CoRe-WM: Conditioned Response-State World Modeling for Longitudinal Treatment-Response Prediction in Breast DCE-MRI
Authors: Lin Zhao, Bowen Chen, Qiaohui Gao, Shaowen Wan, Xiang Li, Wei Liu, Tianming Liu
Organizations: Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ 07102, USA. · College of Engineering, Northeastern University, Boston, MA 02115, USA. · Department of Radiology, Massachusetts General Hospital, Boston, MA 02114, USA. · Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ 85054, USA. · School of Computing, University of Georgia, Athens, GA 30602, USA.
Pathologic complete response (pCR) after neoadjuvant chemotherapy is a key prognostic indicator in aggressive breast cancer, yet existing prediction approaches either rely on pretreatment imaging alone, missing the patient's evolving response, or optimize multi-visit classifiers under direct outcome supervision, coupling representation learning with the clinical endpoint. We formulate longitudinal pCR prediction as a world-modeling problem and propose Conditioned Response-state World Modeling (CoRe-WM), which learns a latent state-transition model that predicts the next imaging state from the observed sequence. The transition function is conditioned on patient clinical profile and assigned therapy through additive shift and feature-wise modulation, enabling patient- and treatment-specific dynamics. A Factorized Response State pathway further decouples treatment-response dynamics from imaging appearance by encoding the structural prior that response manifests primarily in lesion morphology. After pretraining, all parameters are frozen and a linear readout predicts pCR at each clinical decision point. We evaluate CoRe-WM on I-SPY2 under five-fold cross-validation and assess cross-cohort transfer on I-SPY1. CoRe-WM achieves the highest discrimination among all evaluated methods at every prospective decision point, and demonstrates robust cross-cohort transfer. Ablation studies identify patient-profile conditioning and the factorized response pathway as the principal contributors. These results establish world-model-based representation learning as a promising framework for outcome prediction in oncology and beyond.
Figures & tables
Fig. 1 : Overview of CoRe-WM . (A) Outcome-free pretraining. The upper pathway encodes DCE-MRI visits into latent states and predicts the next latent via a conditioned causal Transformer; the lower pathway operates on lesion geometry descriptors to produce a factorized response state s^t+1 , which corrects the latent prediction and is supervised by the IRG loss. Patient profile, treatment, and temporal embeddings condition both pathways through FiLM modulation [ 43 ] . The EMA target encoder [ 44 ] provides the stable prediction target. (B) pCR prediction. All parameters are frozen; accumulated response states at each decision point are passed to a linear readout for progressively updated pCR estimates.
Method
Avail. MRI
AUROC
AUPRC
Acc.
Sens.
Spec.
Pretreatment methods
ViT [ 23 ]
T0
0.5591±0.0320
0.4064±0.0156
0.5657±0.0507
0.5164±0.1935
0.5917±0.1741
ViT + two-stage fusion [ 23 ]
T0
0.5950±0.0130
0.4230±0.0194
0.5521±0.0629
0.5745±0.2431
0.5412±0.2194
3-D ResNet
T0
0.5444±0.0391
0.3685±0.0242
0.4977±0.0617
0.6836±0.1546
0.4022±0.1661
Longitudinal methods
PrefixGRU
T0–T2
0.5784±0.0668
0.4157±0.0799
0.5718±0.0514
0.4982±0.2075
0.6098±0.1709
Temp. repr. learning [ 34 ]
T0–T2
0.5179±0.0516
0.3710±0.0559
0.5606±0.0476
0.3527±0.2079
0.6678±0.1748
Two-stage dual-task [ 33 ]
T0–T1
0.6958±0.0193
0.5412±0.0378
0.6435±0.0323
0.5745±0.0539
0.6792±0.0600
TABLE I : Five-fold I-SPY2 comparison using the same patient splits and seed for all methods. Values are fold mean ± standard deviation. The “Available MRI” column lists the examinations used by the pCR predictor; T3 may additionally be used as an outcome-free pretraining target ( CoRe-WM and BSTNet temporal-order pretraining). ViT two-stage fusion uses the complete BreastDCEDL clinical and geometry feature set. Accuracy, sensitivity, and specificity use a validation-selected threshold.
Method
Avail. MRI
AUROC (95% CI)
AUPRC
Acc.
Sens.
Spec.
Pretreatment methods
ViT [ 23 ]
T0
0.5584[0.4549,0.6609]
0.3159
0.4872
0.6829
0.4174
ViT + two-stage fusion [ 23 ]
T0
0.5750[0.4764,0.6746]
0.3276
0.4487
0.6585
0.3739
3-D ResNet
T0
0.6738[0.5698,0.7709]
0.4213
0.2949
0.9512
0.0609
Longitudinal methods
PrefixGRU
T0–T2
0.6494[0.5510,0.7428]
0.3798
0.6282
0.6341
0.6261
Temp. repr. learning [ 34 ]
T0–T2
0.5548[0.4519,0.6579]
0.3433
0.7308
0.0732
0.9652
Two-stage dual-task [ 33 ]
T0–T1
0.7635[0.6780,0.8402]
0.5391
0.7372
0.2439
0.9130
TABLE II : Cross-cohort transfer from I-SPY2 to 156 I-SPY1 patients (41 pCR). AUROC brackets are patient-bootstrap 95% confidence intervals. All pCR supervision, model selection, and operating-threshold selection use I-SPY2 only.
Cumulative configuration
Profile
Tx
Geo
FRS/IRG
AUROC
Δ AUROC
Image-only JEPA
–
–
–
–
0.5816±0.0316
–
+ patient profile
✓
–
–
–
0.7135±0.0117
+0.1319±0.0350
+ treatment conditioning
✓
✓
–
–
0.7115±0.0393
−0.0019±0.0467
+ ROI geometry
✓
✓
✓
–
0.7380±0.0138
+0.0264±0.0451
+ factorized response state
✓
✓
✓
FRS
0.7506±0.0473
+0.0126±0.0442
+ image-derived response guidance ( CoRe-WM )
✓
✓
✓
FRS+IRG
0.7545±0.0468
+0.0039±0.0082
TABLE III : Cumulative five-fold ablation at T0–T1. Values are fold mean ± standard deviation. Δ AUROC is relative to the preceding row. Patient profile includes HR, HER2, MammaPrint, and age; Tx denotes treatment conditioning; Geo denotes ROI geometry. FRS and IRG denote factorized response state and image-derived response guidance, respectively.
Fig. 2 : Five-fold diagnostic analyses. (a) OOF calibration curves at three prospective decision points; points show equal-frequency bins with Wilson 95% CIs. (b) Decision-curve analysis for non-pCR identification; shaded regions are bootstrap 95% CIs. (c) Condition-dependence analysis; MRI latents and geometry are fixed while treatment, clinical profile, or their joint context is permuted; shaded regions show ±1 SD across folds. (d) Response-state grounding; a ridge probe maps the frozen T0-to-T2 state update to observed log-volume shrinkage in 791 OOF patients.
Subtype
n (pCR%)
T0
T0–T1
T0–T2 (95% CI)
Overall
808
(34.0)
0.733
0.755
0.762
HR+/HER2 −
320
(17.8)
0.683
0.689
0.705 [0.616, 0.784]
HER2+
201
(46.8)
0.712
0.741
0.731 [0.658, 0.801]
TNBC
287
(43.2)
0.640
0.669
0.707 [0.646, 0.765]
TABLE IV : Receptor-subtype stratification of CoRe-WM five-fold OOF AUROC at each prospective decision point. Values are pooled out-of-fold AUROC; brackets are patient-bootstrap 95% confidence intervals.
Pathologic complete response (pCR) is an important endpoint in neoadjuvant chemotherapy (NAC) for breast cancer, and predicting pCR from imaging during treatment could support treatment response assessment. Many existing imaging-based approaches rely on a single static timepoint, which fails to capture changes that occur during treatment. In this work, we present a longitudinal framework that combines a frozen 3D foundation encoder (Pillar-0) with our Temporal Dynamics Network (TDN) to predict treatment response from serial Dynamic Contrast-Enhanced (DCE) MRI acquired across four clinical timepoints from pre-treatment to pre-surgery. The TDN combines time-aware volumetric embeddings with clinical and treatment data to predict pCR. Evaluated on 982 patients from the combined I-SPY2 and ACRIN-6698 cohort, the proposed model achieves strong performance across all reported metrics when longitudinal 3D imaging is fused with clinical data (test AUROC: 73.6%, balanced accuracy: 69.1%). While clinical variables provide the strongest individual predictive signal, longitudinal 3D imaging contributes complementary information when fused with clinical data, improving pCR prediction. Our source code is available at: https://github.com/omarftt/longitudinal_temporal_pillar.
Fidel Omar Tito Cruz, Neda Ghafouri, Zengyan Wang +3
In patients with breast cancer, pathological complete response (pCR) has been established as a clinically meaningful surrogate marker for long-term outcomes. While commonly treated with neoadjuvant chemotherapy (NACT), effective treatment decision-making remains challenging, as therapeutic response can vary substantially across patients, calling for predictive models capable of accurately estimating individualized treatment response. To address this, we propose an imaging-based 3D spatio-temporal framework for treatment response prediction that integrates a state-of-the-art graph neural network with relational modeling of temporal interactions across timepoints alongside three novel complementary self-supervised treatment trajectory representation learning objectives. Experiments across a cohort of 585 patients from the public ISPY-2 dataset demonstrate that our method substantially outperforms both vision and self-supervised learning baselines across several classification metrics. Alongside establishing a breast cancer pCR prediction benchmark, we include a principled ablation of our method and further introduce and empirically assess the impact of the available number of DCE-MRI timepoints per patient trajectory and the inclusion of inter-scan time-differences. Overall, our study substantiates the utility of clinically meaningful longitudinal medical imagaging modeling for predicting NACT-induced pCR. We will publicly share our code repository and a user-friendly PyPI library for dataset curation upon publication, effectively promoting reproducible open-source research.
Johannes Kiechle, Richard Osuala, Daniel M. Lang +5
Technical University of Munich · TUM University Hospital Rechts der Isar · Helmholtz Munich +4
Prediction of pathological complete response before neoadjuvant chemotherapy may facilitate more tailored therapeutic planning for breast cancer patients. This work proposes a deep-learning model for pretreatment data only, combining apparent diffusion coefficient maps, dynamic contrast-enhanced magnetic resonance imaging, and clinical variables. The study uses the public ACRIN 6698/I-SPY2 multicenter dataset. The architecture employs EfficientNet-B0 pretrained encoders for image feature extraction and late fusion with clinical information. Multiple clinical variables were evaluated, including age, race, histological type, HR/HER2 subtype, SBR grade, and maximum diameter. Only HR/HER2 subtype improved the average area under the receiver operating characteristic curve (AUC) and was retained in the final model. Using stratified five-fold cross-validation, standalone apparent diffusion coefficient maps achieved a mean AUC of 0.79, whereas dynamic contrast-enhanced magnetic resonance imaging achieved 0.74. Adding HR/HER2 subtype improved performance to 0.83 and 0.81, respectively. The final configuration, using both imaging modalities and HR/HER2 subtype, achieved an AUC of 0.86. These results support pretreatment multimodal learning for response prediction, although external validation is required before clinical use.
Pablo García Marcos, Paula Puerta González, Guillermo Lorenzo +6
Computer Science Department, University of Oviedo, Asturias, Spain · Biomedical Engineering Center (BME), University of Oviedo, Asturias, Spain · Electrical Engineering Department, University of Oviedo, Asturias, Spain +7