When breast cancer is diagnosed, evaluation of the lymph nodes of the armpit, called “axillary lymph nodes” is performed during clinical examination as part of the staging of the breast cancer. When abnormal lymph nodes are felt, this is usually followed by an ultrasound of the armpit to evaluate the lymph nodes further. This is called axillary ultrasound. Abnormal looking lymph nodes are then sampled to obtain tissue from which the pathologist can determine whether the lymph node contains tumor cells.
There have been two methods of sampling these axillary lymph nodes. The earlier method called fine needle aspiration involved inserting a needle mounted on a syringe and suctioning some of the cells into the syringe for further evaluation under a microscope. A subsequent method, called core needle biopsy involved inserting a much larger hollow core needle and taking out a cylindrical piece of tissue for further evaluation under the microscope by the breast pathologist.
A new study, called meta-analysis, tabulated the results of six prior studies evaluating the outcomes of sampling axillary lymph nodes using fine needle aspiration versus core needle biopsy. This study was just published in the British Journal of Surgery. This type of Meta-analysis study can sometimes answer questions that a single study cannot. By combining the data from all previously published relevant studies, the meta-analysis achieves strength in numbers and can prove or disprove hypotheses that the earlier studies could not do on their own because they suffered from inadequate statistical power due to the smaller numbers of patients who were part of the study.
This meta-analysis study showed that Ultrasound-guided core needle biopsy was superior to fine needle aspiration in terms of sensitivity, meaning the ability of the test to detect abnormal cells. Ultrasound-guided core needle biopsy was also associated with a lower need for repeat biopsy. However, the complication rates were slightly higher for ultrasound guided core needle biopsy than for fine needle aspiration. The better results shown by core needle biopsy stem from the fact that this approach obtains a larger amount of tissue than fine needle aspiration. The authors conclude that ultrasound-guided core needle biopsy is the preferred choice for evaluating abnormal looking lymph nodes in the armpit during workup of breast cancer.