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1 Both authors: Breast Imaging Section, Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Ave., New York, NY 10021.
Received October 7, 1999;
accepted after revision December 14, 1999.
Presented at the annual meeting of the American Roentgen Ray Society,
Washington, DC, May 2000.
Abstract
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MATERIALS AND METHODS. We retrospectively reviewed 200 consecutive solitary nonpalpable lesions on which stereotactic 11-gauge directional vacuum-assisted breast biopsy was performed. Cost savings were calculated using Medicare reimbursements. Mammograms, histologic findings, and medical records were reviewed.
RESULTS. Stereotactic 11-gauge directional vacuum-assisted biopsy obviated a surgical procedure in 151 (76%) of 200 lesions, including 112 (73%) of 154 calcific lesions and 39 (85%) of 46 masses. Reasons for not obviating a surgical procedure in 49 lesions (25%) included recommendation for surgical biopsy in 35 lesions (18%), small carcinomas treated by excision in 10 lesions (5%), and histologic underestimation in four lesions (2%). Stereotactic 11-gauge directional vacuum-assisted biopsy decreased the cost of diagnosis by $264 per case, a 20% ($264/$1289) decrease in the cost of diagnosis compared with surgical biopsy. Of 200 lesions that had stereotactic 11-gauge directional vacuum-assisted biopsy, 106 (53%) would not have been amenable to 14-gauge automated core biopsy because of their small size, their superficial location, or inadequate breast thickness.
CONCLUSION. Stereotactic 11-gauge directional vacuum-assisted breast biopsy obviated a surgical procedure in 76% of lesions, yielding a 20% decrease in cost of diagnosis compared with surgical biopsy. Although savings per case are modest, 11-gauge directional vacuum-assisted biopsy expands the spectrum of lesions amenable to stereotactic biopsy, increasing cost savings in the population.
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Although stereotactic 14-gauge automated core biopsy is accurate and cost-effective, it has limitations. Stereotactic 14-gauge automated core biopsy is less successful in calcific lesions than in masses because of problems with calcification retrieval [12,13,14,15] and histologic underestimation of lesions containing atypical ductal hyperplasia and ductal carcinoma in situ (DCIS) [16,17,18,19]. Some investigators have excluded lesions smaller than 5 mm from stereotactic 14-gauge automated core biopsy because of the inability to reliably place a localizing marker with this method [8, 20]. Lesions that are superficial or in thin breasts may also not be amenable to stereotactic 14-gauge automated core biopsy [15, 21].
An 11-gauge directional vacuum-assisted biopsy probe has advantages in lesions in which stereotactic 14-gauge automated core biopsy is less reliable or not feasible, including lesions that are small, superficial, in thin breasts, or contain calcifications [12,13,14,15,16,17,18,19,20,21,22,23]. The cost of the 11-gauge vacuum probe is $215, and the cost of the localizing clip placed if the mammographic lesion is removed is $75; in contrast, 14-gauge automated needles cost $15-25. Few data address the cost-effectiveness of 11-gauge directional vacuum-assisted biopsy [24]. This study was undertaken to evaluate the frequency with which stereotactic 11-gauge directional vacuum-assisted biopsy obviated a surgical procedure and to calculate the cost savings attributable to that method of biopsy.
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During this period at our institution, percutaneous biopsy was offered as an alternative to needle localization and surgical biopsy for nonpalpable lesions that were suspicious or highly suggestive of malignancy unless the patient had a bleeding diathesis, the patient was unable to cooperate with the procedure, or the lesion could not be targeted. The choice of guidance technique for percutaneous biopsy was based on several factors including lesion conspicuity, equipment availability, and radiologist and patient preference. All sonographically guided core biopsies were performed with a 14-gauge automated needle, and all stereotactic biopsies were performed with a directional vacuum-assisted biopsy probe.
The preferred percutaneous biopsy method was generally sonographically guided 14-gauge automated core biopsy for masses measuring 1 cm or larger that could be seen with sonography [25, 26]; sonographically guided 14-gauge automated core biopsy was performed for 113 nonpalpable lesions during the study period. Stereotactic directional vacuum-assisted biopsy was the percutaneous biopsy method of choice for calcification lesions, masses smaller than 1 cm, or masses that were not sonographically evident. During the study period, stereotactic directional vacuum-assisted biopsy was performed in 219 lesions, using a 14-gauge probe in 19 lesions and an 11-gauge probe in 200 lesions. The latter 200 lesions constitute the basis of this study.
In these 200 lesions, stereotactic biopsy was performed on a dedicated table (StereoGuide; Lorad, Danbury, CT) with digital spot mammography, using an 11-gauge directional vacuum-assisted biopsy probe (Mammotome; Biopsys Ethicon Endo-Surgery, Cincinnati, OH). The median number of specimens obtained per lesion was 14 (range, 5-43); eight or more specimens were obtained in 194 (97%) of 200 lesions. Specimen radiography was performed for all lesions evident as calcifications. If stereotactic images obtained after completion of tissue acquisition suggested that the mammographic lesion be removed, a localizing clip (MicroMark; Biopsys Ethicon EndoSurgery) was placed at the biopsy site [20, 23]. For all lesions that had surgical excision after stereotactic 11-gauge directional vacuum-assisted biopsy, needle localization was performed, with specimen radiography to document retrieval of the lesion or the clip.
After biopsy, histologic results were correlated with imaging findings, and specific recommendations were made to the woman and her referring physician. If stereotactic biopsy yielded benign findings concordant with the imaging characteristics, the patient was referred for annual mammography. If stereotactic biopsy yielded carcinoma, the patient was referred for definitive surgery. Surgical biopsy was suggested if stereotactic biopsy revealed certain histologic findings including atypical ductal hyperplasia, radial scar, or possible phyllodes tumor; if the histologic findings and imaging characteristics were discordant; or if surgical excision was suggested by the pathologist [17, 27].
A woman was considered to have been spared a surgical procedure if stereotactic biopsy yielded a benign diagnosis for which surgical excision was neither recommended nor performed. A woman was also considered to have been spared a surgical procedure if stereotactic biopsy yielded carcinoma treated with lumpectomy and axillary dissection, lumpectomy and sentinel lymph node biopsy, or mastectomy. Women with carcinoma measuring 1 cm or larger who were treated with wide excision only were also considered to have been spared a diagnostic surgical biopsy. A woman was not considered to have been spared a surgical procedure if surgical biopsy was recommended or performed after stereotactic breast biopsy or if she had a small (<1 cm) carcinoma diagnosed at stereotactic biopsy and treated by surgical excision. A surgical procedure was not obviated if stereotactic biopsy yielded DCIS but surgery revealed infiltrating carcinoma, requiring that the patient return for a separate operative procedure to assess the axilla.
Direct costs of stereotactic biopsy (Table 1) and needle localization and surgical biopsy (Table 2) were calculated using national Medicare average allowed amounts for Current Procedural Terminology codes [28, 29] and modifiers during the first two quarters of 1999. Cost savings were calculated by subtracting the cost of diagnosis using stereotactic biopsy from the costs that would have been generated if needle localization and diagnostic surgical biopsy had been performed as the initial surgical procedure. For women with a stereotactic biopsy diagnosis of carcinoma who were spared surgery but had needle localization during breast-conserving treatment, the costs of needle localization (Current Procedural Terminology codes 19290, 19290 SG, 76096, and 76098, Table 2) were subtracted from the savings.
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Patient, lesion, and procedural data were prospectively collected by the radiologist performing the biopsy using a standardized data collection form. Each lesion was classified according to the final assessment categories of the Breast Imaging Reporting and Data System (BI-RADS) [30]. Medical records, mammographic findings, and histologic findings were reviewed, and clinical follow-up data were obtained. Data were entered into a computerized spreadsheet (Excel; Microsoft, Redmond, WA) for analysis.
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Of these 200 lesions that had stereotactic 11-gauge directional vacuum-assisted breast biopsy, 106 (53%) would not have been amenable to stereotactic 14-gauge automated core biopsy because of one or more of the following: superficial location (n = 57, 29%), inadequate breast thickness (n = 28, 14%), or lesion size less than 0.5 cm (n = 36, 18%). Of the 94 lesions in which stereotactic 14-gauge automated core biopsy would have been technically feasible, 63 were evident as calcifications. Therefore, in 169 (85%) of 200 lesions, stereotactic 14-gauge automated core biopsy was considered not technically feasible (superficial location or inadequate thickness), contraindicated (small size), or less reliable (calcifications).
Mammographic and stereotactic biopsy findings in these 200 lesions in 200 women are correlated in Table 3. Stereotactic biopsy yielded carcinoma in 42 (21%) of 200 women, including DCIS in 22 and infiltrating carcinoma in 20; these women were referred for definitive surgery. Surgery was not performed in three women because of comorbid conditions in two and patient choice in one. In the remaining 39 women, surgery was breast-conserving surgery in 31 and mastectomy in eight.
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Stereotactic biopsy obviated a surgical procedure in 28 (67%) of 42 women with cancer proven at stereotactic biopsy, including 20 (100%) of 20 women in whom stereotactic biopsy yielded infiltrating carcinoma and eight (36%) of 22 women in whom stereotactic biopsy yielded DCIS. A surgical procedure was not obviated in 14 women with DCIS found at stereotactic biopsy, including 10 with subcentimeter DCIS treated by excision and four in whom surgery revealed infiltrating carcinoma. In an additional 17 women with percutaneously proven cancer (six DCIS and 11 infiltrating carcinoma), stereotactic biopsy obviated a diagnostic surgical biopsy but did not spare the need for needle localization, which was performed at the time of therapeutic breast-conserving surgery.
Surgical biopsy was recommended after stereotactic biopsy in 35 (18%) of 200 women (Table 4). In these women, stereotactic biopsy did not obviate a surgical procedure. Surgical excision, performed in 31 of these 35 women, revealed carcinoma in five (16%).
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In 123 (62%) of 200 women, stereotactic biopsy yielded benign findings concordant with the imaging characteristics, and surgical biopsy was obviated. Follow-up data are available in 112 (91%) of these 123 women. Follow-up mammograms were performed in 82 women at a median of 13 months (range, 6-24 months) after stereotactic biopsy. In 81 of these women, mammography showed no suspicious findings; one woman developed new calcifications separate from the biopsy site 17 months after stereotactic biopsy, which proved to represent carcinoma. One woman had prophylactic mastectomy of the breast that had benign findings at stereotactic biopsy after she was diagnosed with multicentric carcinoma in her contralateral breast; the breast yielding benign findings at stereotactic biopsy also yielded benign findings at surgery. An additional 29 women who have not yet had follow-up imaging show no clinical evidence of disease (median follow-up, 15 months; range, 5-26 months).
Stereotactic 11-gauge directional vacuum-assisted biopsy obviated a surgical procedure in 151 (76%) of 200 lesions, including 39 (85%) of 46 masses and 112 (73%) of 154 calcific lesions (Table 5). A surgical procedure was not obviated in 49 (25%) of 200 lesions because of recommendation for surgical biopsy in 35 lesions (18%) (because of atypia in 20, benign lesions warranting excision in eight, and imaging-histologic discordance in seven), subcentimeter DCIS treated by excision only in 10 (5%) lesions, and failure to diagnose the invasive component of the carcinoma (histologic underestimation) in four lesions (2%).
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The mean adjusted direct cost savings per stereotactic biopsy was $264 per case. Use of stereotactic 11-gauge directional vacuum-assisted biopsy decreased the cost of diagnosis by 20% ($264/$1289) compared with the cost of surgical biopsy. Cost savings were observed in all groups of lesions, but savings were higher for masses than for calcifications, for BIRADS category 5 lesions than for category 4 lesions, and for lesions measuring 1 cm or larger than for smaller lesions (Table 5).
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Our data suggest that the 11-gauge directional vacuum-assisted biopsy device may be cost-effective in lesions unsuitable for stereotactic 14-gauge automated core biopsy. Calcific lesions are more reliably diagnosed by directional vacuum-assisted biopsy, which has a higher frequency of calcification retrieval [12,13,14,15], a lower frequency of histologic underestimation [16,17,18,19], and a lower rebiopsy rate [22]. Lesions too superficial or in breasts too thin to have stereotactic 14-gauge automated core biopsy may undergo biopsy with the vacuum method because firing the needle in the breast is not essential for tissue acquisition at directional vacuum-assisted biopsy [15, 21]. For small lesions, the 11-gauge vacuum device allows placement of a localizing marker at the lesion site [20, 23]. By increasing the proportion of lesions amenable to stereotactic biopsy, the 11-gauge device increases the potential cost savings of the procedure.
In our study, stereotactic 11-gauge directional vacuum-assisted biopsy obviated a surgical procedure in 151 (76%) of 200 lesions. Although this 76% frequency is comparable to the 76-81% frequency of obviating a surgical procedure in prior reports [8, 9, 11] of stereotactic 14-gauge automated core biopsy, it actually reflects a substantial increase in the number of women who can be spared surgery. Fewer than half (94) of the 200 lesions that had stereotactic 11-gauge directional vacuum-assisted biopsy in our study would have been amenable to stereotactic 14-gauge automated core biopsy. If stereotactic 14-gauge automated core biopsy were the only percutaneous biopsy technique available for our 200 women and if it obviated surgery in 80% of the 94 lesions amenable to it, surgery would have been spared in only 75 (80% x 94) women, or 38% of the 200 women in our study.
Stereotactic 11-gauge directional vacuum-assisted biopsy resulted in a 20% per case decrease in cost of diagnosis compared with surgical biopsy, lower than the 40-58% per case decrease in cost of diagnosis reported in previous studies of stereotactic 14-gauge automated core biopsy [8, 9, 11]. The lower cost savings per case is likely the result of several factors. First, the proportion of calcification lesions in our study was 77% versus 37-41% in previous reports [8, 11]. Others have reported a lower frequency of obviating surgery at stereotactic 14-gauge automated core biopsy of calcifications rather than masses, which is likely a result of the higher frequency among calcific lesions of failure to sample the lesion, histologic underestimation, and small DCIS lesions for which diagnosis and treatment could be potentially accomplished by a single needle localization and surgical excision [8, 11]. A second reason for the lower cost savings per case in our study is the inclusion of a high proportion of small lesions, which often required placement of a localizing clip.
Cost savings per case are also lower in our study than in prior reports of stereotactic 14-gauge automated core biopsy because of changes in reimbursement. In October 1997, the American College of Radiology recommended the use of Current Procedural Terminology code 19101 ("biopsy of breast, incisional") rather than code 19100 ("biopsy of breast, needle core") for all imaging-guided core biopsy procedures of nonpalpable lesions regardless of device [28, 29] (Table 1). The higher reimbursement for all stereotactic biopsy procedures narrows the difference in cost between stereotactic and surgical biopsy. Although the cost savings per case is less for stereotactic 11-gauge directional vacuum-assisted biopsy than for 14-gauge automated core biopsy, the 11-gauge method is applicable to a larger proportion of lesions requiring biopsy and may therefore increase cost savings in the population as a whole.
Cost savings were observed in all lesion types (masses and calcifications),
sizes (<1 cm and 
1 cm), and levels of suspicion (BI-RADS categories 4
and 5). We found higher savings in masses than in calcifications, as has been
noted by others [8,
11]. Note that the masses in
this study were a select group consisting predominantly of lesions that were
not amenable to 14-gauge automated core biopsy because they were not
sonographically evident or were too small, too superficial, or in breasts too
thin to accommodate the excursion of the automated needle. Whether 11-gauge
directional vacuum-assisted biopsy is the preferable percutaneous biopsy
method for other subgroups of masses remains to be determined. Soo et al.
[24] found that for
noncalcified masses, 11-gauge directional vacuum-assisted biopsy was 1.34
times more expensive than 14-gauge automated core biopsy. For masses amenable
to 14-gauge automated large core biopsy, cost savings may be greater with
14-gauge automated large core biopsy (particularly under sonographic guidance)
than with 11-gauge directional vacuum-assisted breast biopsy
[24,
26].
Contrary to prior reports of stereotactic 14-gauge automated core biopsy, we found stereotactic 11-gauge directional vacuum-assisted biopsy to have high efficacy in evaluating BI-RADS category 5 calcifications. The frequency of obviating surgery in women with BI-RADS category 5 calcifications was 90% in our study versus 42-55% in prior reports of stereotactic 14-gauge automated core biopsy [11, 32]. The improved performance of 11-gauge directional vacuum-assisted biopsy in BI-RADS category 5 calcifications likely reflects the larger volume of tissue, improved calcification retrieval, and lower frequency of histologic underestimates with the vacuum-assisted device [16,17,18,19].
Incomplete follow-up is a limitation of our study. The cost-effectiveness of stereotactic 11-gauge directional vacuum-assisted biopsy depends on the false-negative rate of the procedure. Follow-up studies of stereotactic 14-gauge automated large core biopsy report an average false-negative rate of 2.8% (range, 0.6-8.2%) [33, 34]; approximately 75% of these "misses" are identified immediately after biopsy and 25% subsequently [35]. Although the false-negative rate of stereotactic 14-gauge automated core biopsy is comparable to the average cancer miss rate of 2% (range, 0-8%) reported in studies of needle localization and surgical biopsy [35], the potential exists for a delayed diagnosis of breast cancer [36]. A final analysis of cost-effectiveness of stereotactic 11-gauge directional vacuum-assisted biopsy cannot be complete without long-term follow-up, including determination of the false-negative rate. Our study also does not address the cost-effectiveness of other core biopsy methods such as stereotactic 14- or 8-gauge directional vacuum-assisted biopsy or directional vacuum-assisted biopsy under sonographic guidance.
We estimate that approximately 1 million breast biopsies will be performed in the United States this year, of which at least 300,000 will be for nonpalpable lesions (approximately half calcification lesions and half masses) [8]. Our experience suggests that approximately one third (50,000) of the 150,000 nonpalpable masses will not be amenable to 14-gauge automated core biopsy because of small size, superficial location, or inadequate breast thickness. If our results could be generalized to the national level, selective application of stereotactic 11-gauge directional vacuum-assisted biopsy to calcification lesions (150,000) and masses not amenable to 14-gauge automated core biopsy (50,000) would result in annual national savings of 200,000 times $264, or $52,800,000. The savings of stereotactic 11-gauge directional vacuum-assisted biopsy are even greater when one considers additional savings compared with surgery, including less time lost from work or other activities, sparing preoperative testing and pre- and postoperative visits, and fewer complications [1, 4, 8]. Furthermore, stereotactic biopsy has lower emotional costs to women who can be spared the scarring, deformity, and anxiety associated with undergoing a more invasive surgical procedure [4, 8].
In conclusion, stereotactic 11-gauge directional vacuum-assisted biopsy obviated a surgical procedure in 76% of lesions in this study, resulting in a 20% decrease in the cost of diagnosis compared with surgical biopsy. Although savings per case are modest, 11-gauge directional vacuum-assisted biopsy expands the spectrum of lesions amenable to stereotactic biopsy, potentially increasing cost savings in the population. Selective use of stereotactic 11-gauge directional vacuum-assisted biopsy primarily for calcification lesions and masses that are small, superficial, or in thin breasts could result in annual national savings exceeding $50 million. Further work is necessary to evaluate the use of stereotactic 11-gauge directional vacuum-assisted biopsy in other situations (such as when removal of a larger volume of tissue is desirable), to assess the cost-effectiveness of other biopsy techniques, and to optimize the choice of biopsy method for different lesions. Stereotactic 11-gauge directional vacuum-assisted biopsy allows more women to enjoy the benefits of minimally invasive diagnosis, and does so at a reduction in cost.
Acknowledgments
We thank Benson Dutton for insightful interpretation of Medicare data, D.
David Dershaw for critical review of the manuscript, and David C. Perlman for
invaluable assistance.
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