As soon as you’re diagnosed with breast cancer, you desperately try to figure out how it could have happened. You analyze your life a thousand times over, rack your brains searching for THE reason, beat your head against the wall, experience endless guilt. All you get is a headache. Drop it! Save your precious energy for your health and well-being.

Here’s what you need to know when you’ve first received the life-changing news that you have breast cancer: First, breast cancers are as varied as the women affected by them. By looking at the many different characteristics of the cancer, you can size up its “personality” almost the way you analyze another person. Is the tumor small and low-key? Angry, aggressive, and fast-moving? Or is it very large but easy-going? Is its behavior wild and unpredictable, or does it play by the rules?

Many tests and analyses will be done over several weeks to figure out your diagnosis. The most critical test results–for your treatment and your long-term health–will tell you and your doctor:

Whether the cancer is non-invasive or invasive.
Whether lymph nodes are involved and if so, how many.

In addition, be sure that your medical team looks at these features of the cancer:

Size.
Tumor grade.
Hormone receptor status.
HER2/neu oncogene over-expression.
Margins of resection.

You can get this information at any time, and you should always ask for it. The laboratory keeps your tissue samples for a long time after surgery, so these tests can be done later in the process of diagnosis if you insist on it. You may have to wait a few days or weeks for some of these results. The wait can be long and nerve-wracking. But remember: No matter what the doctors find, they can do something to help you.

Marisa Weiss, M.D., president and founder of breastcancer.org, is a breast radiation oncologist in Philadelphia and the co-author, with her daughter Isabel Friedman, of Taking Care of Your “Girls”: A Breast Health Guide for Girls, Teens, and In-Betweens (Three Rivers Press). For more on understanding your diagnosis, go to breastcancer.org.

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