of breast cancer?

DEAR DOCTOR K: After my last mammogram, the doctor told me I have dense breasts. Does this increase my risk of breast cancer?

DEAR READER: A woman's breast contains different types of tissue, including fat. Women with dense breasts have relatively less fat in their breasts. Specifically, if more than 50 percent of your breasts is made up of other breast tissue (as opposed to fat), then by definition you are said to have "dense breasts." It's not uncommon: About 40 percent of women have dense breasts.

Are there lifestyle changes that can help my cancer recovery?

DEAR DOCTOR K: I'm a cancer survivor. Should I be following special guidelines for diet and exercise?

DEAR READER: Advances in cancer treatment and earlier detection are allowing more people to live longer after a cancer diagnosis. Today, more than 12 million Americans are cancer survivors. And many of them look to diet and exercise to help prevent cancer recurrence, live longer or just feel better.

How does lumpectomy plus radiation compare to mastectomy for treating breast cancer?

DEAR DOCTOR K: I was recently diagnosed with early-stage breast cancer. My doctor wants me to consider a lumpectomy plus radiation. But wouldn't a mastectomy be more effective?

DEAR READER: In a lumpectomy, just the cancer and tissue immediately around it are removed, and radiation therapy is used to kill any nearby cancer cells that might not have been removed. In a mastectomy, the whole breast is removed. Since sometimes breast cancer cells (invisible to the eye of the surgeon) can spread into the surrounding breast, it's plausible to think that a mastectomy might have a better cure rate than just a lumpectomy.

Should I take tamoxifen longer than five years?

DEAR DOCTOR K: I was diagnosed with ER-positive breast cancer a few years ago. My doctor told me to take tamoxifen for five years to prevent my cancer from coming back. I recently read that taking tamoxifen longer further decreases the risk of a cancer recurrence. What should I do?

DEAR READER: The simple answer is: Ask your primary care doctor if you should talk to a breast cancer specialist, because it may well be a good idea to continue on the tamoxifen. But I know you won't be satisfied with a simple answer, so here's a more elaborate one.

What does colonoscopy preparation involve?

DEAR DOCTOR K: I'm scheduled to have my first colonoscopy. My friends tell me the preparation is worse than the procedure. What am I in for?

DEAR READER: From my long experience as a doctor -- and as a patient -- I think your friends have it right. The large intestine (colon) is a long tube through which digested material passes. In a colonoscopy, a flexible tube with a light and camera at the end is placed inside the colon. What the doctor is looking for are abnormalities in the circular inner wall of the colon, including tumors, bleeding and inflammation.

What is leukemia and what treatments are available?

DEAR DOCTOR K: My uncle was recently diagnosed with leukemia. I'd like to learn more about it.

DEAR READER: Leukemia is a form of cancer that affects the body's blood cells. Almost every type of cell in our body can turn cancerous, and blood cells are no exception. Every day, each of us makes millions of new blood cells -- red blood cells, white blood cells, and the cells that make platelets (little cell fragments that help blood to clot). Blood cells are made in the marrow (the inside) of bones.

What should I know about being treated for breast cancer?

DEAR DOCTOR K: I was just diagnosed with breast cancer. I've found an oncologist, and she's great. Now what can I do?

DEAR READER: I'm glad you've found a great doctor. The choice of treatments depends both on the details of your cancer and your own values. For example, how important is it to preserve your breast if the doctor says removal of the whole breast has a slightly better prognosis than just removing the cancer from the breast? So I hope your doctor will take the time to get to know you and your priorities. You should feel comfortable asking your doctor questions and making decisions with her.