Pathological evaluation of lymph nodes in oesophagogastric cancer resection specimens is largely restricted to the detection of metastatic deposits and determination of nodal stage. Once a lymph node is deemed tumour-free, its morphology is rarely assessed systematically nor is it routinely reported. Yet tumour-draining lymph nodes are key sites of antigen presentation, immune activation, immune suppression, and the generation of antitumour responses. As such, tumour-free lymph nodes may contain important information about host–tumour interactions that is currently overlooked. We have demonstrated that the size of tumour-free lymph nodes is associated with survival in patients with oesophagogastric cancer, suggesting that biologically relevant information exists beyond conventional nodal staging.
Despite increasing interest in the tumour immune microenvironment, little is known about the biological and clinical significance of immune reaction patterns in tumour-free regional lymph nodes. It remains unclear whether features such as follicular hyperplasia, paracortical expansion, sinus histiocytosis, or lymphocyte depletion reflect effective antitumour immunity, treatment response, risk of recurrence, or susceptibility to metastatic spread. The effects of neoadjuvant chemotherapy, chemoradiotherapy, and immunotherapy on lymph node architecture are also poorly understood.
Thus, tumour-free lymph nodes represent an underutilised and readily available tissue resource obtained routinely during oncological resection. Unlike many emerging biomarkers, assessment of nodal reaction patterns requires no additional tissue acquisition and could potentially be incorporated into standard histopathological workflows. If clinically relevant associations are validated, these features may complement TNM staging and improve stratification of patients for treatment.
This lecture will review current approaches to lymph node assessment in oesophagogastric cancer, examine the role of tumour-draining lymph nodes in cancer immunity, and discuss the spectrum of lymph node reaction patterns. Results from our own ongoing studies will be presented, highlighting key knowledge gaps and exploring why systematic evaluation of tumour-free lymph nodes may represent the next frontier in pathological assessment.