  Human readers or radiologists routinely perform full-body multi-organ
multi-disease detection and diagnosis in clinical practice, while most medical
AI systems are built to focus on single organs with a narrow list of a few
diseases. This might severely limit AI's clinical adoption. A certain number of
AI models need to be assembled non-trivially to match the diagnostic process of
a human reading a CT scan. In this paper, we construct a Unified Tumor
Transformer (CancerUniT) model to jointly detect tumor existence & location and
diagnose tumor characteristics for eight major cancers in CT scans. CancerUniT
is a query-based Mask Transformer model with the output of multi-tumor
prediction. We decouple the object queries into organ queries, tumor detection
queries and tumor diagnosis queries, and further establish hierarchical
relationships among the three groups. This clinically-inspired architecture
effectively assists inter- and intra-organ representation learning of tumors
and facilitates the resolution of these complex, anatomically related
multi-organ cancer image reading tasks. CancerUniT is trained end-to-end using
a curated large-scale CT images of 10,042 patients including eight major types
of cancers and occurring non-cancer tumors (all are pathology-confirmed with 3D
tumor masks annotated by radiologists). On the test set of 631 patients,
CancerUniT has demonstrated strong performance under a set of clinically
relevant evaluation metrics, substantially outperforming both multi-disease
methods and an assembly of eight single-organ expert models in tumor detection,
segmentation, and diagnosis. This moves one step closer towards a universal
high performance cancer screening tool.
