Ki-67 Assessment Data in Breast Carcinoma: Core Needle Biopsy vs. Resection Specimens (2020–2025, Medica Ruse University Hospital, Bulgaria)

This dataset contains fully anonymized clinicopathological data from 63 cases of breast carcinoma diagnosed between 2020 and 2025 at Medica Ruse University Hospital, Ruse, Bulgaria.

For each case, both core needle biopsy (CNB) and resection specimens were available, and the Ki-67 proliferation index was independently assessed by two pathologists. Along with Ki-67 indices, the dataset includes patient sex, age at diagnosis, TNM stage, and detailed tumor characteristics such as histological type, molecular subtype, receptor status, focality, grade, size, presence/absence of necrosis, stromal elastosis, and desmoplastic reaction.

Abbreviations:

M = Rater 1

D = Rater 2

C = Core needle biopsy

R = Resection specimen

CM = Ki-67 index on core needle biopsy assessed by Rater 1

CD = Ki-67 index on core needle biopsy assessed by Rater 2

RM = Ki-67 index on resection specimen assessed by Rater 1

RD = Ki-67 index on resection specimen assessed by Rater 2

NST = Invasive breast carcinoma of no special type

ILC = Invasive lobular carcinoma

ER = Estrogen receptor

PR = Progesterone receptor

HER2 = Human epidermal growth factor receptor 2

Exclusion criteria:
Cases that had received neoadjuvant therapy or showed noticeable morphological heterogeneity, including intertumoral heterogeneity in multifocal tumors, were excluded from this dataset.

Purpose and use:
The dataset supports research on interobserver variability in Ki-67 scoring and the comparison of Ki-67 indices between CNB and resection specimens.

Anonymization statement:
All patient information has been removed in compliance with GDPR, HIPAA, and Elsevier’s patient consent policy. No identifying details are included.