In this study, a novel approach for radiomics and dosiomics analysis was proposed. The treatment failure prediction model was able to stratify patients into low- and high-risk groups, the DD-LT and CD-RLT models may play a role in predicting treatment failure after CRT in patients with PSCC.
Keek et al. developed two radiomic-based models to predict LRR and DM after CRT in patients with HNSCC [8]. C indices for prediction performance were 0.52 for radiomics-LRR and 0.49 for the radiomics-DM models. Our topology-based DD-LT and CD-RLT models demonstrated the C-indices of 0.74 and 0.64, respectively. Therefore, our proposed novel approach can accurately predict treatment failure prior to treatment planning in patients with PSCC.
Wu et al. developed recurrence prediction models for patients with HNSCC [9]. The C-index of the conventional CT radiomics model was 0.54. The C-indices of the dosiomics and combined with the CT radiomics and dosiomics models were 0.60 and 0.60, respectively. By comparing our treatment failure prediction models (DD-LT and CD-RLT models) with their recurrence prediction models, our treatment failure models achieved a higher C-indices (0.74 and 0.64) than their models. Therefore, the treatment failure prediction performance after CRT in patients with PSCC may be improved by applying the topology or local binary pattern to conventional radiomics/dosiomics models. However, they reported that the CT radiomics/dosiomics prediction model combined with PET data showed improvement, with a C-index of 0.66. Hence, our model can potentially be improved by applying radiomics features extracted from PET images. Therefore, incorporation of PET images should be investigated in future studies.
LR, LRR, DM, and residual tumor were defined as treatment failures in this study owing to the insufficient number of cases for each outcome. This study aimed to predict treatment failure in patients with LR, LRR, DM, or residual tumors. Treatment failure is primarily caused by tumor resistance. Resistant tumor cells can survive treatment (residual tumor), contribute to LR and LRR, or lead to the development of DM. Thus, our approach may be able to extract resistant tumor cells from the phenotype in medical images through a more detailed analysis in the future.
This study had some limitations. First, interobserver variability in tumor delineation was not considered. This may affect the robustness and generalizability of the radiomics-based prediction models. Pavic et al. reported that the stability rate of radiomic features with respect to inter-observer delineation variability was 59% in HNSCC [32]. This could be due to the inclusion of several tumor sites. Therefore, it is necessary to limit the number of tumor sites used in the analysis as much as possible. Moreover, employing consensus-based approaches, such as obtaining agreement among multiple observers or expert consensus, may help mitigate inter-observer delineation variability. In addition, automated or semiautomated delineation techniques may address the problem of interobserver variability.
Second, treatment planning can vary by facility, planners (i.e., oncologists and medical physicists), years of experience, and dose calculation algorithms, leading to differences in the calculated dose distributions. This variability can affect the reliability and reproducibility of the dosiomic analyses. Bufacchi et al. calculated the target dose for nasopharyngeal carcinomas with the two dose-calculation algorithms [33]. As a result, the difference in tumor control probability reached 6.8%. Therefore, it is necessary to investigate the reliability and reproducibility of the dosiomic analysis of the prediction models in future studies.
Third, the number of selected features was not optimized for the construction of treatment failure prediction models. The optimal number of features for each model can differ. Therefore, there is scope for further study on the optimization of the number of selected features.
Finally, the treatment failure prediction model developed in this study is based on a limited number of patients with PSCC (n = 224). Therefore, it may be crucial to ensure an appropriate number of patients in order to improve the performance of treatment failure prediction models. Thus, a longitudinal study with a larger sample size is required to assess the reliability of these results.