Extra breast cancer imaging exams can sometimes do more harm than good.

If you had just been diagnosed with breast cancer, you'd likely agree to as many medical tests as your doctor ordered in the hopes of getting the best possible treatment. But what if less is more in this case?

A study published in the Canadian Medical Association Journal (CMAJ) in June 2015 has mapped some important trends in breast-cancer testing that you need to know about—and discuss with your doctor if you or a loved one is diagnosed.

The majority of established guidelines recommend no additional imaging or x-ray testing beyond the initial diagnosis for patients in stage I or stage II of breast cancer, because the tests' risks outweigh their benefits. Yet many doctors appear to be ignoring those protocols. (The current Cancer Care Ontario guidelines do suggest one test: a bone scan for stage II patients.)

The CMAJ study was led by Dr. Mark Clemons, a medical oncologist at the Ottawa Regional Cancer Centre, and examined data from more than 26,500 Ontario women who were diagnosed with breast cancer between 2007 and 2012.

In the CMAJ study, about 80 to 93 percent of women with stages I or II breast cancer, respectively, had had extra imaging tests done to see if the cancer has spread to other parts of the body. Many of them likely had no symptoms to warrant the additional tests. About 83,250 tests were performed in total. Dr. Clemons also found that about 24 percent of all the imaging done was of the same area of the breast, and may have been ordered simply to confirm the diagnosis.

Previous research has shown, Dr. Clemons writes, that in the majority of cases, additional tests do not find cancer has spread beyond the original diagnosis site.

He points out that the rates of finding cancer that has spread are very low (0.2 percent for stage I patients and 1.2 percent for stage II patients), and have not increased as new technologies such as magnetic resonance imaging (MRI) have become more widely available.

The risks of extra testing
On the downside, additional tests can expose women to unnecessary radiation. Also, false-positive results (small non-cancerous cells or bone spurs, for instance) can lead to unnecessary invasive procedures.

What's more, while these tests are often ordered to reassure patients that their cancer has not spread, they may have the opposite effect, causing more fear and angst, according to Drs. Daniel Rayson and Geoff Porter, the authors of a column accompanying the study report. They also point out that while breast cancer survival rates have improved "remarkably" since 1990, this is not the result of additional early testing.

They compare the practice of ordering additional tests to prescribing antibiotics for upper respiratory infections that are likely viral, not bacterial. Each is an easy way to reassure a patient, they write, "even though it is usually wrong."

The CMAJ authors all urge doctors to adhere to the less-is-more guidelines.

The bottom line? If you're diagnosed with early breast cancer, more testing may not mean better care. Be sure to discuss this with your doctor.

Read on for more on how to reduce your risk of breast cancer and what to do after a diagnosis.