Abstract P5-16-15: Lymph-vascular invasion in the absence of stomal invasion after neoadjuvant therapy: A rare pattern of residual carcinoma that lacks an AJCC/UICC T category

Abstract

Background: Response to neoadjuvant chemotherapy in breast cancer serves as an important prognostic indicator, as patients whose estrogen receptor (ER) negative and/or HER2 positive cancers undergo a pathologic complete response (pCR) have an excellent outcome. Guidelines on classification of treatment response are available, but data is lacking for the rare event where lymph-vascular invasion (LVI) is the only residual disease in the breast. Only one study (Rabban JT et al, Am J Surg Pathol, 2009) has investigated the significance of this pattern of residual disease. These authors reported 6 patients with residual LVI in the breast in the absence of stromal invasion. Five of the patients also had residual disease in lymph nodes. Prognosis was poor with four of the patients dying in less than 4 years and an additional patient dying at 10 years. The aim of our study was to gather more data on this rare pattern of residual disease, with a focus on node negative cases. Design: We retrospectively identified from our pathology database all cases in which LVI was the only residual disease in the breast after neoadjuvant therapy. Results: A total of 16 cases were identified, yielding an incidence of 1.6% of all cancers undergoing neoadjuvant chemotherapy over a 10 year period. All patients were females with a mean age of 54 years (range 40-69 years). Eight cancers initially presented as a palpable breast mass, 4 as vague breast symptoms, 2 as inflammatory carcinoma and 1 was detected on screening mammogram. In twelve cases the axillary lymph nodes were either suspicious by imaging or proven positive by needle biopsy. The mean pre-neoadjuvant tumor size was 2.7cm (range 0.5-8.0cm). Six cancers were negative for hormone receptors and HER2, eight cancers were positive for HER2 and 4 cancers were positive for ER. After neoadjuvant chemotherapy, nine patients had no residual disease in lymph nodes. The remaining seven patients had residual disease in lymph nodes, although minimal in the majority. The mean follow-up was 65 months for the node negative group (range 9-125 months) and 44 months for the node positive group (range 7-102 months). One death occurred in each group (at 12 months and 67 months respectively), two patients are alive with metastatic disease in the node negative group and the remaining 12 patients are alive without disease. Conclusions: Pure residual LVI after neoadjuvant chemotherapy is a rare event. Our findings show that the outcome associated with residual LVI, with or without residual cancer in nodes, might not be as dismal as previously reported, although longer follow-up will be required. The more favorable outcome observed is in contrast to the single study previously published. Although the difference may be due to details in the type of chemotherapy or stage at presentation, it is difficult to compare the 2 groups of patients due to limited information about the earlier cases. More data is needed to draw conclusions on the prognostic significance of this type of residual disease. The lack of a current AJCC/UICC T category for this finding will make identification of these patients difficult in large databases. Citation Format: Guilbert M-C, Lester SC. Lymph-vascular invasion in the absence of stomal invasion after neoadjuvant therapy: A rare pattern of residual carcinoma that lacks an AJCC/UICC T category [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-16-15.