WASHINGTON (Reuters) - MRI scans may offer a new way to detect breast cancer at its earliest stages and perhaps even prevent cancer among high-risk women, European researchers said on Thursday.
Details of a German study show that magnetic resonance imaging was better than standard mammograms, a type of X-ray, at detecting a nonmalignant tumor called ductal carcinoma in-situ, or DCIS.
This could give surgeons time to remove the lesion before it can turn cancerous.
The findings, published in the Lancet medical journal, suggest that MRI should be tested in more women to see if it should become a standard screening tool, said Dr. Carla Boetes and Dr. Ritse Mann of the Radboud University Nijmegen Medical Centre in the Netherlands.
"Although these results were unexpected, the pathophysiology of breast cancer provides ample justification for the findings," they wrote in a commentary in Lancet.
Boetes and Mann noted that autopsy results show that about 9 percent of women have undetected DCIS, and that almost all malignant breast cancer is believed to start out as DCIS.
"MRI should thus no longer be regarded as an adjunct to mammography but as a distinct method to detect breast cancer at its earliest stage," they wrote.
Dr. Christiane Kuhl, a radiologist at the University of Bonn and colleagues studied 7,319 women over five years for their study, which was also presented in June to a meeting of the American Society of Clinical Oncology.
MRI found DCIS in more than 90 percent of the 167 women with the condition, while mammograms only found 56 percent of DCIS cases.
"MRI could help improve the ability to diagnose DCIS, especially DCIS with high nuclear grade," Kuhl's team wrote.
TOO SOON TO RECOMMEND
But Debbie Saslow, director of breast and gynecologic cancer at the American Cancer Society, said it is far too soon to use MRI routinely for breast cancer screening.
"The American Cancer Society recommends that MRI screening be done annually in addition to mammography starting at age 30 for women at high risk," Saslow said in a telephone interview.
"For the most part, these are women who have had either a genetic test or found a mutation (that puts them at high risk of developing breast cancer), there is a mutation in the family, or there is a strong enough family history that would lead you to think that the risk of having a mutation is pretty high," she added.
Women who already have had breast cancer have only a moderate risk of a recurrence and are not necessarily candidates for MRI, Saslow said. The reason is that MRI is expensive -- $1,000 to $1,500 per scan -- and has a high rate of false positives, meaning it detects lesions that are harmless.
"Sometimes doctors will think they see something. With MRI it is not clear-cut," Saslow said. "Some of those women are choosing to have mastectomies."
And having an MRI does not save women from undergoing the uncomfortable mammogram process, as MRIs are always done alongside mammograms, Saslow noted. "Mammography still finds things that an MRI doesn't," she said.
Breast cancer is diagnosed in 1.2 million men and women globally every year and kills 500,000.
DCIS (ductal carcinoma in situ) is the earliest type of breast cancer. DCIS is found only in the milk duct where the cancer started. DCIS is also called Stage 0 breast cancer. DCIS can be small and hard to see on a routine screening mammogram and usually can't be felt during breast self-exam (BSE). Doctors sometimes call DCIS "precancerous" because it's non-invasive. But DCIS is associated with an increased risk of invasive breast cancer as well as cancer that spreads beyond the breast.
The study reviewed here showed that MRI (magnetic resonance imaging) was better than mammography at finding DCIS. About 90% percent of DCIS was found by MRI, while only 56% was found by a mammogram. MRI uses magnetic fields to highlight different kinds of tissues, both normal and abnormal. Mammograms use x-rays to image breast tissue.
The goal of DCIS treatment is to reduce the risk of invasive cancer in the future. In most cases, the treatment for DCIS is lumpectomy. To further lower the risk of invasive cancer, most doctors recommend radiation therapy after DCIS surgery. The risk of DCIS coming back depends on the size and "personality" of the DCIS, as well as the type of treatment. Doctors use the terms high-grade and non-high-grade to describe the "personality" of DCIS. High-grade DCIS poses a greater risk for future invasive cancer. The treatment your doctor recommends will take into account the grade of DCIS.
Since MRI appears to be better than mammograms at detecting DCIS, more women who get screening MRIs will be diagnosed and treated for DCIS. This will reduce their risk of invasive breast cancer in the future. This is why this Research News story is titled "MRI scans might prevent breast cancer, study shows."
The results of this study add to the evidence that says MRI, in some circumstances, can screen for breast cancer better than routine mammograms. Another study also showed that MRI was better than mammography at finding DCIS — particularly high-grade DCIS.
The American Cancer Society recommends using MRI for screening instead of mammography in certain women at high risk for breast cancer. This doesn't mean that screening mammograms will be replaced by MRI in all women. But your doctor may decide that your particular circumstance mean an MRI should be done instead of (or in addition to) a mammogram.
You might be wondering why MRI is not routinely recommended to screen for breast cancer in all women. There are several good reasons. First, MRI is a very sensitive test that can lead to false alarms. Past research has shown that most suspicious breast abnormalities found by MRI were NOT breast cancer. Second, an MRI for breast cancer screening is much more expensive than a mammogram. Finally, there's still much to learn about the role of MRI in routine breast cancer screening. It's quite possible that some day MRI will replace mammography, when the understanding of MRI for breast cancer screening improves and the cost of MRI decreases.
To learn more about MRI, visit the breascancer.org Screening and Testing section. To learn more about DCIS, visit the breastcancer.org DCIS pages.Breastcancer.org 7 East Lancaster Avenue, 3rd Floor Ardmore, PA 19003
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