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

  • 0Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, NIHR Manchester Biomedical Research Centre, Manchester Academic Health Science Centre, Manchester, UK.
The Lancet. Oncology +

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August 14, 2017

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August 14, 2017

View abstract on PubMed

Summary

This summary is machine-generated.

Nodal stage migration in anal cancer has increased lymph node positivity (LNP) detection. This phenomenon may paradoxically reduce prognostic discrimination, potentially leading to overtreatment due to misclassified disease stages.

Area Of Science

  • Oncology
  • Radiotherapy
  • Cancer Staging

Background

  • Squamous cell carcinoma of the anus (SCCA) prognosis is heavily influenced by lymph node positivity (LNP).
  • Nodal stage migration, an increase in LNP detection due to advanced imaging, has been observed over three decades.
  • This migration may create a paradox where survival appears improved without actual patient benefit, known as the Will Rogers phenomenon.

Purpose Of The Study

  • To systematically evaluate the impact of nodal stage migration on survival in SCCA.
  • To test the hypothesis that nodal stage migration leads to reduced prognostic discrimination.

Main Methods

  • A systematic review and meta-regression of randomized trials and observational studies on SCCA patients treated with radiotherapy or chemoradiotherapy (1970-2016).
  • Analysis of changes in LNP proportions over time and their association with overall survival and prognostic discrimination.
  • Simulation of varying true LNP proportions and misclassification levels to assess prognostic discrimination.

Main Results

  • Identified 62 studies with 10,569 patients; LNP proportions increased from 15.3% in 1980 to 37.1% in 2012 (p<0.0001).
  • Increasing LNP was associated with improved survival in both node-positive and node-negative groups, with constant T stage distributions.
  • Hazard ratios for overall survival decreased significantly as LNP increased, suggesting reduced prognostic discrimination.

Conclusions

  • Nodal stage migration in SCCA can lead to reduced prognostic discrimination, a phenomenon termed "reduced prognostic discrimination."
  • Observed LNP proportions exceeding 30% in recent studies may represent overestimation due to misclassification.
  • Advancements in staging technologies may misclassify disease, potentially leading to overtreatment in anal cancer management.