Measuring Invasive Breast Carcinoma on Core Biopsy-Is It Necessary?

Abstract

Pathologic tumor size is significant in the treatment of breast carcinoma and is routinely measured on excision. To analyze the need for measuring size of invasive mammary carcinoma on biopsy. Nine hundred twenty-two cases of invasive carcinoma whose size was measured (greatest linear measurement) on biopsy and excision was correlated, including imaging when available (110 cases). Patient mean age was 62 years. Most (90%; 830 of 922) carcinomas were ductal and sampled by ultrasound and graded as follows: well, 13% (113 of 922); moderately, 58% (532 of 922), and poorly differentiated, 28% (258 of 922); 19 microinvasive not graded. Tumor mean size was 7.5 mm on biopsy and 14.4 mm on excision. Biopsy modality was as follows: ultrasound, 7.8 mm (92%, 844 of 922); mammotome, 3.3 mm (7%, 65 of 922); and magnetic resonance imaging, 5.9 mm (1%, 13 of 922). Size comparison on biopsy versus excision was biopsy > excision: 8% (72 of 922), biopsy = excision: 10% (95 of 922), and biopsy < excision: 82% (755 of 922). Half (36 of 72) of the biopsy > excision tumors were less than 5 mm, 96% (726 of 755) of biopsy < excision tumors were greater than 5 mm, while those equal on both were predominantly (88%, 84 of 95) less than 10 mm, 20% (19 of 95) of which were microinvasive. Stage changed in 600 cases, staging based on excision in 581 (63%), and staging based on biopsy in 19 (2%). Radiologic-pathologic correlation (n = 110) showed perfect concordance in 11 (10%), 83 (75%) were ±1 to 2 mm, and 16 (15%) were ± more than 3 mm. Difference between the biopsy and excision ranged from a lower limit of 1.3 mm for T1a tumors to 18 mm for T2. While most carcinomas are larger on excision, 18% (167 of 922) are larger or equal on biopsy. Factors predictive of biopsy > excision tumors include stage 1 tumors (P < .001), especially less than 5 mm, and sampled by mammotome. We recommend measuring invasive carcinoma on biopsy and excision.