• Confirmed history of previous radically or curative-intent treated solid organ cancer within 10 years of new index CT thoracic scan demonstrating a new pulmonary nodule and either of the following:

‣ Biopsy confirming previous malignancy with MDT consensus and successful cancer resolution/remission following anti-cancer treatment on interval imaging or blood assay analysis

⁃ Where biopsy was not possible/confirmed for previous malignancy, MDT consensus outcome confirming cancer (+/- calculated Herder score \>80% if applicable) and decision to treat as malignancy with subsequent resolution/remission following anti-cancer treatment on interval imaging or blood assay analysis

• Radical treatment for previous cancer defined as either of the following:

‣ Surgical resection

⁃ Radical radiotherapy or stereotactic beam radiotherapy

⁃ Radical chemotherapy

⁃ Radical chemo-radiotherapy

⁃ Multi-modality treatment with any of the above

• New pulmonary nodule ground truth known

‣ Scan data showing 2-year stability (based on diameter or volumetry) or resolution in cases of benign disease

⁃ Scan data showing progressive nodule enlargement or increase in nodule number on interval imaging with MDT consensus (+/- PET with Herder score \>80% if applicable) determining metastatic disease or new primary malignancy

⁃ Biopsy sampling confirming benign disease or malignancy and in cases of malignancy, metastasis or new primary lung cancer

• CT scan slice thickness ≤ 2.5mm

• Nodule size ≥ 5mm