Material and
Methods: A total of 140 tru-cut biopsies with DCIS were included. We evaluated the predominant structural pattern, nuclear grade, presence of comedonecrosis, and ER/HER2 expressions and their relationship with invasion upstage. Based on the results, an invasion risk scoring system was created using OpenAI-ChatGPT 5.2.
Results: Of the 140 cases, 70 (50%) were high-grade (DCIS-3), 49 (35%) were intermediate-grade (DCIS-2), and 21 (15%) were low-grade (DCIS-1). DCIS-1 and DCIS-2 showed significant association with a cribriform pattern, and DCIS-3 showed with a solid pattern. When the results were compared with those of the final specimens, invasion upstaging occurred in 9.5% of DCIS-1, 38.7% of DCIS-2, and 52.8% of DCIS-3 cases. A solid pattern, high nuclear grade, comedonecrosis, and ER-/HER2- profile showed high correlation with invasion. In AI-assisted risk scoring, DCIS cases were divided into three groups: low, medium, and high risk. The invasion upstaging rates in these groups were 11.44%, 28.97%, and 64.19%, respectively.
Conclusion: DCIS with high nuclear grade, comedonecrosis, a solid pattern, and the ER-/HER2+ or ER-/HER2- immunoprofile should be considered high risk for invasion. They should be approached as invasive tumors and evaluated in terms of lymph node staging and neoadjuvant treatment.
A total of 140 patients were included in the study. The initial material obtained from all patients was a tru-cut biopsy. Those with final excisional specimens (mastectomy, lumpectomy, breast conservation, etc.) were prioritised. Patients with non-tru-cut biopsies, no excisional specimens, microinvasion/invasion or suspicion of microinvasion/ invasion on tru-cut biopsy, lymphovascular or perineural invasion, previous breast diagnosis and Paget’s disease of the nipple were excluded from the study. The clinical and demographic data were obtained from the patient records.
Histopathological Evaluation
The histopathological evaluation comprised a re-evaluation of the tru-cut biopsies of DCIS by two pathologists with experience in breast pathology. This entailed an assessment of the predominant growth pattern (solid, cribriform, micropapillary, papillary, flat), the presence or absence of comedonecrosis and nuclear grade, and the final specimens for invasion.
Immunohistochemical Analysis
A total of 140 cases were evaluated for estrogen receptor (ER) (Ventana SP1 clone) and HER2 (clone 4B5; Ventana Medical Systems, Inc.) according to the evaluation criteria specified in the fifth edition of the World Health Organization (WHO) classification of breast tumours [22]. In cases where the HER2 result was deemed to be equivocal, a confirmation test was conducted using the Ventana HER2 Dual in situ hybridization (ISH) DNA probe cocktail, in accordance with the following criteria.
Evaluation criteria;
ER; Staining at any intensity of 1% or more HER2;
3+: Circumferential membrane staining that is complete, intense, and in > 10% of tumor cells 2+: Weak to moderate complete membrane staining observed in > 10% of tumor cells 1+: Incomplete membrane staining that is faint / barely perceptible and in > 10% of tumor cells 0: No staining is observed, or incomplete membrane staining that is faint / barely perceptible and in ≤ 10% of tumor cells DCIS cases in tru-cut specimens were evaluated in four groups as follows: hormone positive (ER+/HER2-), HER2 positive (ER-/HER2+), ER-/HER2-, and ER+/HER2+. This classification system is consistent with the immunoprofile groups of invasive breast carcinoma specified in the fifth edition of the World Health Organization’s Tumours [22].
AI-assisted Invasion Risk Scoring
AI-assisted model construction;
A file containing the raw histopathological and immunohistochemical data for 140 cases, anonymised and individually recorded, was uploaded to the ChatGPT 5.2 database. The AI tool was instructed as follows: ‘The data for 140 cases diagnosed with ductal carcinoma in situ on Tru-cut biopsy are available in the relevant file. By analyzing these data and comparing them with similar studies in the literature, would you create an invasion risk scoring system similar to the Nottingham scoring system used in invasive breast carcinomas?’ The request was made to evaluate ER and HER2 status together, similar to the subtyping used in invasive breast carcinomas.
The following results were obtained from the command:
The construction of a LASSO (least absolute shrinkage and selection operator) logistic regression model, with the assistance of artificial intelligence, was undertaken for the purpose of predicting invasion upstaging.
The following steps were taken in the creation of the model: Automated variable selection was performed. The penalisation of overfitting was maintained. The interpretability of the model was deemed suitable for clinical and pathological applications.
The model incorporated the following variables:
A comprehensive consideration was given to the following factors: the presence of nuclear grade, the presence of a histological DCIS pattern, the ER status, the HER2 status, and the presence of comedonecrosis. The binary outcome variable was invasion upstaging (0 = no invasion, 1 = invasion present).
Model training and prediction;
The model was trained using the entire dataset to estimate regression coefficients and generate an individual predicted probability of invasion for each case. No imputation was performed, as complete data were available for all included variables.
Risk Stratification;
Initially, the variables were assigned individual scores based on their relationship with invasion upstaging (Table I). The cases were stratified into three invasion risk categories based on the AI-derived predicted probabilities. The risk level is categorised as follows: low (total score 3-5), intermediate (total score 6-8), or high (total score 9-11).
Table I: AI-assisted risk scoring of potential invasion
The risk group cutoff values were determined using tertilebased probability thresholds. This approach offers an objective, distribution-driven classification that does not rely on the utilisation of arbitrary thresholds.
Model Performance Evaluation;
The performance of the model was evaluated through the implementation of receiver operating characteristic (ROC) curve analysis. The area under the curve (AUC) was calculated as a measure of discriminative performance. The area under the curve (AUC) value was calculated as 0.88 by artificial intelligence, and this value was considered to be quite strong for the distinction between invasive and noninvasive cases.
Statistical Analysis
Machine learning procedures were performed using Python-based analytical tools. The descriptive statistics of the data obtained from the study will be presented for numerical variables, including the mean, standard deviation, frequency, and percentage analysis for categorical variables.
The conformity of numerical variables to a normal distribution will be examined using the Shapiro-Wilk test. The independent samples t-test/Mann-Whitney U-test will be employed for the comparison of numerical variables according to categorical variables, including two groups. The Analysis of Variance/Kruskal-Wallis test will be used for the comparison of numerical variables according to three or more categorical variables. Moreover, differences between categorical variables will be evaluated through a Chi-square analysis. Furthermore, the relationships between numerical variables will be examined through the use of Pearson correlation analysis or Spearman correlation analysis. The analyses will be conducted using the SPSS 22.0 software.
The level of significance will be set at p < 0.05.
Comedonecrosis was identified in a total of 54 DCIS cases, with a prevalence of 4.7% in the DCIS-1 group, 8.1% in the DCIS-2 group, and 70% in the DCIS-3 group. The presence of comedonecrosis was found to be significantly associated with high nuclear grade and the solid pattern (p < 0.05). Upon immunohistochemical evaluation, 20 of the 21 cases in the DCIS-1 group were identified as ER+/HER2-, while one case exhibited ER-/HER2+ status. Of the 49 cases in the DCIS-2 group, 36 exhibited an ER+/HER2- immune profile, 7 demonstrated a ER-/HER2+ profile, and 6 displayed an ER-/HER2- profile. In the DCIS-3 group, 19 of the 70 patients were ER+/HER2-, 38 were ER-/HER2+, 2 were ER+/HER2+, and 11 were ER-/HER2-. The DCIS-1 and DCIS-2 groups exhibited a significant hormone-positive immune profile, while the DCIS-3 group demonstrated a significant ER-/HER2+ immune profile (p < 0.05). The ER-/HER2- cases were observed in the DCIS-2 and DCIS-3 groups, while the ER+/HER2+ cases were observed in the DCIS-3 group. However, no significant differences were identified between the groups. A summary of the histopathologic and immunohistochemical data for all three groups is provided (Table II).
The final specimens were available in all cases. Invasion was identified in the final specimens of 58 (41.4%) cases of ductal carcinoma in situ (DCIS). When the data were divided according to nuclear grade, 9% (2/21) of DCIS-1 cases, 38.7% (19/49) of DCIS-2 cases, and 52.8% (37/70) of DCIS-3 cases exhibited upstaging to invasion. There was a statistically significant increase in the rate of invasion from DCIS-1 to DCIS-3 (p < 0.05). In the initial biopsies of cases in which invasion was upstaged, 40 cases exhibited a solid histologic pattern, 14 cases exhibited a cribriform pattern, two cases exhibited a micropapillary pattern, and one case each exhibited a flat and papillary dominant pattern (Figure 1). The invasion rate was 57% (40/70) for all solid DCIS cases, 25.9% (14/54) for cribriform DCIS cases, and 25% (2/10, 1/2 and 1/4) for micropapillary DCIS, flat DCIS, and papillary DCIS cases. The rate of invasion in the final specimens of patients diagnosed with solid DCIS was significantly higher than in those with other patterns (p < 0.05) (Figure 2). Invasion was identified in the final specimens of 48 (88.8%) of the 54 DCIS cases with comedonecrosis. The rate was 11.6% in those without comedonecrosis (10/86).
Table II: Histopathologic and immunohistochemical characteristics of ductal carcinoma in situ cases
Table III: Invasion relationship of immune and histologic features of DCIS cases
The presence of comedonecrosis was found to be a significant predictor of upstaging in DCIS cases (p < 0.05).
The relationship between the immune profile of DCIS cases and invasion is summarised in Table III. The results indicated that ER-/HER2- and ER-/HER2+ DCIS cases exhibited a markedly elevated risk of invasion in comparison to other cases (p < 0.05). When the two results were evaluated together, it was evident that ER negativity was a significant risk factor for invasion. Invasion was observed in one of two ER+/HER2+ cases, but the sample size was insufficient for statistical analysis (Figure 3). Upon analysis of the hormone pattern relationship, it was observed that the ER-/HER2+ profile-solid pattern exhibited a significantly higher association with invasion (p < 0.05), while the other immune profile pattern associations were not statistically significant (p > 0.05).
In conclusion, the statistical analysis revealed that the solid pattern, high nuclear grade, presence of comedonecrosis, and the ER-/HER2- immune profile were significant predictors of invasion in DCIS cases. Based on these results (A&D: H&E; B&E: ER antibody; C&F: HER2 antibody; 20X).
Table IV: Risk scoring for invasion upstage
and the findings of similar studies in the literature, an AIassisted invasion risk scoring system was developed.
A total risk score was calculated for each case according to the scoring system described in the material and method.
The invasion rates and risk groups were summarised in Table IV.
Upon analysis of the histomorphological and immunohistochemical features of the DCIS groups, it was observed that the DCIS-1 and DCIS-2 groups exhibited a cribriform predominant pattern and an ER+/HER2- profile with greater frequency, while the DCIS-3 cases demonstrated a predominant solid pattern and an ER-/HER2+ profile. Comedonecrosis was found to be correlated with high nuclear grade, a finding that was consistent with the existing literature [1].
The analysis revealed no statistically significant correlation between age and the presence of invasion in the final specimen. This finding aligns with the conclusions drawn in the existing literature [10]. In our study, the histologically solid predominant pattern was found to be generally associated with higher nuclear grade and more frequent invasion compared to other patterns. Furthermore, the solid pattern was observed to be associated with a higher incidence of comedonecrosis and HER2 positivity. While studies in the literature do not consistently identify a clear pattern, some studies have reported that the solid pattern is more frequently upstaged to invasion. However, other studies have indicated that the cribriform [13,32] papillary [9,32], and micropapillary [11] patterns are more frequently upstaged to invasion compared to other patterns. Conversely, some studies have indicated that there is no statistically significant correlation between histologic subtype and the detection of invasion in the final specimen [10,20,33]. In studies examining the relationship between DCIS and invasion, the most frequently reported predictive factors for invasion are high nuclear grade and comedonecrosis. In our study, 9%, 38.7% and 52.8% of cases with low, intermediate and high nuclear grade, respectively, were found to have invasion in the final specimens. Furthermore, 88.8% of cases with comedonecrosis and 11.6% of cases without, invasion upstaging were identified. The upstaging of invasion in the final specimens of all five cases with comedonecrosis in the DCIS-1 and DCIS-2 groups indicates that comedonecrosis is a predictive factor irrespective of nuclear grade. It has been demonstrated that comedonecrosis may serve as a predictor of tumour recurrence and invasion [11]. It is notable that a number of publications have also reported that nuclear grade and comedonecrosis are not predictive factors. In addition to the aforementioned data, there are several publications on lobular carcinogenesis, tumour size, periductal lymphocytic infiltrate, and calcification that address the predictive value of these factors. However, as these issues fall outside the scope of the present study, they will not be discussed further here.
In light of the predictive value of histomorphological data with lymph node involvement in cases where there is an upstage to invasion in the final specimens of cases diagnosed with ductal carcinoma in situ (DCIS) in tru-cut specimens, it was previously reported that only comedonecrosis may be predictive for lymph node involvement [21]. However, lymph node involvement was excluded from the study since all cases included in this study did not have lymph node sampling.
The ER-/HER2- immunoprofile was identified as a predictive factor for invasion in the course of our study. Furthermore, cases classified as ER-/HER2+ exhibited a statistically significant increase in invasion upstaging compared to those classified as ER+/HER2-. In analogous studies in the literature, it was reported that ER-/PR- DCIS was more prone to invasion; however, statistical significance was not found [17]. In another study, it was reported that an ER-/HER2+ profile was associated with a significant risk of invasion [13]. In contrast to the aforementioned studies, other research has indicated that the hormone profile is not a significant predictor of invasion.
In addition to the findings reported in the literature, our study identified a solid pattern and an ER-/HER2- immunoprofile as new predictive factors for invasion.
In the existing literature, risk classifications in DCIS cases are typically based on radiological data. In one study, a risk algorithm was developed by scoring histologically cribriform pattern, medium-high nuclear grade, and hormone negativity, as well as size. HER2 was not included in the scoring system. In the present study, a comprehensive pathological AI-assisted risk classification was devised, incorporating ER and HER2 status, as well as histopathological pattern, comedonecrosis and nuclear grade as criteria. To the best of our knowledge, this is the first study to employ pathologic risk scoring in terms of invasion in DCIS cases. The relatively low number of cases included in the risk scoring was identified as a limitation of the study.
A further limitation of this study is that the proposed AIbased invasion risk scoring system has not yet been validated in an independent external cohort. The establishment of the algorithm’s reproducibility, calibration, and real-world clinical applicability necessitates external validation in independent series, particularly those comprising matched tru-cut biopsy and resection specimens from different centres. This is due to the model’s development being undertaken using a single-centre retrospective series.
It is imperative to acknowledge that this model should be regarded as a preliminary derivation model rather than a final decision-making tool for clinical practice.
Conflict of Interest The authors declared that they have no conflict of interest.
Ethical Approval Approval was obtained from the Ethics Committee of Gaziantep University for the study.
Authorship Contributions Concept: EU, Design: EU, Data collection and/or processing: EU, KB, Analysis and/or interpretation: EU, KB, Literature search: EU, KB, Writing: EU, KB, Approval: EU.
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