Disentangling Lung-Cancer CT/LDCT AI: A Systematic Evidence Map of Clinical Tasks, Evidence Chains, and Translational Gaps
Abstract
Artificial-intelligence studies using computed tomography (CT) for lung cancer are often broadly labelled "prediction" despite addressing clinically distinct tasks. We systematically mapped CT/low-dose CT (LDCT)-centered lung-cancer AI using five-database retrieval, full-text eligibility assessment, role-aware modality/omics extraction, clinical-task classification, and a Multi-Tier Evidence Graph (MTEG). The final corpus comprised 293 studies (2016-2026): 230 Detection, 8 future Risk-prediction, and 55 Other studies. Clinical variables (96.2%), 3D CT/LDCT (73.0%), and radiomics (63.5%) predominated, whereas external validation (29.0%), calibration (20.5%), decision-curve analysis (13.0%), longitudinal CT (17.7%), and saliency/attribution XAI (21.5%) were less frequent. The MTEG comprised 377 nodes and 3,444 edges; only 31 studies (10.6%) completed the six-tier substantive evidence chain, with greatest attrition at reasoning/explanation. Overall, the literature is detection-dominated, genuine future risk prediction remains uncommon, and complete translational evidence chains are rare.
Figures & tables
| Element | Operational definition |
|---|---|
| Population | Individuals or cohorts evaluated in lung-cancer screening, pulmonary-nodule assessment, lung-cancer diagnosis, future cancer-risk estimation, prognosis, treatment-response assessment, or another prespecified clinically relevant thoracic-oncology setting. |
| Index / intervention | AI-, machine-learning-, deep-learning-, computer-vision-, or radiomics-based analysis in which CT or LDCT is an analytical input or central imaging component; eligible multimodal extensions could additionally incorporate clinical, longitudinal, molecular, image–text, or other complementary information. |
| Comparator | Radiologist assessment, pathological or clinical reference standards, conventional risk models, alternative AI/ML models, baseline algorithms, or no explicit comparator when the eligible report was primarily a model-development or validation study. |
| Outcomes | Future lung-cancer incidence/risk; current lesion or disease detection, segmentation, diagnosis, screening classification, or pulmonary-nodule malignancy; and prespecified related endpoints including prognosis, survival, recurrence, treatment response, staging/progression, lung function, or molecular status. |
| Study design | Peer-reviewed primary empirical studies reporting development, evaluation, validation, or clinically relevant application of an eligible CT/LDCT-centered computational approach. Reviews, surveys, editorials, dataset-only publications, abstract-only reports, retracted publications, and other non-eligible document types were excluded. |
| Domain | Inclusion criterion | Exclusion criterion |
|---|---|---|
| Clinical scope | Lung cancer, pulmonary nodules, lung-cancer screening, or another directly relevant thoracic-oncology endpoint. | Primary focus outside lung cancer/pulmonary nodules or an off-target clinical problem without an eligible lung-cancer endpoint. |
| Imaging scope | CT/LDCT used as a primary analytical input or central imaging component, including eligible multimodal extensions. | No qualifying CT/LDCT contribution to the analytical model or evidence pathway. |
| Methodological scope | AI, machine learning, deep learning, computer vision, radiomics, or an eligible multimodal computational model. | No eligible computational modeling component or purely non-computational analysis. |
| Publication type | Peer-reviewed primary empirical research with sufficient methodological and outcome information. | Review/survey, editorial/commentary, dataset-only publication, abstract-only record, retracted article, non-peer-reviewed report, or another non-eligible document type. |
| Full-text availability | Full text sufficiently accessible to determine eligibility and extract the required evidence. | Unavailable/inaccessible full text or a document too incomplete for reliable eligibility assessment. |
| Language | Full text assessable under the review protocol which considers English or in a language that could be reliably assessed by the review team. | Full text not assessable under the review language protocol. |
| Task | Classification criterion |
|---|---|
| Risk prediction | Estimates an individual’s susceptibility to, or probability of, developing lung cancer in the future, before an established malignant lesion is being evaluated. This category includes future lung-cancer incidence, susceptibility, individualized risk estimation, and risk stratification. The defining feature is the future occurrence of lung cancer as the predicted endpoint, rather than characterization of a lesion already present at the time of assessment. |
| Detection | Identifies, localizes, segments, diagnoses, or characterizes lung cancer or pulmonary lesions that are already present at the time of assessment. This category includes lesion/nodule detection and segmentation, screening detection, diagnostic classification, benign-versus-malignant classification, and malignancy assessment of an existing pulmonary nodule. Accordingly, models estimating “malignancy probability,” “risk of malignancy,” or the likelihood that an existing nodule is malignant are classified as Detection rather than Risk prediction, despite the use of the term “risk.” |
| Others | Includes clinically relevant endpoints that concern neither future occurrence of lung cancer nor detection/characterization of currently present cancer or pulmonary lesions. These include prognosis, overall/progression-free/disease-free survival, recurrence, mortality, treatment response, treatment toxicity or adverse events, cancer staging or progression, pulmonary/lung function, and molecular or mutation-status prediction (e.g., EGFR, ALK, KRAS, or PD-L1), as well as other eligible endpoints outside the preceding two categories. |
| Measure | Definition | Interpretation in evidence synthesis |
|---|---|---|
| Component prevalence | Frequency of each evidence component across studies. | |
| Edge frequency | ; | Frequency/proportion with which two components are integrated. |
| Degree | [ 67 ] | Breadth of distinct direct component connections. |
| Strength | [ 68 ] | Cumulative recurrence of a component’s connections. |
| Betweenness | [ 69 ] | Bridging position between evidence regions. |
| Density | [ 67 ] | Proportion of possible pairwise connections observed. |
| Characteristic | Included studies |
|---|---|
| Total analytical corpus | 293 |
| Detection | 230 (78.5%) |
| Future Risk prediction | 8 (2.7%) |
| Other clinical tasks | 55 (18.8%) |
| Clinical variables | 282 (96.2%) |
| 3-D CT/LDCT | 214 (73.0%) |
| Component | % | 95% CI | Component | % | 95% CI | ||
|---|---|---|---|---|---|---|---|
| Clinical variables | 282 | 96.2 | 93.4–97.9 | External validation | 85 | 29.0 | 24.1–34.5 |
| 3-D CT/LDCT | 214 | 73.0 | 67.7–77.8 | Calibration | 60 | 20.5 | 16.3–25.5 |
| Radiomics | 186 | 63.5 | 57.8–68.8 | Decision-curve analysis | 38 | 13.0 | 9.6–17.3 |
| Saliency/attribution XAI | 63 | 21.5 | 17.2–26.6 | Longitudinal CT | 52 | 17.7 | 13.8–22.5 |
| Genomics | 19 | 6.5 | 4.2–9.9 | Transcriptomics | 7 | 2.4 | 1.2–4.8 |
| Multi-omics | 11 | 3.8 | 2.1–6.6 | Proteomics | 1 | 0.3 | 0.1–1.9 |
| Tier/role | Component | % | Tier/role | Component | % | ||
|---|---|---|---|---|---|---|---|
| Input | Clinical variables [ 1 ] | 282 | 96.2 | Validation | External validation [ 8 ] | 85 | 29.0 |
| Input | 3-D CT/LDCT [ 16 ] | 214 | 73.0 | Validation | Calibration [ 6 ] | 60 | 20.5 |
| Input | Radiomics [ 6 ] | 186 | 63.5 | Validation | Decision-curve analysis [ 6 ] | 38 | 13.0 |
| Input | 2-D CT/LDCT [ 2 ] | 108 | 36.9 | Reasoning | Saliency/attribution XAI [ 9 ] | 63 | 21.5 |
| Input | Longitudinal CT [ 24 ] | 52 | 17.7 | Reasoning | First-order logic/rules † [ 48 ] | 32 | 10.9 |
| Input | Genomics [ 77 ] | 19 | 6.5 | Input | Multi-omics [ 21 ] | 11 | 3.8 |
| Measure | Value |
|---|---|
| Mapped papers | 293 |
| MTEG nodes | 377 |
| MTEG edges | 3,444 |
| Complete six-tier chains | 31 |
| Complete-chain prevalence | 10.6% |
| Median substantive tiers covered | 5 |
| Concept | Papers | Degree | Between. |
|---|---|---|---|
| Classical ML | 165 | 0.253 | 0.004 |
| CNN | 210 | 0.253 | 0.009 |
| Binary diagnosis | 113 | 0.398 | 0.000 |
| Cancer-risk score | 61 | 0.434 | 0.000 |
| Uncertainty estimate | 86 | 0.398 | 0.000 |
| Nodule malignancy prob. | 70 | 0.422 | 0.000 |
| Network aspect | Observed result | Biomedical/AI interpretation |
|---|---|---|
| Paper-level semantic network | 293 papers; 3,404 edges; density 0.080 | The literature is selectively interconnected rather than uniformly similar; most possible paper–paper relationships are absent. |
| Connected components | 56 connected components | The evidence architecture contains multiple structurally separated regions. |
| Local organization | Mean clustering coefficient 0.346 | Similar papers tend to form local methodological neighborhoods, consistent with recurring combinations of related approaches. |
| MTEG evidence architecture | 377 nodes; 3,444 edges | The extracted evidence forms a large relational architecture linking clinical context, inputs, models, reasoning/explanation, outputs, and validation components. |
| Evidence-chain completeness | 31/293 complete chains (10.6%); median 5 tiers | Most studies cover several translational elements, but only about one in ten connects all six substantive tiers end-to-end. |
| Largest chain bottleneck | Model reasoning/explanation: 249 61 studies; conditional retention 24.5% | Explicit reasoning/explanation is the sharpest break in the cumulative translational chain, despite broad representation/model coverage. |
| Tier | Precision | Recall | F1 | |
|---|---|---|---|---|
| Patient/context | 0.928 | 0.978 | 0.952 | 0.144 |
| Input modality | 0.990 | 1.000 | 0.995 | 0.000 |
| Representation/model | 1.000 | 0.948 | 0.973 | 0.593 |
| Reasoning/explanation | 1.000 | 0.919 | 0.958 | 0.935 |
| Clinical output | 0.893 | 0.827 | 0.859 | 0.362 |
| Validation/quality | 1.000 | 0.828 | 0.906 | 0.555 |
| Detection | Risk | Others | ||||
| Tier | % | % | % | |||
| Patient/context | 225 | 97.8 | 8 | 100.0 | 50 | 90.9 |
| Input modality | 227 | 98.7 | 8 | 100.0 | 55 | 100.0 |
| Representation/model | 207 | 90.0 | 5 | 62.5 | 46 | 83.6 |
| Reasoning/explanation | 50 | 21.7 | 2 | 25.0 | 18 | 32.7 |
| Clinical output | 179 | 77.8 | 8 | 100.0 | 26 | 47.3 |
| Metric | Detection | Risk | Others |
|---|---|---|---|
| Papers | 230 | 8 | 55 |
| Concept nodes | 44 | 21 | 39 |
| Concept edges | 671 | 165 | 474 |
| Density | 0.709 | 0.786 | 0.640 |
| Connected components | 1 | 1 | 1 |
| Average clustering | 0.053 | 0.259 | 0.077 |
| D1 (All 16916 records) | D2 (Deduplicated records 9843) | D3 (Auto excluded record 9393) | D4 (Eligible Candidates 293) |
|---|---|---|---|
| Database-specific search strategies used for literature retrieval. | Obtained after the deduplication process. | Exclusion following low-confidence text assessment. | Frozen analytical corpus containing the final included studies and stable Record_ID information used for downstream analyses.. |
| D5 (Inelligible Candidates 107) | D6 (Backup records 50) | D7 (MTEG validation 293) | D8 (Risk of Bias 293) |
| Individual exempted according to specified exclusion principles). | PRISMA 2020 reporting crosswalk for the systematic evidence map. | Consolidated MTEG manual validation Consolidated Risk of Bias (RoB) report |
| Database-specific search strategy |
|---|
| PubMed ( "Lung Neoplasms"[Mesh] OR "lung cancer"[Title/Abstract] OR "lung carcinoma"[Title/Abstract] OR "pulmonary cancer"[Title/Abstract] OR "lung neoplasm*"[Title/Abstract] OR "pulmonary nodule*"[Title/Abstract] OR "lung nodule*"[Title/Abstract] OR "non-small cell lung cancer"[Title/Abstract] OR NSCLC[Title/Abstract] OR "small cell lung cancer"[Title/Abstract] OR SCLC[Title/Abstract] OR "lung adenocarcinoma"[Title/Abstract] OR "lung squamous cell carcinoma"[Title/Abstract] ) AND ( "Tomography, X-Ray Computed"[Mesh] OR "computed tomography"[Title/Abstract] OR "low-dose computed tomography"[Title/Abstract] OR "low-dose CT"[Title/Abstract] OR LDCT[Title/Abstract] OR "chest CT"[Title/Abstract] OR radiomics[Title/Abstract] OR "CT imaging"[Title/Abstract] ) AND ( "Artificial Intelligence"[Mesh] OR "artificial intelligence"[Title/Abstract] OR "machine learning"[Title/Abstract] OR "deep learning"[Title/Abstract] OR "neural network*"[Title/Abstract] OR "computer vision"[Title/Abstract] OR "computer-aided diagnosis"[Title/Abstract] OR "large language model*"[Title/Abstract] OR "vision-language model*"[Title/Abstract] OR multimodal[Title/Abstract] OR "multi-modal"[Title/Abstract] ) AND ( predict*[Title/Abstract] OR prognos*[Title/Abstract] OR "risk prediction"[Title/Abstract] OR "risk stratification"[Title/Abstract] OR "malignancy prediction"[Title/Abstract] OR "malignancy classification"[Title/Abstract] OR diagnos*[Title/Abstract] OR screening[Title/Abstract] ) AND ("2016/01/01"[Date - Publication] : "2026/12/31"[Date - Publication]) |
| IEEE Xplore ("All Metadata":"lung cancer" OR "All Metadata":"lung carcinoma" OR "All Metadata":"pulmonary cancer" OR "All Metadata":"lung neoplasm" OR "All Metadata":"pulmonary nodule" OR "All Metadata":"lung nodule") AND ("All Metadata":"computed tomography" OR "All Metadata":"low-dose computed tomography" OR "All Metadata":"low-dose CT" OR "All Metadata":LDCT OR "All Metadata":"chest CT" OR "All Metadata":radiomics OR "All Metadata":"CT imaging") AND ("All Metadata":"artificial intelligence" OR "All Metadata":"machine learning" OR "All Metadata":"deep learning" OR "All Metadata":"neural network" OR "All Metadata":"computer vision" OR "All Metadata":"large language model" OR "All Metadata":"vision-language model" OR "All Metadata":multimodal) AND ("All Metadata":prediction OR "All Metadata":prognosis OR "All Metadata":"risk prediction" OR "All Metadata":"risk stratification" OR "All Metadata":"malignancy prediction" OR "All Metadata":"malignancy classification" OR "All Metadata":diagnosis OR "All Metadata":screening) |
| ACM Digital Library [[All: "lung cancer"] OR [All: "lung carcinoma"] OR [All: "pulmonary cancer"] OR [All: "lung neoplasm"] OR [All: "pulmonary nodule"] OR [All: "lung nodule"]] AND [[All: "computed tomography"] OR [All: "low-dose computed tomography"] OR [All: "low-dose ct"] OR [All: ldct] OR [All: "chest ct"] OR [All: radiomics] OR [All: "ct imaging"]] AND [[All: "artificial intelligence"] OR [All: "machine learning"] OR [All: "deep learning"] OR [All: "neural network"] OR [All: "computer vision"] OR [All: "large language model"] OR [All: "vision-language model"] OR [All: multimodal]] AND [[All: prediction] OR [All: prognosis] OR [All: "risk prediction"] OR [All: "risk stratification"] OR [All: "malignancy prediction"] OR [All: "malignancy classification"] OR [All: diagnosis] OR [All: screening]] AND [E-Publication Date: (01/01/2016 TO 12/31/2026)] |
| Embase/Ovid ( exp lung cancer/ OR exp lung tumor/ OR exp non small cell lung cancer/ OR exp small cell lung cancer/ OR exp pulmonary nodule/ OR ((lung OR pulmonary) adj3 (cancer OR neoplasm OR tumour)).ti,ab,kw. OR (lung adj3 nodule" OR "computer vision" OR "large language model" OR multimodal OR "multi-modal").ti,ab,kw. ) AND ( (predict OR "risk prediction" OR "risk stratification" OR "malignancy prediction" OR "malignancy classification" OR diagnos$ OR screening).ti,ab,kw. ) AND ( 2016:2026 ).yr. |
| Item | Reported information | Status / qualification |
|---|---|---|
| Final search date | 21-Aug-2026 | Same date reported in the full manuscript. |
| Publication window | 2016–2026 | Represented in the query as PUBYEAR > 2015 and PUBYEAR < 2027 . |
| Database-specific retrieved records | Scopus: 6,963; PubMed: 3,184; Embase: 4,707; IEEE Xplore: 1,774; ACM: 288; total: 16,916 | Database-specific search strategies are reported in Supplementary Table S2 . |
| Language rule | Full text assessable under the review protocol: English or another language that could be reliably assessed by the review team. | Not described as an English-only database search filter. |
| Publication-type rule | Peer-reviewed primary empirical studies; eligible full conference papers allowed; reviews/surveys, editorials/commentaries, dataset-only publications, abstract-only records, retracted articles, preprints/non-peer-reviewed reports excluded. | From the predefined full-text criteria in the prior manuscript. |
| Deduplication | Hierarchical exact normalized DOI followed by exact normalized title; title match required normalized characters and no non-empty DOI/year conflict; transitive groups consolidated by Union–Find; bibliographically richest record retained; ambiguous conflicts retained for audit. | Conservative deduplication; 16,916 raw records reduced to 9,843. |
| Exclusion category | Count |
|---|---|
| Conference-abstract-only | 20 |
| Residual duplicate | 3 |
| Anonymous/inadequately attributable document | 0 |
| Document shorter than four pages | 10 |
| Non-peer-reviewed report | 5 |
| Unavailable full text | 12 |
| Record ID | Year | Study | Model/approach | Venue |
|---|---|---|---|---|
| REC_05652 | 2020 | Convolutional Neural Network ensembles for accurate lung nodule malignancy prediction 2 years in the future | CNN; ResNet; VGG; ensemble | Computers in Biology and Medicine |
| REC_04313 | 2022 | Deep Learning to Optimize Candidate Selection for Lung Cancer CT Screening: Advancing the 2021 USPSTF Recommendations | CNN | Radiology |
| REC_04101 | 2023 | Sybil: A Validated Deep Learning Model to Predict Future Lung Cancer Risk from a Single Low-Dose Chest Computed Tomography | CNN | Journal of Clinical Oncology |
| REC_01400 | 2025 | Radiomics for Dynamic Lung Cancer Risk Prediction in USPSTF-Ineligible Patients | LASSO/radiomics-based modelling | Cancers |
| Record ID | Year | Study | Model/approach | Venue |
|---|---|---|---|---|
| REC_01476 | 2025 | Significance of Image Reconstruction Parameters for Future Lung Cancer Risk Prediction Using Low-Dose Chest Computed Tomography and the Open-Access Sybil Algorithm | AI-based future-risk prediction | Investigative Radiology |
| REC_01674 | 2025 | External Testing of a Deep Learning Model for Lung Cancer Risk from Low-Dose Chest CT | Deep-learning risk model; external testing | Radiology |
| REC_01865 | 2025 | Deep learning-based lung cancer risk assessment using chest computed tomography images without pulmonary nodules mm | CNN; DenseNet; EfficientNet; U-Net/nnU-Net | Translational Lung Cancer Research |
| REC_02099 | 2025 | Predicting Future Lung Cancer Risk in Low-Dose CT Screening Patients with AI Tools | CNN; VGG | Proceedings of SPIE |
| Item | Reporting topic | Location/status |
|---|---|---|
| 1–4 | Title, abstract, rationale, objectives | Title/Abstract, Introduction, and five Review Questions. |
| 5–7 | Eligibility, information sources, search | Tables I – II ; five databases; final search 21 August 2026; Fig. . |
| 8–10 | Selection, collection, data items | Deduplication/screening/full-text Methods; role-aware extraction; Table III . |
| 11 | Study risk of bias | Completed for all 293 studies: QUADAS-3 v1.2 for 230 Detection studies and PROBAST+AI (2025) for 63 Risk/Other studies. |
| 12–13 | Effect/synthesis methods | No pooled clinical effect measure; descriptive prevalence, semantic/network analyses, permutation and matched resampling specified. |
| 14–15 | Reporting bias/certainty | No pooled publication-bias or GRADE claim; selection and evidence limitations are explicitly reported. |