Annual Screening with Breast Ultrasound or MRI Could Benefit Some Women

Results of a large-scale clinical trial presented presented at the 95th Scientific Assembly and Annual Meeting of the Radiological Society of North America (RSNA) provide the first strong evidence of the benefit of annual screening ultrasound for women with dense breasts who are at elevated risk for breast cancer. In addition, the study confirmed that MRI is highly sensitive in depicting early breast cancer.

"We found that annual screening with ultrasound in addition to mammography significantly improves the detection of early breast cancer," said lead researcher Wendie A. Berg, M.D., Ph.D., breast imaging specialist at American Radiology Services, Johns Hopkins — Green Spring Station in Lutherville, Md., "and that significantly more early breast cancer can be found when MRI is performed, even after combined screening with both ultrasound and mammography. However, both ultrasound and MRI increase the risk of false-positive findings."

Women who are at high risk for breast cancer need to begin screening at a younger age, because they often develop cancer earlier than women at average risk. However, women below age 50 are more likely to have dense breast tissue, which can limit the effectiveness of mammography as a screening tool.

Multicenter trials have shown that MRI enables radiologists to accurately identify tumors missed by mammography and ultrasound. The American Cancer Society recommends that some groups of women with a high risk of developing breast cancer should be screened with MRI in addition to their yearly mammogram beginning at age 30. However, MRI is not for everyone.

"Because MRI is a very expensive test and requires intravenous contrast, it is something we only recommend for screening the approximately 2% of women who are known or likely carriers of BRCA1 or BRCA2 gene mutations or have other unusual circumstances that put them at very high risk for breast cancer," Dr. Berg said.

"There are another 10 to 15% of women who are at some increased risk because of personal history of breast cancer, family history of breast cancer and/or dense breast tissue," she added. "For many of these women, MRI is not currently justified, but annual ultrasound would be appropriate in addition to mammography."

Fig 1. This breast MRI showing focus of enhancement in left breast, negative on mammography and screening ultrasound. Pathology proven infiltrating ductal carcinoma

The researchers studied 612 women, mean age 55 years, at elevated risk of breast cancer enrolled at 14 sites in the American College of Radiology Imaging Network (ACRIN) 6666 trial funded by the Avon Foundation and the National Cancer Institute. Women underwent baseline screening mammography and ultrasound with follow-up exams at 12 and 24 months and then a single, contrast-enhanced MRI at 24 months.

Sixteen women were diagnosed with breast cancer. Twelve of the cancers were invasive, and four were ductal carcinoma in situ (DCIS). Over the course of the study, 50 to 56 percent of cancers were shown on mammography. Adding ultrasound allowed detection of 70 to 94% of cancers. Adding MRI allowed for detection of additional cancers at their earliest stage.

Fig 2. Ultrasound showing 9-mm benign mass (arrows) in upper inner quadrant

The study also found that supplemental screening with ultrasound or MRI significantly increased the risk of false-positive findings, leading to unnecessary biopsies in some women.

"It is important that women are advised of the increased potential of undergoing an unnecessary biopsy as a result of screening with ultrasound or MRI," Dr. Berg said, "but we hope this study motivates women and their doctors to learn more about their risk factors and to consider supplemental screening in addition to mammography where indicated."

Also see Abstracts:
Supplemental Yield and Performance Characteristics of Screening MRI after Combined Ultrasound and Mammography: ACRIN* 6666 *American College of Radiology Imaging Network.

CDC Awards Millions for Colorectal Cancer Screening Program

The Centers for Disease Control and Prevention (CDC) has awarded a total of $22 million to 26 states and tribal organizations to provide colorectal cancer screening services for low–income people aged 50–64 years, who are underinsured or uninsured. Colorectal cancer is the second leading cause of cancer deaths among men and women aged 50 and older in the United States.

The awards range from $358,283 to $1.1 million. The awardees are expected to begin screening patients for colorectal cancer within six months.

The states receiving five–year awards are: Alabama, Arizona, California, Colorado, Connecticut, Delaware, Florida, Iowa, Maine, Maryland, Massachusetts, Minnesota, Montana, Nebraska, New Hampshire, New Mexico, New York, Oregon, Pennsylvania, South Dakota, Utah, and Washington. The tribal organizations receiving awards are: Alaska Native Tribal Health Consortium, Arctic Slope Native Association, South Puget Intertribal Planning Agency, and Southcentral Foundation.

The funding will support screening and diagnostic follow–up care, data collection and tracking, public education and outreach, provider education, and an evaluation to measure the clinical outcomes, costs, and effectiveness of the program. The awardees can choose from among any of the recommended screenings for colorectal cancer – colonoscopy, sigmoidoscopy and stool testing.

“Colorectal cancer kills more people than any other cancer except lung cancer,” said CDC Director Thomas Frieden, M.D., M.P.H. “These colorectal cancer screening awards will save lives. We need to reach more adults aged 50 and over and others at high risk to prevent colorectal cancer.”

In 2005, more than 141,000 new cases of colorectal cancer were diagnosed and 53,000 people died from this disease. The number of new colorectal cancer cases could be reduced by as much as 90 percent if all precancerous polyps (abnormal growths in the colon or rectum), were identified using screening tests and removed before they become cancerous. However, only half of all U.S. adults aged 50 or older have been screened appropriately for colorectal cancer, and while screening rates are slowly increasing, disparities still exist. Screening rates remain higher for whites compared to all other races, for non–Hispanics compared to Hispanics, and for people with health insurance compared to those with no health insurance.

“Screening tests can detect colorectal cancer at its earliest stages, when it is most treatable,” said Laura Seeff, M.D., medical director of CDC′s colorectal cancer screening program. “This screening program has tremendous potential to address the disparities that exist in colorectal cancer screening and to save lives.”

The goals of CDC′s colorectal cancer screening program are to increase population–level screening among all persons aged 50 and older in the participating states and tribes, and to reduce health disparities in colorectal cancer screening, incidence and mortality.

For more information:

• CDC's efforts to prevent colorectal cancer
• Screen for Life

New Mammography Technology Effective in Detecting Breast Cancer

Positron emission mammography or PEM, a new technique for imaging the breast, is not affected by either breast density or a woman’s hormonal status, two factors that limit the effectiveness of standard mammography and MRI at detecting cancer, according to a study presented during the 94th Scientific Assembly and Annual Meeting (November 30 – December 5, 2008) of the Radiological Society of North America (RSNA) on Tuesday.

“The ability of positron emission mammography or PEM to detect cancer does not appear to be adversely affected by breast density, hormone replacement therapy or menopausal status,” explained the lead researcher Kathy Schilling, M.D., director of breast imaging and intervention at the Center for Breast Care at Boca Raton Community Hospital in Florida. “The sensitivity of PEM is equal to or better than breast MRI, and PEM has fewer false-positive results.”

The ability of x-ray mammography, a standard screening tool for breast cancer, to detect lesions is reduced when performed on dense breasts, where tissue is less fatty and more glandular. Breast MRI is effective at detecting cancer in dense breasts and is increasingly being used to screen women at high risk for breast cancer. However, MRI has a high incidence of false-positive test results that indicate cancer is present when it is not. Researchers believe these false positives are due in part to hormonal changes that occur during a woman’s menstrual cycle.

“Unless the MRI is performed on day seven through 14 of a woman’s cycle, reading MRI images is extremely difficult,” Dr. Schilling said. “This is a significant problem with breast MRI.” Because hormones do not have the same effect on PEM results, Dr. Schilling believes the imaging technique could play a significant role both in preoperatively evaluating breast cancer patients and in screening high-risk patients.

In the study, 208 patients with breast cancer underwent PEM, an application of high-resolution breast positron emission tomography (PET) in which a small amount of radioactive material is injected into the body to measure metabolic activity and determine the presence of disease. The researchers used a PET unit specially developed for the breast and small body parts to perform the PEM exam.

Of 189 malignant lesions imaged, PEM detected 176 for an overall sensitivity rate of 93 percent. Fifteen percent were ductal carcinoma in situ (DCIS), a noninvasive cancer confined to the ducts of the breast; 85 percent were invasive cancer.

PEM successfully detected cancer in 100 percent of fatty breasts, 93 percent of dense breasts, 85 percent of extremely dense breasts, 93 percent of women both with and without a history of hormone replacement therapy, 90 percent of pre-menopausal women and 94 percent of post-menopausal women.

According to Dr. Schilling, PEM is well tolerated by patients, who sit upright during the exam and are not alone or closely confined as they would be during an MRI exam. While breast MRI exams produce more than 2,000 images to be interpreted, PEM produces just 48 images that can be correlated with a woman’s mammogram.

“PEM is easier to use, easier to interpret and easier on the patients than MRI,” Dr. Shilling said. “It is also ideal for those patients whose MRI is difficult to interpret due to hormonal influences, women with implants, patients with metal in their bodies, or patients who suffer from claustrophobia. It is exciting that we now have a functional imaging approach with high sensitivity that complements our current anatomic imaging modalities,” she added.

Positron Emission Mammography at a Glance

• Positron emission mammography (PEM) is an effective tool for detecting breast cancer.
• Dense breast tissue and hormonal status can hinder other breast imaging techniques.
• PEM shows high sensitivity and is not limited by these factors.
• PEM, also known as high-resolution breast PET, has fewer false-positive results than breast MRI.
  

Click here to read the abstract (Effect of Breast Density, Menopausal Status, and Hormone Use in High Resolution Positron Emission Mammography).