Use of Core Needle Biopsy rather than Fine-Needle Aspiration Cytology in the Diagnostic Approach of Breast Cancer

Diagnosis of breast cancer is carried out by three medical members, the surgeon, who covers breast examination, the radiologist for mammography and ultrasound, and the pathologist for fine-needle aspiration cytology (FNAC) and core needle biopsy (CNB). Fine-needle aspiration biopsy (FNAB) has long been the most functional examination to determine the nature of the nodules, but gradually, CNB is being introduced [1,2,3,4]. The difference between the two techniques has been extensively studied, and several publications have highlighted the strengths and weaknesses of each [5,6]. CNB is used when FNAB is unable to give precise results, when there is a discordance between clinical, instrumental examination and cytology, or when it is preferable to obtain a histological examination of the lesion rather than a simple cytological examination (e.g. malignant lesions resulting from neoadjuvant chemotherapy).

CNB is certainly more reliable than cytology and less invasive than surgical biopsy, and allows you to plan therapeutic treatment. On the other hand, we have found it to be more expensive and invasive than cytology, and sometimes it is difficult to pinpoint subareolar injury or areas close to the pectoral muscle. There is also the risk of underestimating lesions in some cases [7,8]. This report covers the results of 4 years of experience with CNB at a center for the study, prevention and therapy of breast cancer.

Over the past few years CNB has been the first approach in cases of large lesions clearly malignant at mammography and/or ultrasound, where the future treatment will be neoadjuvant therapy. A CNB test was added in other cases after FNAB when the result was nondiagnostic or inconclusive. Whenever possible the procedure of FNAC and CNB was carried out a few days after the diagnosis of nodular lesion in order to minimize the patient's state of apprehension.

From 2009 to 2013, 712 breast biopsies were performed on women aged between 24 and 85 years (average age 55 years) visiting our center for screening or symptomatic consultancy. All patients above the age of 40 underwent clinical breast examination, mammography and ultrasound when requested by the radiologist; patients below the age of 40 were subjected to clinical breast examination and ultrasound only.

To ensure a correct classification and evaluation of the results, the diagnostic conclusions of the mammographies were classified into 5 categories, in accordance to both European and American recommendations (table 1). A similar classification was also used for the subsequent ultrasound examination (U) and for the definition of the classes ‘cytological' (C) and ‘histological' (B) in order to facilitate interdisciplinary communication.

All biopsies were performed under ultrasound guidance by experienced radiologists or sonographers dedicated to the prevention of breast cancer in an outpatient setting. Local anesthesia with the addition of adrenaline to reduce bleeding was used, and then a small incision was made to allow the insertion of the biopsy needle. In all cases, we attempted to withdraw 10 frustules, because, as claimed by some authors, increasing the number of biopsies increases the accuracy of the diagnosis, and in Brenner et al.'s case, the accuracy after 5 biopsies was 98% for masses [9,10,11,12]. This method was not always possible due to bleeding, and in the case of patients who were particularly apprehensive, we were unable to complete the procedure.

We used two techniques: vacuum-assisted breast biopsy (VABB) with 8-, 11- or 14-gauge Mammotome probes (Devicor Medical Products, Inc.), or Tru-cut (Bard Magnum, Bard Biopsy Systems) with 12- or 14-gauge, 13-cm probes [13,14,15,16]. VABB was used whenever possible, but with very deep nodules adhering to the pectoral muscle or in the case of patients with very small breasts, Tru-cut was applied. VABB was found to be preferable as we were able to collect contiguous samples with a single introduction of the needle, and the quantity of tissue retrieved was greater. Therefore, the majority of pathologists prefer this technique, and it is much easier to locate the biopsied point.

In 165 cases, a nonmagnetic clip (MammoMARK, Devicor Medical) was placed to locate the lesion in the subsequent follow-up, when the lesion was too small and therefore difficult to find in the event of a subsequent surgery or in patients who are candidates for neoadjuvant therapy in order to more efficiently monitor the effectiveness of the therapy.

According to our experience, the average time to perform the biopsy was 20 min with a peak of 60 min from the beginning. Immediately after the procedure, synthetic ice was positioned upon the biopsy area of the patient for a few hours to prevent any bleeding. In the beginning, we tried to completely remove some injuries. Further on, this idea was abandoned as after the 6-month checkup, many patients were reported to have small residual nodules which had not been detected at the time of procedure.

From December 1, 2009 to December 31, 2013, ultrasound-guided biopsies were performed in 712 women aged between 24 and 85 years (average age 55 years). The biopsied nodules were of variable dimensions ranging from 10 to 50 mm: 29.3% were less than 1 cm in size, 53.6% were between 10 and 19 mm, 14.4% between 20 and 39 mm and only 2.7% of the total tested were larger than 40 mm.

VABB was used whenever possible and Tru-cut in the case of very deep nodules adhering to the pectoral muscle or in case of patients with very small breasts. A total of 556 VABB probes were carried out (496 probes using a caliber of 11 gauge, 47 using 14-gauge probes, and 13 using 8-gauge probes) and 156 Tru-cut (94 probes of 12 gauge, 61 probes of 14 gauge, and 1 probe of 16 gauge, all with a length of 13 cm).

The following number of frustules were sent for histological examination: 4-10 frustules in 238 cases, 11-20 frustules in 327 cases, 21-30 frustules in 142 cases and 31-40 frustules in 5 cases. In 141 patients, more than 10 frustules were taken in an attempt to completely remove the lesion using VABB with an 11- or 8-gauge probe, but complete removal occurred only in 93 cases, while in the remaining 48 cases, after the ultrasound-guided follow-up 6 months later, minimum residue of the lesion was still present [17,18,19,20].

In 165 cases, a nonmagnetic metal clip was placed (MammoMARK, Devicor Medical, characterized by a bioabsorbable collage capsule in integrated titanium wire marker in nonabsorbable radio-opaque compatible with an MRI field of 3.0 tesla or less), useful for the retrieval of examination specimens in the subsequent follow-up.

Breast biopsy under ultrasound guidance is a relatively quick method, being both safe and simple to perform. Complications in our center were minimal: in 91% of cases, no complications were found, in 8.7% of cases, hematoma was present, disappearing within a few days, and in only 0.3%, lymphangitis was diagnosed.

In figures 1, 2 and 3, all positive biopsies were compared with mammography, ultrasound and cytology to assess which method was more reliable in the diagnosis of a malignant disease. Figure 1 shows that in 63% of patients with a diagnosis of mammographic R5, the diagnosis was confirmed by biopsy, in 7% of patients, the breast was too dense to highlight the lesion (R1), and in 31%, mammography detected uncertain lesions with benign prevalence (R3) to be later confirmed after histological sampling [21]. 35% of the lumps that were non-diagnostic or benign at cytological examination (C1, C2) had a positive biopsy, 16% of C3 were neoplastic lesions, in 49% of cases in which cytology identified the nodule as suspicious or a certainty for malignancy (C4, C5), the diagnosis was confirmed by biopsy (fig. 2). Figure 3 shows all the cases with positive histology and the correlation with ultrasound. Among the 11% of the nodules classified as uncertain on ultrasound (U3), 10% were found to be malignant on histological examination. Only in 1% of the cases was the CNB unable to resolve the uncertainty, and the patients were sent to surgery; 89% of those suspected positive to ultrasound (U4-U5) were confirmed at histological examination.

In the diagnostic path of benign and malignant lesions of the breast, there is currently increasing recourse to methods of biopsy of palpable or nonpalpable lesions in order to determine those who will definitely need surgery [22]. When cytological examination is insufficient to provide a diagnosis or is not adapt as in large lesions (generally more than 2 cm) that will undergo neoadjuvant therapy, the chosen method is breast biopsy, generally ultrasound-guided.

Currently, there are essentially two methods used for breast biopsies: VABB and Tru-cut. In our series, we used VABB whenever possible and Tru-cut in the case of very deep nodules adhering to the pectoral muscle or in case of patients with very small breasts. The usage of VABB can extract contiguous samples with a single introduction of the needle, resulting in a lower risk of infection and less discomfort for the patient. In addition, more material is obtained due to the force of aspiration. In both cases, there is the possibility to leave a metal clip in position for the next ‘search unit' lesion.

Over the past years, the use of breast biopsy has been a precise step in diagnostic and therapeutic breast lesions, as a method of second level after cytology failure, or as a method of first level in those lesions with ultrasound characteristics of sure malignancy or larger than 2 cm in size to be subjected to neoadjuvant chemotherapy [23].

Based on our experience on 712 consecutive breast biopsies performed over a range of 4 years, we can say that in many cases, FNAB was not conclusive, and therefore, we proceeded with the echo-guided biopsy, with which enough material was collected for histological examination, enabling us to direct patients to surgery or follow-up. The cost for FNAC was lower in the beginning, but the actual cost to obtain a definitive diagnosis was considerably higher for FNAC as it was less accurate and often backed up by further examinations such as CNB.

In accordance with recent publications, we conclude that, especially at a time when expenditure is constantly reviewed, CNB is far superior to FNAC in the diagnostic approach of breast cancer and, especially in cases of doubt, it is preferable to proceed directly with CNB, which may also determine additional prognostic and predictive markers.

The authors declare that they have no conflict of interest in relation to this paper.