By George Ochoa
Ultrasound should be the primary imaging modality in women aged 30 to 39 years with focal breast signs or symptoms, according to a large study (Am J Roentgenol 2012;199:1169-1177). Adjunct mammography adds little value and should be reserved for certain high-risk cases, such as patients with a highly suspicious lesion on ultrasound, a known gene mutation or a strong family history, the authors wrote.
“We studied women under [the age of ] 40 with palpable breast lumps to see how best to diagnose cancer. This hasn’t been studied carefully,” said lead author Constance D. Lehman, MD, PhD, FACR, professor and vice chair, radiology and section head, breast imaging, University of Washington, and director of imaging, Seattle Cancer Care Alliance. “This is the largest study to date, of breast ultrasound and adjunct mammography in women 30 to 39 years of age, who present with focal breast signs or symptoms of cancer in the United States.”
In the retrospective, single-center study, the researchers identified all women aged between 30 and 39 years who underwent ultrasound examination with corresponding mammography for focal breast signs or symptoms, between Jan. 1, 2002, and Aug. 31, 2006. The number of cases identified was 1,208 in 954 patients (mean age, 35 years; age range, 30-39 years). Outcomes were benign in 1,185 (98.1%) cases and malignant in 23 (1.9%). Ultrasound discovered 22 of the 23 cancers, whereas mammography discovered only 14 of 23. Breast ultrasound proved to have 95.7% sensitivity for cancer detection at the site of focal breast concern (89.2% specificity; 99.9% negative predictive value [NPV]; and 13.2% positive predictive value [PPV]). Mammography had a sensitivity of 60.9%, (specificity 94.4%; NPV 99.2%; and PPV 18.4%). Mammography also detected one additional malignancy in an asymptomatic area in one patient who was subsequently found to have a breast cancer type 2 susceptibility protein (BRCA2) gene mutation.
“Before our study, in the United States we were doing mammography first in women aged 30 to 39,” said Dr. Lehman. “We found that best practice is to start with ultrasound. Ultrasound is the better primary tool for these women.” The current American College of Radiology (ACR) Appropriateness Criteria, for women aged 30 years or older with a palpable breast mass, recommends using mammography as the first imaging modality, followed by ultrasound. Dr. Lehman said the criteria should be revised: “ACR is reviewing our data and other available evidence, and considering changes to their guidelines.”
Andrew D. Seidman, MD, attending physician, Breast Cancer Medicine Service, Memorial Sloan-Kettering Cancer Center, and professor of medicine, Weill Cornell Medical College, New York City, who is not associated with the paper, commented by email: “It is an important study because it represents the largest analysis of the utility of ultrasonography and diagnostic mammography in patients between 30 to 39 years of age who present with breast signs or symptoms. It suggests that a change in guidelines and practice is warranted, specifically that ultrasound should be the first ‘go-to’ radiologic examination, and that mammography might be largely abandoned for patients in this age group, in this specific clinical scenario.”
Of the study’s limitations, Dr. Lehman said, “It’s a single-site study. And the ultrasound was performed by radiologists specialized in the use of breast ultrasound.”
Additional limitations observed by Dr. Seidman include the retrospective nature of the study and its insufficient “special handling” of patient subgroups at higher baseline risk for breast cancer or ductal carcinoma in situ.
Dr. Seidman did not agree that the current ACR Appropriateness Criteria should be revised on the strength of this study. “While it would appear that mammography may indeed add very little to ultrasonography for the woman aged 30 to 39 who presents with breast signs or symptoms, it is hard for me to imagine that, under such circumstances, patients and their physicians will forgo mammography. The time of breast pain, or a lump, is an anxious moment for most women, and a retrospective, single-institution study, no matter how robust, does not seem sufficient to either change guidelines nor dissuade patients and their physicians from proceeding with mammography, or even MRI [magnetic resonance imaging], for that matter.”