[137] The Impact of the Greatest Linear Extent of Invasive Mammary Carcinoma in Needle Biopsy Material on Final Pathological Size and Tumor Stage

Henry D Edwards, Omar Hameed. Vanderbilt University Medical Center, Nashville, TN

Background: Pathologic tumor size (TS) is one of the most important prognostic factors in invasive mammary carcinoma (IMC) and is usually determined after definitive excision (Ex). To our knowledge there are no systematic studies that specifically evaluate the impact of TS in needle biopsy (NB) material on the final pathologic TS and pathologic tumor (pT) stage.
Design: Tumor size in NB material, determined by greatest linear extent (GLE), was compared to that on Ex and the relationship between them and with final pT stage was determined for 99 consecutive IMCs. Statistical analysis was also performed to evaluate any associations between clinicopathological features and finding a larger size on NB.
Results: The overall mean TS on NB was less than that of the corresponding resection (0.84 vs. 1.3 cm; P<.0001, paired t-test); however, the opposite was seen when only small tumors (≤5mm) were considered (0.42 vs. 0.26 cm; P=.066). There were 19 cases in which TS on NB was greater than that on Ex, with the differences being statistically significant (Figure 1). Of these 19 cases, 12 resulted in a higher pT stage (Figure 2). A larger TS on NB compared to Ex was significantly associated with a lower final pT stage (P=.007, Χ2) and neoadjuvant therapy prior to resection (P=.01), but not with patient age, histologic type, histologic grade, proliferation rate or the presence/absence of DCIS (P=.19, .53, .7, .83 and .07, respectively).
Conclusions: These findings show that the greatest linear extent on needle biopsy often contributed the largest tumor size and, in a significant proportion of cases, resulted in a higher overall pT than would have been obtained by measurement on the excision alone. Accordingly, it is recommended that greatest linear extent of invasive mammary carcinoma should be reported in needle biopsy material, particularly in the setting of small tumors.

Category: Breast

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 5, Wednesday Afternoon


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