Women with a history of cancer in their family are better off having MRI scans instead of mammograms

Jul 28 2004

New research by Mieke Kriege at the Department of Medical Oncology, Rotterdam Family Cancer Clinic suggests that women with a history of cancer in their family are better off having MRI scans instead of mammogram's.

These latest findings are reported in the current issue of the New England Journal of Medicine.

The Dutch researchers found that MRI scans, body pictures created using magnetic rather than x-ray energy, have an 80% success rate of detecting cancer, far higher than other tests.

Approximately 200,000 women in the United States are diagnosed with breast cancer each year, and the disease causes about 40,000 deaths annually.

About 5-10% of these cases will occur primarily because of hereditary factors. Heredity is a risk factor for some of the most common cancers, including breast, colon, ovarian, and prostate cancer.

The incidence of breast cancer rises after age 40. The highest incidence (approximately 80% of invasive cases) occurs in women over age 50.

"MRI appears to be more sensitive than mammography in detecting tumors in women with an inherited susceptibility to breast cancer," said the research team.

The sensitivity of clinical breast examination, mammography, and MRI for detecting invasive breast cancer was 17.9 percent, 33.3 percent, and 79.5 percent, respectively, and the specificity was 98.1 percent, 95.0 percent, and 89.8 percent, respectively.

The overall discriminating capacity of MRI was significantly better than that of mammography (P<0.05). The proportion of invasive tumors that were 10 mm or less in diameter was significantly greater in our surveillance group (43.2 percent) than in either control group (14.0 percent [P<0.001] and 12.5 percent [P=0.04], respectively). The combined incidence of positive axillary nodes and micrometastases in invasive cancers in our study was 21.4 percent, as compared with 52.4 percent (P<0.001) and 56.4 percent (P=0.001) in the two control groups.

"Screening by MRI led to twice as many unneeded additional examinations as did mammography, and three times as many unneeded biopsies," Kriege's team said,

But researchers said an MRI may be particularly helpful to women whose DNA harbor mutations that make them prone to breast tumors.

Mammogram's may be less effective in those women for several reasons, said Laura Liberman in a Journal editorial. One may be that tumors caused by BRCA mutations seem to grow faster. Another may be that those women tend to get cancer at a younger age, when their firmer breast tissue makes it hard to spot cancer using X-rays.

But for women with the breast cancer mutation, Liberman said, the greater sensitivity of an MRI scan may outweigh the drawback of the false positives.

"MRI may also be valuable in screening women with an increased risk due to nongenetic factors, such as prior breast cancer," she said, "but more work is needed to substantiate this possibility."

Of the 1909 women in the study, 88 underwent surgery to have their breasts removed before cancer was found out of fear that they would develop a tumor.

The American Cancer Society estimates that a woman in the United States has a 1 in 7 chance of developing invasive breast cancer during her lifetime -- this risk was 1 in 11 in 1975.

More women in the United States are living with breast cancer than any other cancer (excluding skin cancer). Approximately 3 million women in the U.S. are living with breast cancer: 2 million who have been diagnosed and an estimated 1 million who do not yet know they have the disease.

Breast cancer is the second leading cause of cancer death for women in the U.S.; approximately 40,110 women in the U.S. will die from the disease in 2004. Breast cancer is the leading cause of cancer death for U.S. women between the ages of 20 and 59, and the leading cause of cancer death for women worldwide.

Approximately 14% of women diagnosed with invasive breast cancer die from the disease within 5 years. Studies of women diagnosed with breast cancer in the past show that almost half (47%) of all women diagnosed with invasive breast cancer die from the disease within 20 years.

Older women are much more likely to get breast cancer than younger women. Most breast cancers -- about 77% -- occur in women ages 50 and older. Less than 5% of all breast cancer cases occur in women under the age of 40. However, younger women who get breast cancer have a lower survival rate than older women who get breast cancer.

Combining all age groups, white (non-Hispanic) women are more likely to develop breast cancer than black women. However, black women are more likely to die of breast cancer than white women.

Black women have a higher breast cancer mortality rate at every age, and a lower survival rate than white women.4 The five-year survival rate for white women diagnosed with invasive breast cancer is 88% while the five-year survival rate for black women diagnosed with invasive breast cancer is only 74%.

Between 1990 and 2000, the mortality rate for women of all races combined declined by 2.3% annually. In white women, breast cancer mortality declined by 2.6% annually from 1992-2000. In black women, mortality declined by 1.1% annually during the same period.5 Among both white and black women, mortality has declined faster for women under the age of 50 than for women ages 50 and older.

The current methods of treatment in use in the United States are surgery (mastectomy and lumpectomy), radiation, chemotherapy, hormone therapy, and biological therapy (including, monoclonal antibody therapy).

Mammography screening does not prevent or cure breast cancer; however, it may detect the disease before symptoms occur. Breast cancer tumors can exist for six to ten years before they grow large enough to be detected by mammography. In addition, mammography is less effective in younger women than in older women.

All women are at risk for breast cancer. About 90% of women who develop breast cancer do not have a family history of the disease.

Factors that increase a woman's risk of breast cancer include older age, earlier age at menarche, later age at menopause, nulliparity (having no children), later age at first full-term pregnancy, daily alcohol consumption, use of hormonal replacement therapy, use of the drug diethylstilbestrol (DES), postmenopausal obesity, ionizing radiation, genetic factors and family history of breast or ovarian cancer. Factors that decrease a woman's risk of breast cancer include breast-feeding and physical activity (exercise).

Although scientists have discovered some risk factors for breast cancer, the known risk factors account for only a small percentage (~ 20%) of breast cancer cases. There are no proven interventions to prevent breast cancer and there is no cure.

http://content.nejm.org/, http://www.natlbcc.org