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Class imbalance in out-of-distribution datasets: Improving the robustness of the TextCNN for the classification of rare cancer types

Journal Article · · Journal of Biomedical Informatics
 [1];  [2];  [3];  [4];  [5];  [6];  [7];  [8];  [9];  [10];  [11];  [12];  [2];  [2]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Vanderbilt Univ., Nashville, TN (United States)
  4. Univ. of Kentucky, Lexington, KY (United States)
  5. Louisiana State Univ., New Orleans, LA (United States)
  6. Rutgers Univ., New Brunswick, NJ (United States)
  7. Univ. of Utah, Salt Lake City, UT (United States)
  8. Fred Hutchison Cancer Research Center, Seattle, WA (United States)
  9. Univ. of New Mexico, Albuquerque, NM (United States)
  10. California Dept. of Public Health, Sacremento, CA (United States)
  11. Information Management Services, Inc., Calverton, MD (United States)
  12. National Cancer Institute, Bethesda, MD (United States)

In the last decade, the widespread adoption of electronic health record documentation has created huge opportunities for information mining. Natural language processing (NLP) techniques using machine and deep learning are becoming increasingly widespread for information extraction tasks from unstructured clinical notes. Disparities in performance when deploying machine learning models in the real world have recently received considerable attention. In the clinical NLP domain, the robustness of convolutional neural networks (CNNs) for classifying cancer pathology reports under natural distribution shifts remains understudied. In this research, we aim to quantify and improve the performance of the CNN for text classification on out-of-distribution (OOD) datasets resulting from the natural evolution of clinical text in pathology reports. We identified class imbalance due to different prevalence of cancer types as one of the sources of performance drop and analyzed the impact of previous methods for addressing class imbalance when deploying models in real-world domains. Our results show that our novel class-specialized ensemble technique outperforms other methods for the classification of rare cancer types in terms of macro F1 scores. We also found that traditional ensemble methods perform better in top classes, leading to higher micro F1 scores. Based on our findings, we formulate a series of recommendations for other ML practitioners on how to build robust models with extremely imbalanced datasets in biomedical NLP applications.

Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Argonne National Laboratory (ANL), Argonne, IL (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Organization:
USDOE Office of Science (SC); USDOE National Nuclear Security Administration (NNSA); Centers for Disease Control and Prevention (CDC); National Cancer Institute (NCI); University of Utah; Huntsman Cancer Foundation
Grant/Contract Number:
AC05-00OR22725; AC02-06CH11357; AC52-07NA27344; AC52-06NA25396
OSTI ID:
1884003
Journal Information:
Journal of Biomedical Informatics, Journal Name: Journal of Biomedical Informatics Journal Issue: 1 Vol. 125; ISSN 1532-0464
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

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