Circumferential Resection Margin as Predictor of Nonclinical Complete Response in Nonoperative Management of Rectal Cancer

Re I. Chin, Joshua P. Schiff, Anup S. Shetty, Katrina S. Pedersen, Olivia Aranha, Yi Huang, Steven R. Hunt, Sean C. Glasgow, Benjamin R. Tan, Paul E. Wise, Matthew L. Silviera, Radhika K. Smith, Rama Suresh, Kathleen Byrnes, Pamela P. Samson, Shahed N. Badiyan, Lauren E. Henke, Matthew G. Mutch, Hyun Kim

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

BACKGROUND: Short-course radiation therapy and consolidation chemotherapy with nonoperative intent has emerged as a novel treatment paradigm for patients with rectal cancer, but there are no data on the predictors of clinical complete response. OBJECTIVE: Evaluate the predictors of clinical complete response and survival. DESIGN: Retrospective cohort. SETTINGS: National Cancer Institute-designated cancer center. PATIENTS: Patients with stage I to III rectal adenocarcinoma treated between January 2018 and May 2019 (n = 86). INTERVENTIONS: Short-course radiation therapy followed by consolidation chemotherapy. MAIN OUTCOME MEASURES: Logistic regression was performed to assess for predictors of clinical complete response. The end points included local regrowth-free survival, regional control, distant metastasis-free survival, and overall survival. RESULTS: A positive (+) circumferential resection margin by MRI at diagnosis was a significant predictor of nonclinical complete response (OR: 4.1, p = 0.009) when adjusting for CEA level and primary tumor size. Compared to patients with a negative (-) pathologic circumferential resection margin, patients with a positive (+) pathologic circumferential resection margin had inferior local regrowth-free survival (29% vs 87%, p < 0.001), regional control (57% vs 94%, p < 0.001), distant metastasis-free survival (43% vs 95%, p < 0.001), and overall survival (86% vs 95%, p < 0.001) at 2 years. However, the (+) and (-) circumferential resection margin by MRI subgroups in patients who had a clinical complete response both had similar regional control, distant metastasis-free survival, and overall survival of more than 90% at 2 years. LIMITATIONS: Retrospective design, modest sample size, short follow-up, and the heterogeneity of treatments. CONCLUSIONS: Circumferential resection margin involvement by MRI at diagnosis is a strong predictor of nonclinical complete response. However, patients who achieve a clinical complete response after short-course radiation therapy and consolidation chemotherapy with nonoperative intent have excellent clinical outcomes regardless of the initial circumferential resection margin status.

Original languageEnglish
Pages (from-to)973-982
Number of pages10
JournalDiseases of the Colon and Rectum
Volume66
Issue number7
DOIs
StatePublished - Jul 2023

Keywords

  • Circumferential resection margin
  • Clinical complete response
  • Nonoperative management
  • Rectal cancer
  • Short-course radiation therapy

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