Approximately 500,000 open excisional breast biopsies are performed annually in the United States and, of these, more than 80 percent are found to be benign. Various methods to establish an accurate, efficient and less invasive diagnostic technique have been evaluated including mammography, ultrasonography, core needle biopsy and fine-needle aspiration. The latter technique has become increasingly popular in the diagnostic work-up of a palpable breast mass because it can be performed in the physician's office without anesthesia. It is a sensitive, expedient and economical method of obtaining cytologic material for pathologic examination. O'Neil and colleagues performed a retrospective study to evaluate the accuracy of fine-needle aspiration by comparing the cytologic findings with that of histopathology.

A retrospective review was performed of the medical records of women who had undergone fine-needle aspiration of a palpable breast lesion followed by a histopathologic confirmation of the diagnosis. The procedure for histopathologic confirmation of the diagnosis included an open excisional biopsy, a core-needle biopsy or a mastectomy specimen. Fine-needle aspiration was performed using a 23-gauge needle and a 10-mL syringe attached to an aspiration gun. Two separate passes were made into the breast lesion with the needle. The biopsy specimens were then fixed in alcohol and stained with Papanicolaou stain. On examination, they were assigned one of three diagnoses: malignant, suspicious or benign.

A total of 697 cases fulfilled study criteria. A diagnosis of “malignant” was made for 401 (58 percent) of these specimens. The positive predictive value of a malignant reading was 99 percent. A diagnosis of “suspicious” was made for 125 specimens (18 percent). Of these, 84 (67 percent) were malignant and 41 (33 percent) were benign or “false suspicious.” A total of 166 of the 697 specimens were read as “benign” (24 percent) and, of these, 153 were true-negative benign lesions (92 percent). A small number of these (5 percent) were fibroadenomas; the rest were fibrocystic disease. Thirteen lesions diagnosed as benign were found to be malignant on histopathologic examination. This represented a false-negative rate of 1.9 percent for the entire series. The false-negative specimens tended to be the types of lower-grade and slower-growing tumors that have a better prognosis. These results were thought to be sampling problems and not interpretation errors.

The authors conclude that fine-needle aspiration is a highly sensitive method for evaluating palpable breast masses for malignancy. When a definitive tissue diagnosis can be made, it is highly predictive of the mass being positive or negative for cancer. However, fine-needle aspiration should never be the sole diagnostic modality used to determine treatment interventions.