Nodal stage migration and prognosis in anal cancer: a systematic review, meta-regression, and simulation study

摘要

Background In patients with squamous cell carcinoma of the anus (SCCA), lymph node positivity (LNP) indicates poor prognosis for survival and is central to radiotherapy planning. Over the past three decades, LNP proportion has increased, mainly reflecting enhanced detection with newer imaging modalities; a process known as nodal stage migration. If accompanied by constant T stage distributions, prognosis for both lymph node-positive and lymph node-negative groups may improve without any increase in overall survival for individual patients; a paradox termed the Will Rogers phenomenon. Here, we aim to systematically evaluate the impact of nodal stage migration on survival in SCCA and address a novel hypothesis that this phenomenon results in reduced prognostic discrimination.