Fine-needle versus core-needle biopsy – which one to choose in preoperative assessment of focal lesions in the breasts? Literature review

Preoperative verification of focal lesions in the breasts is crucial for further therapeutic decisions. Three most common techniques include: fine-needle aspiration biopsy (FNAB), core-needle biopsy (CNB) and vacuum-assisted biopsy (VAB).

Fine-needle aspiration biopsy was first used in 1930 in New York by Hayes Martin and Edward Ellis. Unfortunately, this method was not popular for the next 25 years. It started to be commonly used in the diagnostic process of palpable breast masses in the 1950s in the Scandinavian Karolinska Institute. FNAB was first used in Poland in the mid-1970s in Szczecin on the initiative of Professor Stanisław Woyke.

Core-needle biopsy was introduced in the 1990s, initially only for clinically silent lesions. However, it rapidly began replacing fine-needle biopsy^(1,2). This method owes its growing popularity not only to its accuracy in the diagnosis of benign lesions, but mostly to its capability of distinguishing between in situ lesions and invasive carcinoma⁽³⁾.

Unquestionable advantages of FNAB include: ready availability, simplicity of the technique, low cost and, most of all, low risk of complications. It requires no anesthesia, is minimally-invasive and relatively patient-friendly (associated with little discomfort). Also, it is the most suitable for patients receiving anticoagulant therapy since it does not require its discontinuation. Moreover, the biopsy result is available several days after specimen collection.

Core-needle biopsy is an invasive procedure conducted under local anesthesia and with image guidance (US, MMG, MRI). The equipment needed includes a biopsy instrument and a needle with a large diameter⁽⁴⁾. Complications after the procedure include a hematoma (<2%), pain and discomfort⁽⁵⁾. Although these complications are more common than after fine-needle biopsy, the percentage is only slightly higher. In the case of a biopsy of a relatively small lesion, it is possible to remove it completely or break it into pieces, which might make surgical excision and histopathological analysis more difficult. In such cases, it is recommended that a tracer should be administered in the region of the lesion to be biopsied.

A lot of authors have compared the sensitivity, specificity and other aspects of FNAB and CNB. Such an assessment is frequently problematic due to differences regarding employed methods, experience in performing biopsy and cytological interpretation.

In a meta-analysis based on over 20 publications, the authors demonstrated varying sensitivity of FNAB that ranged from 35% to 95% and was generally lower than that of CNB (85–100%). Similar results concerned specificity (FNAB 48–100%, CNB 86–100%)⁽⁶⁾. These data indirectly show that results of CNB are more reproducible.

Hukkinen et al. compared the usefulness of both methods in preoperative diagnosis of focal breast lesions. The values for accurate and reliable diagnosis of malignant lesions were 96% for CNB and 67% for FNAB (p=0.001) while the respective values for malignant and suspicious lesions were 99% and 95%. As many as 27% of FNAB results (79/289) were assessed as suspicious and required further histopathological verification⁽⁷⁾.

In 1996, Ballo et al. presented different results that indicated the superiority of FNAB over CNB⁽³⁾. Based on a group of 124 patients with palpable masses and suspicious lesions in mammography, the sensitivity of FNAB was higher than that of CNB: 97.5% vs 90% (p = 0.004)⁽⁸⁾. It must be underlined that FNAB was performed with 23–25 G needles and that as many as 6 aspirates were taken, while CNB was performed thrice with 18 G needles.

He et al. also demonstrated the usefulness of fine-needle biopsy. Their study involved an analysis of 1238 smears collected from painful and inflamed regions and palpable tumors measuring 10–140 mm. From each patient, 2–3 aspirates were taken using 21 G needles under US guidance or 5 aspirates if biopsy was conducted without radiological guidance. The sensitivity of FNAB was 98%, specificity was 99% and false negative rate was 2.3%. These results are unique amongst similar studies. This might have been caused by patient selection based on criteria assumed by the authors, which is confirmed by a considerable percentage of carcinomas amongst tested lesions (1071/1238)⁽⁹⁾. Aker et al., in turn, showed that FNAB and CNB are equivalent, particularly in terms of suspicious lesions⁽¹⁰⁾.

Studies on the relationship between the sensitivity of the method and the number of specimens have confirmed their positive correlation. Fishman et al. observed that cells which enabled the final diagnosis were found in the third sample in 96% of cases⁽⁴⁾. Bolívar et al. analyzed the percentage of normal results in relation to the number of analyzed samples (from 1 to 4): for one sample, it was 73.5%, for two: 88%, for three: 95% and for four: 97.5%⁽¹¹⁾. According to the current recommendations, at least 3 samples should be collected from a focal lesion and at least 5 samples should be obtained from a lesion with microcalcifications.

The false negative rate for CNB reaches 9.9%⁽¹²⁾. Lower sensitivity is linked with the presence of non-diagnostic specimens resulting from difficulties in obtaining the material (sampling error), heterogeneous structure of carcinomas and, more rarely, from an erroneous histopathological assessment (a diagnostic error).

Manual difficulties are associated with a small size of a lesion, deep location, stiffness or movability in relation to the surrounding soft tissues. Technical difficulties, in turn, may be associated with wrong needle bend, problems with visualizing a needle tip and imaging artifacts, e.g. slice-thickness artifact⁽¹³⁾. Owing to the heterogeneous structure of cancer, specimens might contain fat necrosis, desmoplasia or inflammatory cells which can occur between cancer cells. Moreover, slight cancerous lesions in a benign tumor or areas of microinvasion in carcinoma in situ might be indistinguishable from the remaining part of the lesion and draw no attention of a doctor conducting the procedure.

CNB delivers information about the features of cancer, which has therapeutic implications. These features include: presence of invasion, histological type and tumor grade, presence of estrogen receptors (ER) and progesterone receptors (PR), HER-2 status and Ki-67 proliferative index. The sensitivity of receptor and marker assessment is 96% for ER, 90% for PR and 87% for HER-2⁽¹⁴⁾.

Despite many advantages of FNAB mentioned previously, this method has also numerous limitations. First, the invasion status cannot be determined if cancer cells are found. ER, PR and HER-2 status assessment is poorly sensitive and relatively expensive. Moreover, this method is characterized by lower sensitivity and specificity as well as a higher rate of non-diagnostic results, particularly in non-palpable lesions; it might be as low as 34–57%^(15,16). The quality of the diagnostic workup using FNAB largely depends on competence, skill and experience of the operator and cytopathologist⁽¹⁷⁾. Therefore, the sensitivity of FNAB can be increased and the number of non-diagnostic results can be decreased by: proper patient selection, experience of physicians who perform or assess biopsy as well as accuracy and carefulness during sampling and preparing smears.

Histopathological and cytological assessment of focal lesions is of key significance. However, its results must be confronted with imaging findings and clinical data (a triple test)⁽¹⁸⁾. In the case of discrepancies between imaging findings and biopsy results, surgical resection of the lesion is recommended. This management helps avoid false negative results.

Vacuum-assisted biopsy, which was introduced in the 1990s, is used for removal of clusters of suspicious microcalcifications under mammographic guidance. Soon after its introduction, it started to be used in the diagnostic workup of lesions under US or MRI guidance. As with CNB, it is performed with needles of various gauges⁽¹⁹⁾, but it helps obtain a greater amount of tissue from a single slight incision (e.g. 14 G VAB delivers 40 mg of tissue, whereas CNB delivers only 17 mg)⁽¹⁹⁾.

Numerous studies have revealed a lower number of false negative results for VAB than for CNB⁽²⁰⁾ as well as its higher sensitivity and specificity when diagnosing ADH-type lesions (ADH – atypical ductal hyperplasia) and DCIS (ductal carcinoma in situ)^(21,22). This results from a greater amount of tissue obtained with this method. Lower costs, reduced patient burden and slight scars associated with healing make VAB seem more beneficial than surgical biopsy. Lesions that do not exceed 3 cm can be removed fully during vacuum-assisted biopsy using an 8 G needle⁽²³⁾. As for cancerous lesions, however, VAB is not equivalent to surgical resection after which margins of the resected tissue undergo careful assessment. That is why surgery is unavoidable in this case⁽²⁴⁾. The situation when the tissue breaks into pieces during sampling is unfavorable from the histopathological point of view as it might prevent reliable assessment. VAB is characterized by greater cost compared to CNB (it is 10–15 times more expensive than CNB)⁽²⁵⁾.

At present, FNAB is considered a diagnostic method for cystic lesions and lesions suspected of lymph node metastases. It can also be conducted for lesions located near the chest wall (concerns about patient’s movement and the risk of causing pneumothorax), superficial palpable lesions and in order to rule out local recurrence within the chest wall⁽⁵⁾. The diagnostic workup for solid tumors (including atypical, papillary, lobular and fibrous lesions, such as radial scar) with this method is a challenge.

Despite the limitations in the histopathological assessment of CNB specimens, this technique helps establish a correct preoperative diagnosis much more frequently than FNAB (78% vs 55%)⁽²⁶⁾. CNB is performed for BIRADS 4 and 5 focal lesions. It is characterized by a very high negative predictive value, reaching even 99.4%⁽¹³⁾.

The indications for vacuum-assisted biopsy can be divided into diagnostic and therapeutic ones⁽²⁵⁾. VAB is recommended for slight lesions (<5 mm), clusters of suspicious microcalcifications and for verification of non-diagnostic results of other biopsy methods. Therapeutic indications include: removal of BIRADS 3 and 4a lesions (low risk of malignancy, e.g. fibroadenoma, intraductal papilloma) and benign lesions causing troublesome symptoms (pain, discomfort etc.) or anxiety, and if the patient wishes to have them removed.

Hukkinen et al. proved that despite a low cost of FNAB, the need to frequently conduct additional examinations (including CNB) due to non-diagnostic results makes the total cost of fine-needle biopsy exceed that of CNB⁽⁷⁾. The authors estimated the cost of FNAB at EUR 150, and CNB at EUR 176. However, when the cost of additional examinations was added, FNAB cost EUR 294, and CNB: EUR 233. The diagnosis with CNB is therefore 24% cheaper than that with FNAB.

Similar conclusions were drawn by Gruber et al. who compared the cost of ultrasound-guided CNB with surgical resection⁽⁵⁴⁾. Biopsy lowered the cost by 30% compared to tumorectomy. Moreover, as many as 60% of women were not operated on after considering the result of CNB.

One must not forget that additional procedures prolong the time from the first visit to final diagnosis, which delays treatment.

Although there is histological evidence for the movement of cancer cells from the site of the primary lesion to the biopsy route, it has been proven that these cells do not survive in the new location. Moreover, there is no evidence to support the fact that preoperative breast biopsy might cause cancer cell movement to sentinel lymph nodes⁽⁵⁵⁾.

Cytological and histological verification of breast lesions is crucial for treatment planning. When selecting a diagnostic method, one should consider a range of factors to choose either CNB or FNAB. A multidisciplinary approach, i.e. cooperation between oncologists, radiologists and pathologists, has a positive influence on the quality of both diagnosis and treatment. Currently, core-needle biopsy is the method of choice in the diagnosis of focal breast lesions. Fine-needle biopsy is used in the diagnostic workup of cystic lesions and suspicious axillary lymph nodes in patients with breast tumors.