Almost half of all men and a third of all women in the United States will receive a cancer diagnosis at some time in their lives. A cancer diagnosis often comes with little warning.

Here, Edward T. Creagan, M.D., a cancer specialist at Mayo Clinic's campus in Rochester, Minnesota, offers his advice on what to expect and how to cope after a cancer diagnosis.

What advice would you give someone who has just received a cancer diagnosis?

I would tell him or her to:

Know the details of the cancer diagnosis. First, find out the name of the cancer, its size and location, where it started, and if it has spread. Learn whether it's viewed as a slow-growing cancer or an aggressive one.
Ask about the available treatment options, the success rate of each treatment and what side effects to expect from each. Without that information, you can't get an accurate understanding of the problem and know what to expect from the treatment.
Bring someone with you. Know that this is a time of personal crisis, and your ability to retain any meaningful information may be practically zero.
So bring someone with you — someone who is reliable and knows how to be your advocate. Choose someone you like. It can be helpful to have someone with you to help unscramble the messages.

When should you consult a specialist in cancer diagnosis and treatment (oncologist)?

This depends on the type of cancer, its stage and the treatment options that are available.

There are many different types of cancer and not all require an oncologist. For example, some cancers, such as basal cell skin cancers, can be surgically removed and have virtually no likelihood of recurring.

Other cancers are better treated by other specialists — for example, certain thyroid tumors are better treated by thyroid specialists — as these doctors treat those types of cancers much more often than oncologists do.

For the vast majority of cancers, it's always a good idea to at least consult an oncologist to get his or her opinion. Discuss with your doctor who is the best specialist for your type of cancer.

Is it a good idea to seek a second opinion after a cancer diagnosis?

It's always reasonable to seek a second opinion from an oncologist.

You may wish to see someone at a center that specializes in cancer care. In the United States, this might be one of the National Cancer Institute-designated cancer centers around the country. Typically these centers are part of a university or large medical center.

While second opinions are reasonable, don't waste time by going to six or seven different cancer centers to see several doctors who may all tell you the same thing. If the two opinions are similar, it's likely that all other cancer specialists will tell you the same thing.

What qualities should you look for in a doctor?

Look for a doctor who:

Listens. It's important to find a doctor who will listen to your concerns. It will be easier for you to ask this doctor questions.
Explains. You want a doctor who can use plain language to explain what you have, what the treatment options are and what your prognosis is in terms you can understand.
Understands. You want that elusive quality of chemistry between you and your doctor — a doctor who understands you. If it isn't there, find someone else. He or she may have all of the credentials, but if the chemistry between you and that doctor isn't positive, you might do well to switch.

Make the relationship with your doctor a working partnership. The best treatment relationship is one where you ask questions and participate in your care.

What should you consider when discussing treatment options?

When discussing treatment options with your doctor, understand that:

Treatment is evolving. Traditionally, surgery has been the mainstay of treatment for most cancers.
More recently, there has been a movement toward less extensive operations to treat cancer.
For example, a generation ago, women with breast cancer were treated with radical mastectomy. Today, in many cases the breast is preserved by removing only the cancerous lump and a safety tissue margin around the cancer, and following this with radiation therapy and sometimes chemotherapy and hormone treatments. This approach can be as effective as more-extensive operations.
Treatment options vary. Learn about your disease and the approaches commonly used to treat it.
Some cancers respond better to radiation; others to chemotherapy or hormonal treatments. Some require one type of therapy; others a combination.
At times, simple observation rather than treatment is enough. Some cancers present few if any symptoms and cause few problems and little or no pain. They may even remain inactive for long periods of time. Treatment in those cases usually doesn't enhance your quality of life.
Other cancers are aggressive and will likely cause major problems. Treatment in those cases may be warranted.
Ask what would happen without any treatment, and compare the answer with the expected results of treatment.
Treatments have side effects. Understand what side effects to expect and what benefits the treatment offers. Then weigh your willingness to tolerate the side effects to reap the benefits.
The goals of therapy can vary, and only you can decide what side effects you're willing to accept to achieve your goal.
For example, if you're a young person with a curable disease, you may be willing to tolerate very severe, short-term side effects for a chance of eliminating your disease. But if you are 85 and have an incurable disease, you may decide not to accept bad side effects if the goal is to live only an additional month or two.

Ask your doctor what the treatment will accomplish.

For example, the doctor's statement that treatment will increase survival by 50 percent sounds great. But if 50 percent means increasing life from eight weeks to 12 weeks, and those remaining weeks are spent vomiting and battling nausea, weakness and fatigue, maybe you haven't gained much.

Don't all cancer treatments have awful side effects?

Not necessarily. Cancer treatments do have side effects, but most are predictable.

Your doctor can outline a plan to prevent many side effects and otherwise treat or lessen others.

In general, side effects are reversible, and helping you cope with them should be a focus of your doctor.

Take the potential side effects into consideration when choosing a treatment, but also know that most aren't as bad as you've heard.

Ask your doctor what you can expect:

How sick are you going to be?
How much energy are you going to have during treatment?
If you work 50 hours a week now, will you be able to work 50 hours a week during treatment? Will you be able to work 20 hours?

Find out the answers to these questions. Treatment is your decision.

What role can your family and friends play?

They may have the best of intentions, but family and friends may overwhelm you with their research efforts. And they can be overly enthusiastic in advocating aggressive treatment when they don't fully understand the side effects and outcomes.

But friends and family are crucial to survival. Numerous studies have correlated cancer survival with social contacts. But know your limits. It's OK to take a rest and regroup.

Set your priorities and acknowledge your limitations.