DeepMSS: Deep Multi-Modality Segmentation-to-Survival Learning for Survival Outcome Prediction from PET/CT Images

Survival prediction is a major concern for cancer management. Deep survival models based on deep learning have been widely adopted to perform end-to-end survival prediction from medical images. Recent deep survival models achieved promising performance by jointly performing tumor segmentation with survival prediction, where the models were guided to extract tumor-related information through Multi-Task Learning (MTL). However, existing deep survival models have difficulties in exploring out-of-tumor prognostic information (e.g., local lymph node metastasis and adjacent tissue invasions). In addition, existing deep survival models are underdeveloped in utilizing multi-modality images. Empirically-designed strategies were commonly adopted to fuse multi-modality information via fixed pre-designed networks. In this study, we propose a Deep Multi-modality Segmentation-to-Survival model (DeepMSS) for survival prediction from PET/CT images. Instead of adopting MTL, we propose a novel Segmentation-to-Survival Learning (SSL) strategy, where our DeepMSS is trained for tumor segmentation and survival prediction sequentially. This strategy enables the DeepMSS to initially focus on tumor regions and gradually expand its focus to include other prognosis-related regions. We also propose a data-driven strategy to fuse multi-modality image information, which realizes automatic optimization of fusion strategies based on training data during training and also improves the adaptability of DeepMSS to different training targets. Our DeepMSS is also capable of incorporating conventional radiomics features as an enhancement, where handcrafted features can be extracted from the DeepMSS-segmented tumor regions and cooperatively integrated into the DeepMSS's training and inference. Extensive experiments with two large clinical datasets show that our DeepMSS outperforms state-of-the-art survival prediction methods.