I. UNDERESTIMATION RATE
- All 60 patients were women (age range, 24–88 years; mean age, 47.5 ± 11.3 years). Of the 69 DCIS lesions diagnosed after a US-14G-CNB, invasive carcinoma was diagnosed in 21 lesions in 19 patients following surgical excision (underestimated group).
- Thus, the rate of underestimation of DCIS in this study was 30.4% (95% confidence interval, 17.4%–38.0%).
II. COMPARISONS OF THE UNDERESTIMATED AND NON-UNDERESTIMATED GROUPS
Table 1. Comparisons of clinical findings in the underestimated and non- underestimated groups
Clinical findings | Underestimated n = 21(%) | Non-underestimated n = 48(%) | p-value |
Age (mean ± standard deviation) | 50.7 ± 11.6 | 46.1 ± 11.0 | 0.986 |
Symptom | 10 (47.6) | 36 (75) | 0.129 |
Palpability | 10 (47.6) | 21 (43.8) | |
Localized pain | 0 (0) | 7 (14.6) | |
Nipple discharge | 0 (0) | 8 (16.7) | |
Asymptomatic | 11 (52.4) | 12 (25.0) | |
Table 2. Comparisons of mammographic findings in the underestimated and non- underestimated groups
| Underestimated n = 21(%) | Non- underestimated n = 48(%) | p-value |
Mammographic finding | | | 0.974 |
Negative | 3 (14.3) | 6 (12.5) | |
Calcification only | 7 (33.3) | 19 (39.6) | |
Mass | 2 (9.5) | 3 (6.3) | |
Mass with calcifications | 4 (19) | 9 (18.8) | |
Asymmetry | 4 (19) | 7 (14.6) | |
Asymmetry with microcalcifications | 1 (4.8) | 4 (8.3) | |
Table 3. Comparisons of sonographic findings in the underestimated and non- underestimated groups
| Underestimated n1 = 21(%) | Non-underestimated n = 48(%) | p-value |
Size (mean ± standard deviation) | 2.3 ± 1.1 cm | 1.6 ± 0.8 cm | 0.151 |
Sonographic findings | | | |
Shape | | | 0.210 |
Oval | 4 (19) | 19 (39.6) | |
Round | 2 (9.5) | 2 (4.2) | |
Irregular | 15 (71.4) | 27 (56.3) | |
Orientation | | | 0.276 |
Parallel | 11 (52.4) | 33 (68.8) | |
Non-parallel | 10 (47.7) | 15 (31.3) | |
Margin | | | 0.103 |
Circumscribed | 0 (0) | 2 (4.2) | |
Indistinct | 4 (19) | 16 (33.3) | |
Angular | 0 (0) | 0 (0) | |
Microlobulated | 13 (61.9) | 29 (60.4) | |
Spiculated | 4 (19) | 1 (2.1) | |
Boundary | | | 0.233 |
Abrupt | 3 (14.3) | 14 (29.2) | |
Echogenic halo | 18 (19.1) | 34 (70.8) | |
Echogenicity | | | 0.365 |
Hyperechoic | 0 (0) | 0 (0) | |
Isoechoic | 3 (14.3) | 4 (8.3) | |
Hypoechoic | 16 (76.2) | 41 (85.4) | |
Mixed echogenicity | 2 (9.5) | 3 (6.3) | |
Microcalcification within the mass on US | 11 (52.4) | 28 (58.3) | 0.793 |
Final assessment | | | 0.148 |
4 | 12(57.1) | 37(77.1) | |
5 | 9(42.9) | 11(22.9) | |
Abnormal lymph node in the axilla on US | 5/19(26.3) | 2/41(4.9) | 0.016 |
1Number of lesions
- Two patients in the non-underestimated group (2/41 patients [4.9%]) and 5 patients in the underestimated group (5/19 patients [26.3%]) demonstrated the presence of abnormal axillary lymph nodes on US with a statistically significant difference (p = 0.016). However, there were no statistically significant differences between the underestimated and non-underestimated groups with respect to the mammographic findings, sonographic findings, size, age, and clinical symptoms, except for the presence of abnormal axillary lymph nodes depicted on US.(Figs: case 1 and case 2)
Case 1. The underestimated group
Fig.: Case 1(a). Imaging findings are presented for a 42-year-old woman with invasive ductal carcinoma. Mammography demonstrates suspicious microcalcifications in the right breast(a).
Fig.: Case 1(b). Imaging findings are presented for a 42-year-old woman with invasive ductal carcinoma. Breast ultrasound reveals a 3 cm, irregularly-shaped and microlobulated margined hypoechoic mass with echogenic foci within the right upper outer quadrant (b).
Fig.: Case 1(c). Imaging findings are presented for a 42-year-old woman with invasive ductal carcinoma. Abnormal lymph nodes without fatty hilum in the right axilla are present (c). The patient underwent an ultrasound-guided 14-gauge core needle biopsy with a ductal carcinoma in situ identified based on the subsequent histology. However, invasive carcinoma was found following surgical excision with the presence of metastatic lymph nodes detected after axillary lymph node dissection.
Case 2. The non-underestimated group
Fig.: Case 2(a). Imaging findings are presented for a 42-year-old woman with ductal carcinoma in situ. Ultrasound demonstrates an irregularly-shaped, hypoechoic mass in the right upper outer portion (a) with a normal appearing lymph node (arrows) in the right axilla (b). The pathologic findings following an ultrasound-guided 14-gauge core needle biopsy and surgical excision was consistent with ductal carcinoma in situ.
Fig.: Case 2(b). Imaging findings are presented for a 42-year-old woman with ductal carcinoma in situ. Ultrasound demonstrates an irregularly-shaped, hypoechoic mass in the right upper outer portion (a) with a normal appearing lymph node (arrows) in the right axilla (b). The pathologic findings following an ultrasound-guided 14-gauge core needle biopsy and surgical excision was consistent with ductal carcinoma in situ.
III. RESULTS OF AXILLARY LYMPH NODES
- An axillary lymph node dissection or a sentinel lymph node biopsy was performed in 58 of 60 patients. In all 41 patients in the non-underestimated group, no axillary lymph node metastases were detected, whereas metastatic axillary lymph nodes in 3 of 17 patients were present in the underestimated group after surgery. This difference was statistically significant (p = 0.02 by Fisher’s exact test).
- Among the seven patients determined to have abnormal axillary lymph nodes on US, two patients in the underestimated group were shown to have lymph node metastasis following surgery.
- The sensitivity and positive predictive value (PPV) of the axillary US findings with the histopathologic correlation of lymph node metastasis in the study were 66.7% (2/3) and 28.6% (2/7), respectively.
IV. COMPARISONS OF PREVIOUSLY REPORTED DATAS
- Variable DCIS underestimation rates ranging from 5%-44% have been reported and most biopsies have been performed using stereotactic devices with directional vacuum-assisted biopsy in addition to automated large-core needle biopsy. However, US-14G-CNB rates of underestimating DCIS have not been evaluated as compared to the use of a stereotactic biopsy.
- We identified the rates of DCIS underestimation after a US-guided-CNB that ranged from 20%-66.7% in 10 studies in the literature review (Table 4) and the original aim of these studies was to evaluate the accuracy of a US-guided-CNB and not to determine rates of DCIS underestimation
Table 4. Reported ductal carcinoma in situ underestimation rates after an ultrasound-guided 14-gauge core needle biopsy
Study | Target | Core needle size | DCIS for CNB/Total number of biopsied cases | Total number underestimated |
Smith et al., 2001 3 | Sonographically visible mass subtracting calcifications only | 14- ACN | 5/128(1%) | 1/5(20%) |
Schoonjans et al., 2001 24 | Palpable and non-palpable sonographically visible breast masses | 14- ACN | 9/424(2.1%) | 5/9(55.5%) |
Buchberger et al., 2002 23 | Breast masses and calcifications | 14- ACN | 10/590(1.7%) | 3/10(30%) |
Philpotts et al., 2003 25 | Sonographically visible breast lesions (primarily breast masses) | 14- ACN | 2/181(1.1%) | 1/2(50%) |
Pijnappel et al., 2004 26 | Breast mass and calcifications only | 14 or 18 ACN | 8/128 (6.3%) | 5/8(62.5%) |
Crystal et al., 2005 27 | Sonographically visible breast masses | 14- ACN | 6/715(0.8%) | 4/6(66.7%) |
Sauer et al., 2005 28 | Palpable or non-palpable, sonographically visible breast masses | 14- ACN | 19/962(2.0%) | 11/19(57.9%) |
Cho et al., 2005 29 | Sonographically visible breast mass (n=551) and calcifications (n=11) | 14- ACN | 10/562(1.8%) | 5/10(50%) |
Youk et al., 2008 5 | Sonographically visible breast masses (palpable or non-palpable) subtracting calcifications only | 14- ACN | 126/2420(5.2%) | 36/126(29%) |
Schueller et al., 2008 30 | Sonographically visible, non-palpable breast masses | 14- ACN | 52/1061(4.9%) | 19/52(36.5%) |
Current study, 2009 | Sonographically visible breast mass (palpable or non-palpable) subtracting calcifications only | 14- ACN | 69/3124 (2.2%) | 21/69 (30.4%) |
ACN: automated core needle, DCIS: ductal carcinoma in situ, CNB: core needle biopsy
- Higher rates of DCIS underestimation determined with the use of US guidance as compared with stereotactic biopsy techniques may be explained as most US-guided biopsy procedures are performed on a mass and the underestimation of invasive cancer is more frequent for a mass than for a microcalcification. Some investigators have reported that 90% of carcinomas that present as microcalcifications alone were non-infiltrating, whereas 84% of carcinomas that present as a mass were invasive.
- In the present study, the rate of DCIS underestimation was 30.4% (21 of 69 lesions), which is within the range of previously published results.