Organizations: Division of Computational Health Sciences, Department of Surgery, University of Minnesota, Minneapolis, MN, USA. · University of North Carolina at Chapel Hill, Chapel Hill, NC, USA. · North Carolina State University, Raleigh, NC, USA. · Centre for Innovation & Precision Eye Health, Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. · Institute of High Performance Computing, Agency for Science, Technology and Research, Singapore.
Multimodal self-supervised pretraining offers a promising route to cancer prognosis by integrating histopathology whole-slide images, gene expression, and pathology reports, yet most existing approaches require fully paired and complete inputs. In practice, clinical cohorts are fragmented and often miss one or more modalities, limiting both supervised fusion and scalable multimodal pretraining. We propose PRIME, a missing-aware multimodal self-supervised pretraining framework that learns robust and transferable representations from partially observed cohorts. PRIME maps heterogeneous modality embeddings into a unified token space and introduces a shared prototype memory bank for latent-space semantic imputation via patient-level consensus retrieval, producing structurally aligned tokens without reconstructing raw signals. Two complementary pretraining objectives: inter-modality alignment and post-fusion consistency under structured missingness augmentation, jointly learn representations that remain predictive under arbitrary modality subsets. We evaluate PRIME on The Cancer Genome Atlas with label-free pretraining on 32 cancer types and downstream 5-fold evaluation on five cohorts across overall survival prediction, 3-year mortality classification, and 3-year recurrence classification. PRIME achieves the best macro-average performance among all compared methods, reaching 0.653 C-index, 0.689 AUROC, and 0.637 AUROC on the three tasks, respectively, while improving robustness under test-time missingness and supporting parameter-efficient and label-efficient adaptation. These results support missing-aware multimodal pretraining as a practical strategy for prognosis modeling in fragmented clinical data settings.
Figures & tables
Fig. 1: Overview of the proposed PRIME framework for multimodal cancer prognosis with missing modalities. Left (Sample Pre-processing): Frozen encoders extract token embeddings from WSIs, RNA-seq, and pathology reports. Middle (Missing Modality Imputation): In a unified token space, a shared sequence-level prototype memory bank imputes missing modalities via patient-level consensus retrieval, followed by modality-specific refinement. Right (Missing-aware Pretraining): Two complementary objectives, inter-modality contrastive alignment and post-fusion consistency under modality/token dropout with prototype mixtures, jointly drive self-supervised pretraining.
Cancer
Ntri
OS
3yOS
3yRec
UCEC
499
80 / 419
62 / 203
99 / 176
LUAD
436
157 / 279
118 / 114
159 / 86
LGG
434
95 / 339
64 / 126
121 / 96
BRCA
855
116 / 739
56 / 357
69 / 340
BLCA
346
161 / 185
147 / 74
145 / 61
TABLE I: Per-cancer cohort statistics for downstream evaluation using tri-modal complete cases. Ntri denotes the tri-modal cohort size. OS entries are reported as event/cens . 3yOS and 3yRec entries are reported as pos/neg after excluding patients censored before 3 years; for 3yRec, excluded cases are those censored before 3 years without a recorded event.
Methods
Modalities
UCEC
LUAD
LGG
BRCA
BLCA
Avg
Img
RNA
Text
Img-only
✓
0.668 ± 0.083
0.599 ± 0.056
0.670 ± 0.100
0.615 ± 0.087
0.547 ± 0.060
0.620 ± 0.052
RNA-only
✓
0.598 ± 0.094
0.510 ± 0.057
0.764 ± 0.056
0.498 ± 0.065
0.526 ± 0.043
0.579 ± 0.110
Text-only
✓
0.676 ± 0.066
0.553 ± 0.028
0.703 ± 0.097
0.556 ± 0.030
0.532 ± 0.025
0.604 ± 0.079
ABMIL [ 34 ]
✓
0.637 ± 0.049
0.604 ± 0.066
0.692 ± 0.056
0.617 ± 0.092
0.537 ± 0.035
0.617 ± 0.056
SNN [ 35 ]
✓
0.571 ± 0.070
0.520 ± 0.065
0.719 ± 0.073
0.466 ± 0.103
0.536 ± 0.053
0.563 ± 0.096
TABLE II: Task-1 overall survival performance (C-index) on five cancer cohorts. Values are mean ± std over 5-fold CV within each cohort; Avg denotes the mean ± std across cohorts. Best and second-best results are highlighted in bold and underline .
Methods
Task-2 Avg
Task-3 Avg
Img-only
0.640 ± 0.070
0.572 ± 0.087
RNA-only
0.587 ± 0.099
0.561 ± 0.117
Text-only
0.619 ± 0.070
0.608 ± 0.071
ABMIL [ 34 ]
0.638 ± 0.064
0.591 ± 0.080
SNN [ 35 ]
0.594 ± 0.110
0.568 ± 0.107
Early
0.655 ± 0.082
0.609 ± 0.060
TABLE III: Average AUROC across five cancer cohorts for Task-2 (3-year mortality) and Task-3 (3-year recurrence). Values are mean ± std across cohorts. Best and second-best methods are highlighted within each task.
Fig. 2: Kaplan–Meier survival curves based on predicted risk scores for five TCGA cohorts. Each panel reports the log-rank p -value and the hazard ratio (HR) from a univariate Cox model comparing high-risk vs. low-risk groups.
Task
Method
Full
LI
LR
LT
OI
OR
OT
Task-1
Scratch (FT)
0.623 ± 0.072
0.608 ± 0.069
0.631 ± 0.068
0.607 ± 0.051
0.607 ± 0.050
0.540 ± 0.085
0.606 ± 0.066
Pretrained (LP)
0.653 ± 0.086
0.612 ± 0.086
0.641 ± 0.086
0.619 ± 0.090
0.603 ± 0.058
0.564 ± 0.084
0.611 ± 0.077
Pretrained (LP+Missing)
0.653 ± 0.089
0.623 ± 0.085
0.639 ± 0.085
0.636 ± 0.087
0.611 ± 0.055
0.571 ± 0.063
0.610 ± 0.089
Task-2
Scratch (FT)
0.656 ± 0.064
0.611 ± 0.052
0.666 ± 0.064
0.621 ± 0.073
0.620 ± 0.072
0.486 ± 0.051
0.611 ± 0.052
Pretrained (LP)
0.689 ± 0.110
0.670 ± 0.118
0.671 ± 0.097
0.665 ± 0.088
0.638 ± 0.077
0.618 ± 0.112
0.641 ± 0.101
Pretrained (LP+Missing)
0.679 ± 0.117
0.679 ± 0.118
0.670 ± 0.104
0.676 ± 0.089
0.642 ± 0.077
0.627 ± 0.118
0.646 ± 0.107
TABLE IV: Robustness to missing modalities on three downstream tasks. Models are trained on full tri-modal data, with missingness introduced only at test time. Full denotes all modalities; LI/LR/LT and OI/OR/OT denote leave-one-out and only-one settings for Image/RNA/Text, respectively. Values are mean ± std over 5-fold CV.
Fig. 3: Label-efficient downstream transfer performance on Task-1 (overall survival; C-index). The x-axis denotes the fraction of labeled training samples retained from the full training split. Left: unimodal baselines. Right: multimodal fusion baselines.
Variant
Components / Objective
Downstream performance
Pretrained Data (missing+full modality)
Prototypes
Lalign
Lfusion
T1 (C-index)
T2 (AUROC)
T3 (AUROC)
w/o prototypes (token=0)
✓
×
✓
✓
0.646 ± 0.082
0.669 ± 0.123
0.595 ± 0.108
w/o missing modality
×
✓
✓
✓
0.640 ± 0.074
0.656 ± 0.116
0.629 ± 0.087
Full method (Pretrained LP)
✓
✓
✓
✓
0.653 ± 0.086
0.689 ± 0.110
0.629 ± 0.098
w/o Lalign ( λ=0 )
✓
✓
×
✓
0.614 ± 0.072
0.625 ± 0.087
0.626 ± 0.065
w/o Lfusion ( λ=1 )
✓
✓
✓
×
0.589 ± 0.068
0.624 ± 0.129
0.609 ± 0.093
TABLE V: Ablation on key components of our pretraining framework. All variants use the same downstream protocol (pretrained + LP) and are evaluated on the five-cohort average (mean ± std over 5-fold CV). Full method uses missing-aware pretraining, prototypes, and the combined objective L=λLalign+(1−λ)Lfusion . “w/o Lalign ” corresponds to λ=0 , and “w/o Lfusion ” corresponds to λ=1 .
Fig. 4: Sensitivity of the model to prototype bank size Kc (left) and loss weight coefficient λ (right).
Multimodal pretraining learns reusable representations by training models on paired or mixed data from multiple modalities, such as text, images, audio, and signals.
AI for Image-Guided Diagnosis and Therapy, School of Medicine and Health, Technical University of Munich (TUM), Munich, Germany · Munich Center for Machine Learning (MCML), Munich, Germany · Technical University of Munich (TUM), Munich, Germany +2