The Huchang-Barrier framework: an integrative perspective on the spatial features of the tumor invasive front

The tumor invasive front is a critical interface for tumor-host interactions that impacts patient prognosis. Although the tumor-node-metastasis (TNM) staging system and single-parameter assessments such as tumor budding, T-cell density, tertiary lymphoid structures (TLS), and stromal features provide important prognostic information, they capture only partial aspects of this spatially organized tumor-host interface. Inspired by the traditional Chinese medicine concept of "Huchang", used here as a metaphorical descriptor of host-protective organization at the tumor boundary, and informed by recent advances in spatial immunology, we propose the Huchang-Barrier (HB) framework. HB conceptualizes the invasive front as a dynamic tumor-host interface whose biological state is determined by the balance between tumor invasive burden and host physical/tissue and spatial immune barriers. Unlike fixed single-marker scores or tumor-type-specific microenvironmental indices, HB integrates three conserved functional elements while allowing cancer-adapted readouts, thereby providing a modular framework for evaluating the invasion-barrier balance at the invasive front. To improve operability, we outline a two-tier assessment strategy and provide a minimal executable HB-Standard example in resected non-small cell lung cancer (NSCLC). The HB framework is proposed as a hypothesis-generating spatial pathology model that requires retrospective calibration, independent validation, and prospective testing before clinical implementation.