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Longitudinal deep learning models for integrating patient-reported outcomes in toxicity and survival prediction of head and neck cancer
Dissertation

Longitudinal deep learning models for integrating patient-reported outcomes in toxicity and survival prediction of head and neck cancer

Yaohua Wang
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Spring 2025
DOI: 10.25820/etd.007868
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PhD_Thesis_Dissertation_of_Studying_the_Impact_of_Long_Short_Term_Memory__LSTM__on_Patient_reported_Outcome__PRO_Camera_Ready6.43 MB
Embargoed Access, Embargo ends: 06/26/2027

Abstract

In clinical practice, head and neck cancer (HNC) patients usually have severe side effects during the cancer treatment that subsides over time. However, some patients have persistent late toxicity that negatively affects the patient's quality of life (QoL) after the treatment. To monitor patients' symptom burden, clinicians often collect symptom ratings directly from patients using symptom questionnaires known as patient-reported outcome (PRO) measures. These PRO can be collected repeatedly over time and could be used to better inform treatment decisions. However, their incorporation into clinical practice presents numerous challenges. First, missing data are common if patients skip certain questions or entire questionnaires. Second, PROs are subjective: a symptom rating of 5 for one patient could be a 10 for another. Finally, only a subset of patients experience late toxicity, while most see their symptoms diminish over time. To address these challenges, we implement and evaluate a family of Long Short-Term Memory (LSTM) recurrent neural networks used for imputing missing values and predicting patients' late toxicity. To normalize the PRO ratings, we subtract the baseline from subsequent ratings, and the use of symptom clusters gives us a more balanced toxicity distribution. Our experiments show that LSTM-based methods effectively handle missing-value imputation and late-toxicity prediction, outperforming more standard machine learning and other statistical approaches. Building on these predicted symptom ratings and sequential treatment variables, we developed a Symptom Burden Model (SBM) to generate a binary (low/high) long-term indicator of symptom burden, i.e. 12 months after treatment. This indicator was then incorporated into a Cox regression model, alongside other clinical features, to predict overall survival. Our results show that including the long-term symptom burden indicator in the Cox model increased the test c-index from 0.804 to 0.849, demonstrating a notable improvement in survival prediction.
Bidirectional Long Short-Term Memory (Bi-LSTM) Late Toxicity Patient Reported Outcomes (PROs) Survival Prediction Symptom Burden Prediction Symptom Severity Prediction

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