Evaluating the Sensitivity–Specificity Trade-off in Risk Factor-Based Cervical Cancer Classification Using SMOTE and ACO-Optimized XGBoost

Titin Prihatin (Universitas Bina Sarana Informatika)
Suharjanti Suharjanti (Universitas Bina Sarana Informatika)
Resti Lia Andharsaputri (Universitas Bina Sarana Informatika)
Hafis Nurdin (Universitas Bina Sarana Informatika)

Sinkron : Jurnal dan Penelitian Teknik Informatika
Vol. 10 No. 4 (2026): Research Articles October 2026

Class imbalance is a major challenge in risk factor-based cervical cancer classification because positive cases are substantially less frequent than negative cases. This study aims to evaluate the effects of the Synthetic Minority Over-sampling Technique (SMOTE) and Ant Colony Optimization (ACO) on XGBoost performance and to investigate the trade-off between sensitivity, specificity, and overall discriminative ability. The Cervical Cancer (Risk Factors) dataset from the UCI Machine Learning Repository, containing 858 observations, was used with Biopsy as the binary classification target, comprising 803 negative and 55 positive cases. A total of 28 risk-factor features were retained after excluding diagnostic attributes with potential data leakage. Three classification scenarios were evaluated: XGBoost, SMOTE-XGBoost, and SMOTE-ACO-XGBoost. Model performance was assessed using Nested Repeated Stratified Cross-Validation, consisting of an outer 5-fold cross-validation repeated five times and an inner 3-fold cross-validation for hyperparameter and decision-threshold optimization. The results showed that SMOTE-XGBoost achieved the highest recall of 0.4182 ± 0.3340, whereas SMOTE-ACO-XGBoost obtained the highest accuracy of 0.7667 ± 0.1698 and specificity of 0.8042 ± 0.1950. Baseline XGBoost achieved the highest ROC-AUC and PR-AUC values of 0.6227 ± 0.0663 and 0.1290 ± 0.0739, respectively. The Friedman test indicated significant differences among the models across all evaluation metrics. Pairwise Wilcoxon signed-rank tests with Holm correction showed that ACO significantly improved accuracy and specificity compared with SMOTE-XGBoost but significantly reduced recall from 0.4182 to 0.2182. These findings demonstrate that class-imbalance handling and hyperparameter optimization do not produce a single model that consistently dominates all performance measures. SMOTE tends to improve sensitivity, whereas ACO optimization shifts the classifier toward higher accuracy and specificity at the cost of reduced sensitivity.