A compact texture frequency spatial gating network for oral cancer classification from clinical oral images

Image-level classification of oral-cavity photographs remains challenging because oral-cancer appearances are heterogeneous and many public datasets lack patient identifiers, acquisition metadata, biopsy confirmation, and lesion-level annotations. This study proposes OCAT-Net-S, a compact hierarchical network for binary classification of Normal versus Oral Cancer from RGB clinical oral images. The model combines a convolutional stem, MBConv blocks, MBConv-SE blocks, and Texture Frequency Spatial Gating (TFSG) blocks to integrate local texture extraction, channel recalibration, and frequency-guided spatial attention within a 3.55 M-parameter architecture. Internal evaluation used the Atef-Kaggle Oral Cancer Images for Classification dataset, containing 1,238 images: 553 Normal and 685 Oral Cancer. Because patient identifiers were unavailable, five-fold stratified group cross-validation with filename-sequential grouping was used as a leakage-reduction proxy and repeated across five seeds. OCAT-Net-S achieved an internal AUC-ROC of 0.956, oral-cancer F1-score of 0.942, and sensitivity of 0.942, compared with AUC-ROC 0.941 for the strongest evaluated baseline, TinyViT-5 M. Validation-only temperature scaling produced a mean Brier score of 0.0419, ECE-15 of 0.0174, and NLL of 0.1798. To reduce overinterpretation from repeated seed runs, fold-level inference was reported, giving an internal AUC-ROC estimate of 0.956 with an approximate 95% CI of 0.940-0.972. External transfer testing was performed without external threshold tuning on two independent settings: SMART-OM Normal-versus-OSCC and the Oral Images Dataset benign-versus-malignant oral-lesion task. AUC-ROC decreased to 0.830 and 0.840, respectively, indicating measurable cross-dataset shift despite partial transferability. Qualitative Grad-CAM visualizations suggested lesion-focused activation patterns, but lesion-level masks were unavailable for quantitative localization validation. Overall, OCAT-Net-S demonstrates compact internal image-level discrimination and limited external transferability; however, the findings do not establish patient-level generalization, prospective clinical validity, clinician-equivalent performance, or deployment readiness.