Abstract P2-05-31: High-risk breast cancer is less likely to occur in the ductal hyperplasia lesions or low-grade DCIS ∼ Consideration of long-term follow-up observation after surgical biopsy

Abstract

Abstract <Introduction> Even if many ductal hyperplasia lesions and low grade DCIS are detected by breast cancer screening using high-resolution imaging modalities, we have often experienced high-grade breast cancer as an interval cancer. We might consider whether the detection of ductal hyperplasia lesions and low grade DCIS in breast cancer screening really leads to a decrease in breast cancer death. Therefore, we examined the follow-up periods after the removal of lesions. And we would like to refer to the problem of over-diagnosis and over-treatment of LGDCIS. <Subjects and Methods> At our facility from 1997 to 2012, we examined 354 cases of ductal hyperplasia lesions which were treated with surgical biopsy and followed up with observations spanning at least three years. The ductal hyperplasia lesions shown here are the usual ductal hyperplasia, flat epithelial atypia, atypical ductal hyperplasia, and intraductal papilloma. The median of the follow-up observation period was 73 months. In addition, we had 153 cases of low-grade DCIS patients who underwent follow-up of more than three years without postoperative irradiation. The median of the follow-up period was 63 months. <Result> (1) In ductal hyperplasia lesions, 25 cancers occurred in both breasts. There were 13 cases of DCIS in the histopathological examination (52%) and 12 cases of invasive cancer (46%). In DCIS, low-grade DCIS of Van Nuys1 accounted for 86%. Luminal A was 75% in invasive cancer. Lymph node metastasis was observed in only two cases, with one case having one metastatic lymph node and the other having two. Her2 type and triple-negative type accounted for one case each. Her2 type was microinvasive carcinoma, and Ki67 was 22% in triple negative type. The potential for malignancy in both was not so high. In low-grade DCIS (non-irradiated), 11 cancers occurred in both breasts. There were 8 cases of DCIS (73%) and three cases of invasive cancer (27%). All of the DCIS cases were VanNuys1. All of the invasive cancer cases were luminal A. (2) We compared the cancer occurrence in benign lesions and low-grade DCIS (surgery side). The occurrence rate was 2.2% for benign lesions and 3.2% for low-grade DCIS over a five-year period. There was no significant difference found between the two groups. <Conclusion> High-risk breast cancer is less likely to occur in ductal hyperplasia lesions or low-grade DCIS. In other words, terminal duct lobular unit (TDLU) in both breast who had been affected with ductal hyperplasia or low grade DCIS lost a risk of the occurrence of high grade malignant cancer. Therefore, women with ductal hyperplasia and LGDCIS should be placed in the low-risk group of future breast cancer deaths. Small low grade DCIS might be regarded to be nearly as innocent as benign hyperplastic lesions. Citation Format: Takebe K, Arai T. High-risk breast cancer is less likely to occur in the ductal hyperplasia lesions or low-grade DCIS ∼ Consideration of long-term follow-up observation after surgical biopsy [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 P2-05-31.