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Breast Imaging |
1 From the Sally Jobe Breast Centers, Radiology Imaging Associates, 8200 E Belleview Ave, Suite 102, Englewood, CO 80111 (M.A.D., S.H.P., A.J.K., A.T.S., T.I.K.); and Surgical Consultants of Aurora, Colo (S.B.C.). Received May 7, 2000; revision requested July 24; revision received August 14; accepted August 30. Address correspondence to M.A.D. (e-mail: mark.dennis@riaco.com).
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONAPPENDIXREFERENCES |
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MATERIALS AND METHODS: The findings from 600 lumps in 486 women with no focal ultrasonographic (US) mass or mammographic finding in the area of clinical concern were retrospectively studied. Evaluated parameters included the individual reporting the lump, qualitative descriptors for the physical finding, mammographic density, US characteristics in the area of concern, whether there was a change in imaging and/or physical examination results, and whether there were diagnostic biopsy findings at follow-up. The study group included 540 lumps in 435 women who had a minimum mammographic and clinical follow-up of 2 years, as well as 60 additional lumps in 51 patients who underwent biopsy.
RESULTS: No patient in the nonbiopsy group developed carcinoma at the initial site of concern during a mean mammographic and clinical follow-up period of 43 months, and all biopsy specimens were benign (negative predictive value, 100%).
CONCLUSION: Results of this retrospective study suggest that breast biopsy may be avoided in women with palpable abnormalities when both US and mammography depict normal tissue at the lump site.
Index terms: Breast • Breast, US, 00.12985, 00.12989 • Breast radiography, comparative studies, 00.11
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONAPPENDIXREFERENCES |
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In some women, the finding of a focal mammographic and/or solid ultrasonographic (US) mass corroborates the positive physical examination and prompts biopsy. In other women who present with a lump, mammographic and US findings are normal and biopsy is recommended because of the known false-negative rate of mammography, an uncertain false-negative rate for US, and the concern of missing a potentially curable cancer.
It would be desirable from cost and patient comfort and convenience standpoints to improve the low specificity of physical examination so that the number of unnecessary biopsies could be safely reduced. US has to some extent enabled this to be accomplished when the lump is shown to represent a cyst or solid benign mass (5). However, to our knowledge, there is little published information addressing the management of lumps in the sizeable group of women who have normal mammograms and normal sonograms (6,7). Therefore, biopsy avoidance based on negative imaging results has not been widely accepted. In this retrospective study, we reviewed our experience with patients who presented with breast lumps and had normal mammograms and normal sonograms.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONAPPENDIXREFERENCES |
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The study cases were retrospectively identified by querying the radiology information system billing module for all breast sonograms obtained from 1990 to 1997. This study period was chosen to allow a mammographic and clinical follow-up period of at least 2 years throughout the duration of the data collection period and was a time when US was performed extensively for problem solving in the mammography network. The indications for breast US remained the same during the period in which the cases were collected and included nonpalpable mammographic findings and palpable abnormalities with or without focal mammographic findings.
The imaging reports were reviewed by either of two authors (A.J.K. or M.A.D.), and patients with a palpable abnormality and normal mammographic findings in the area of clinical concern were examined further. Those patients who subsequently were shown to have a focal US lesion—that is, a cyst, solid mass, or focal unusual appearing breast tissue—were excluded. Focally unusual breast tissue was defined as an appearance outside of the examining radiologist’s threshold for normal based on that individual’s experience. The remaining subgroup consisted of patients with palpable lumps, normal mammograms, and sonograms demonstrating a variety of normal breast parenchymal patterns. Patients in this group who did not have at least 2 years of clinical and mammographic follow-up or undergo biopsy were then excluded. If biopsy of the symptomatic area was performed, only 6-month clinical and imaging follow-up was required.
The ages of the patients, individuals reporting the masses, subspecialties of the referring physicians, dates of original presentation and subsequent follow-up, changes at imaging or clinical follow-up, and/or the surgery performed between the time of presentation with a lump and the time of follow-up were recorded in the study database. When available, the following physical finding descriptors that referred to the lumps also were recorded: thickening, ridge, discrete, hard, soft, vague, and painful. The area of interest was determined from the written imaging request or order form generated by the referring physician and by asking the patient to identify the lump.
Imaging
Mammography was performed with commercially available equipment: Senographe 800T and DMR (GE Medical Systems, Milwaukee, Wis), Athena HFX Plus (Fischer Imaging, Denver, Colo), Mammo Diagnost 3000 (Phillips Medical Systems, Las Palmas, Calif), M-III (Lorad, Danbury, Conn), and Alpha RT EPS (Instrumentarium, Milwaukee, Wis). The American College of Radiology accredited the breast screening network mammography sites in 1991. Mammographic density at the location of the palpable finding was classified as almost entirely fat, scattered fibroglandular density, heterogeneously dense, or extremely dense.
All sonograms were obtained by using 7.5- or 10.0-MHz linear array transducers: Logiq md 400 (GE Medical Systems), 5200 and Performa (Acoustic Imaging, Phoenix, Ariz), and Spectra (Diasonics, Milpitas, Calif). The US examinations were performed by a team that consisted of breast radiologists (A.J.K., A.T.S., M.A.D., S.H.P., T.I.K.) and highly trained multimodality breast technologists who perform screening and diagnostic mammography and breast US and assist in percutaneous breast biopsy. These multimodality breast technologists are registered mammography technologists who are trained in breast US in house at the breast center through a program of close supervision and didactic teaching that lasts 6 months to 1 year. Usually, the technologist initially performs US scanning in the patients.
During US scanning, if possible, the palpable lump was trapped between the fingers of the nonscanning hand to focus the examination, or a finger was transiently slipped under the transducer while attempting to maintain transducer contact with the breast to verify that the lump corresponded to the area demonstrated on the US monitor. If the palpable area of concern was more diffuse in nature, an effort was made to scan the entire quadrant that contained the lump.
Image Evaluation
All mammograms and sonograms were evaluated by an experienced breast radiologist at the time of patient presentation. In addition, the mammograms and sonograms obtained at presentation as well as at follow-up in each case were retrospectively reviewed by one of two of the principal investigators (A.J.K. or M.A.D.). All of the investigating radiologists had extensive experience in breast imaging and intervention.
The commonly encountered normal US tissue patterns in the areas of clinical concern were sorted into the following categories for data collection and discussion: type 1 was that of hyperechoic tissue that contained thin branching hypoechoic or anechoic structures (Fig 1); type 2, a band of hyperechoic tissue within isoechoic tissue (Fig 2); type 3, equal amounts of hyperechoic and isoechoic tissue (Fig 3); type 4, focally prominent homogeneously hyperechoic tissue (Fig 4); type 5, ovoid isoechoic structures separated by thin echogenic septa (Fig 5); type 6, a "trapped" fat lobule (ie, a compressible ovoid, isoechoic structure with thin hyperechoic horizontal lines within) surrounded by prominent hyperechoic tissue (Fig 6); and type 7, prominent tubular and/or branching hypoechoic or anechoic structures (Fig 7).
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The 3-month clinical reevaluation is believed to provide a reasonable safety net for patients who might have a neoplasm that is difficult to image. In addition, it was determined through case review by the malpractice carrier that no adverse legal consequences have resulted from a 3-month delay in breast cancer diagnosis. If at 3 months the physical examination results are still clinically bothersome, the lump is reevaluated according to the algorithm previously described. If the lump is not more prominent or worrisome at follow-up, resumption of routine screening mammographic and physical examinations at the appropriate time intervals, as well as continuation of breast self-examinations is recommended for women of screening age.
Biopsy
Tissue sampling of the palpable area with US-guided percutaneous biopsy or open surgical biopsy was performed in the women for whom there was high clinical suspicion of cancer or a high level of patient and/or referring physician anxiety. In those patients who underwent percutaneous biopsy, the area of concern at physical examination was identified by the patient and the attending breast radiologist, and a mark was placed on the skin. US guidance was performed to (a) ensure uniform delivery of the anesthetic agent over the biopsy area, (b) ensure uniform sampling of the entire area, and (c) decrease the probability of inadvertent pectoralis muscle sampling or penetration with pneumothorax.
Automated 14-gauge large-core biopsy needles (Monopty or MaxCore; Bard International, Covington, Ga) were used to obtain tissue samples. The lumps were trapped between the transducer and the fingers of the stabilizing hand. With this technique, the transducer is rotated slightly between core samples without translating the position on the skin surface; this allows sequential harvesting of different contiguous regions of tissue in a three-dimensional fanlike distribution throughout the palpable area. This technique thereby prevents redundancy in biopsy samples and ensures uniform coverage of the area. Occasionally in the present study, in the cases of a discrete small lump, a vacuum-assisted biopsy needle (Mammotome; Ethicon Endosurgery, Cincinnati, Ohio) was used to acquire tissue. A benign percutaneous biopsy result, when combined with unchanged unilateral 6-month postbiopsy US and mammographic findings, was considered to be very strong evidence of a benign lump. In cases in which further information was desired but the patient was averse to biopsy as the next step, magnetic resonance (MR) breast imaging was offered. Lack of suspicious enhancement in the area of the lump at MR breast imaging was strong corroborative evidence that the palpable lump represents normal tissue (8,9).
Statistical Analyses
Statistical evaluation was performed by using contingency tables with a two-tailed Fisher exact test. In one table (US descriptors), a 
2 test was performed because exact calculations were particularly time intensive. In this case, the 2 test results were valid with regard to meeting the assumptions of the test. A P value of less than .05 was considered to be statistically significant. All tests were performed by using the SAS/STAT software system (user’s guide program, version 6, fourth edition, volume 1, 1989; SAS Institute, Cary, NC).
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONAPPENDIXREFERENCES |
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Biopsy was performed on 60 palpable lumps in 51 patients with negative US and mammographic findings. The mean age of the patients at biopsy was 45 years compared with the overall mean age of patients at presentation with all lumps of 47 years. In 12 (20%) of the 60 lumps in the biopsy group, surgical biopsy was performed, and in 48 (80%), percutaneous biopsy was performed. Neither atypia nor neoplasia was found at biopsy in any patient. Follow-up data were available in 39 (81%) of the 48 lumps in the percutaneous biopsy group, with a mean follow-up of 39 months (range, 6–85 months). Twenty-eight (72%) of these 39 lumps were followed for longer than 24 months.
Information regarding the individual who reported the mass was available for 265 (44%) of the 600 lumps. For 125 (47%) of these 265 lumps, it was the patient who reported the mass; for 120 (45%) lumps, the patient’s physician; for 16 (6%) lumps, both the patient and the physician; and for four (2%) lumps, the mammography technologist. When the lumps that led to biopsy were compared with those that did not (Table 1), the difference in reporters of the mass was not statistically significant (P = .89).
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In this study of 600 retrospectively evaluated breast lumps, the negative predictive value of a normal mammogram and normal sonogram was found to be 100%.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONAPPENDIXREFERENCES |
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Approximately 70%–80% of all biopsies prompted by imaging findings are performed for what is ultimately found to be a benign entity (10), and, as discussed earlier, approximately 90% of biopsies performed in patients with lumps and normal mammograms and without US characterization can be expected to yield benign results. These data, combined with the increasing number of women presenting for evaluation, indicate that there is an expanding number of retrospectively unnecessary biopsies (ie, performed for a benign entity). Although the use of less invasive histologic biopsy techniques (eg, imaging-guided automated large-core biopsy and vacuum-assisted large-core biopsy) yields accurate diagnoses at substantially decreased costs, as compared with open surgical biopsy (11,12), the costs attributed to unnecessary biopsy continue to rise.
If the societal cost of breast biopsy is to be reasonably controlled, other medically acceptable, cost-conscious measures will need to be taken. One logical step would be the implementation of measures to limit the number of unnecessary biopsies. This has been accomplished in several ways. First, surgical consultation can be used as an additional level of triage. Second, periodic mammographic and physical examination surveillance in the subset of patients with mammographically "probably benign" masses can be performed instead of biopsy (13). Third, biopsy or interval mammographic surveillance can be obviated when simple cysts are shown to be the cause of the lump. Fourth, US can enable one to classify solid lesions into benign, indeterminate, and malignant categories (5), giving physicians and patients the option of averting biopsy if a palpable and/or mammographic finding was characterized as a benign solid lesion at US.
As addressed in this study, now it may be possible to avoid performing biopsy in women who present with a palpable breast lump and have a normal mammogram, by performing US. This latter concept is not new. Guyer and Dewbury (6) noted that only four of 121 patients with breast lumps, normal mammograms, and benign breast tissue at US were found to have cancer at biopsy. In another study, Logan-Young et al (14) observed a cancer prevalence of only 0.3% in 2,248 patients with lumps and normal imaging findings; in an editorial, these authors commented that US was helpful in canceling unnecessary biopsies (7). Finally, Kopans et al (15) and Soo and Rosen (16) reported excellent negative predictive values when both US and mammography were normal in the setting of a lump.
Whether biopsy avoidance as described in this study can be applied with success in nonsubspecialized radiology practices is yet to be determined. US is highly operator dependent, and technically thorough US examination with excellent near-field transducers is required to exclude invasive breast carcinoma with reasonable confidence. Knowledge of the US appearances of normal breast tissue and benign and malignant masses is required as well. Potential cancer misses due to operator error at real-time US can most likely be minimized with specific training of radiologists and technologists in breast US. This complete breast imaging team approach can establish a stable "double-read" environment that is anchored by either a multimodality breast technologist or a breast radiologist in the breast center at all times. By definition, the term "double-read" implies the participation of two individuals, and we believe that real-time evaluation by the breast radiologist is mandatory in cases in which the initial technologist assessment is "normal" in the area of the lump. We believe also that the benefit of this subspecialized team approach is substantiated by the 100% negative predictive value of US in this study.
Finally, it should be noted that hard lumps accounted for only 2% of the total palpable finding descriptors, and surgical referral accounted for only 5% of the lumps in this study. Although we believe that with experience in breast US, the diagnosis of cancer, if present, can be made reliably in these higher risk clinical subgroups as well, it may be desirable to perform biopsy rather than follow up these patients, especially during the early phases of incorporating biopsy-averting US into a breast health practice.
The method of evaluating breast lumps discussed in this study can provide a mechanism by which breast radiologists aid primary care physicians and/or surgeons in conservatively managing a common problem in their practices without the patient inconveniences and discomfort and the costs associated with further referral and/or biopsy. It must be emphasized, however, that despite the excellent results obtained in our practice setting, a normal sonogram should never preclude biopsy in the setting of high clinical suspicion. Despite this caveat and the need for a large prospective trial of US used as described to confirm the conclusions drawn, we strongly believe that radiologists and technologists dedicated to quality multimodality breast imaging can deliver a high level of accuracy in a reliable and reproducible fashion and thereby avoid unnecessary biopsy.
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APPENDIX |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONAPPENDIXREFERENCES |
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FOOTNOTES |
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REFERENCES |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONAPPENDIXREFERENCES |
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D. B. Kopans and M. Dennis Negative Mammographic and US Findings Do Not Help Exclude Breast Cancer * Dr Dennis responds: Radiology, March 1, 2002; 222(3): 857 - 859. [Full Text] [PDF]
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M. S. Soo, E. L. Rosen, J. A. Baker, T. T. Vo, and B. A. Boyd Negative Predictive Value of Sonography with Mammography in Patients with Palpable Breast Lesions Am. J. Roentgenol., November 1, 2001; 177(5): 1167 - 1170. [Abstract] [Full Text] [PDF]
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