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A Nomogram to Predict Lymph Node Positivity Following Neoadjuvant Chemoradiation in Locally Advanced Rectal Cancer

Newton, Andrew D. M.D.; Li, Jiaqi M.S.; Jeganathan, Arjun N. M.D.; Mahmoud, Najjia N. M.D.; Epstein, Andrew J. Ph.D., M.P.P.; Paulson, E. Carter M.D., M.S.C.E.

Diseases of the Colon & Rectum: August 2016 - Volume 59 - Issue 8 - p 710–717
doi: 10.1097/DCR.0000000000000638
Original Contributions: Colorectal/Anal Neoplasia
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BACKGROUND: Patients with locally advanced rectal cancer typically receive neoadjuvant chemoradiation followed by total mesorectal excision. Other treatment approaches, including transanal techniques and close surveillance, are becoming increasingly common following positive responses to chemoradiation. Lack of pathologic lymph node staging is one major disadvantage of these novel strategies.

OBJECTIVE: The purposes of this study were to determine clinicopathologic factors associated with positive lymph nodes following neoadjuvant chemoradiation for rectal cancer and to create a nomogram using these factors to predict rates of lymph node positivity.

DESIGN: This is a retrospective cohort analysis.

SETTINGS: This study used the National Cancer Database.

PATIENTS: Patients aged 18 to 90 with clinical stage T3/T4, N0, M0 or Tany, N1-2, M0 adenocarcinoma of the rectum who underwent neoadjuvant chemoradiation before total mesorectal excision from 2010 to 2012 were identified.

MAIN OUTCOME MEASURES: The primary outcome measure was lymph node positivity after neoadjuvant chemoradiation for locally advanced rectal cancer. Bivariate and multivariate analyses were used to determine the associations of clinicopathologic variables with lymph node positivity.

RESULTS: Eight thousand nine hundred eighty-four patients were included. Young age, lower Charlson score, mucinous histology, poorly differentiated and undifferentiated tumors, the presence of lymphovascular invasion, elevated CEA level, and clinical lymph node positivity were significantly predictive of pathologic lymph node positivity following neoadjuvant chemoradiation. The predictive accuracy of the nomogram is 70.9%, with a c index of 0.71. There was minimal deviation between the predicted and observed outcomes.

LIMITATIONS: This study is retrospective, and it cannot be determined when in the course of treatment the data were collected.

CONCLUSIONS: We created a nomogram to predict lymph node positivity following neoadjuvant chemoradiation for locally advanced rectal cancer that can serve as a valuable complement to imaging to aid clinicians and patients in determining the best treatment strategy.

1 Department of Surgery, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania

2 Department of Biostatistics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania

3 Division of General Internal Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania

4 Department of Surgery, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, Pennsylvania

Financial Disclosures: None reported.

Poster presentation at the annual meeting of the American Society of Colon and Rectal Surgeons in Los Angeles, CA, April 30 to May 4, 2016.

Correspondence: Andrew D. Newton, M.D., Hospital of the University of Pennsylvania, Department of Surgery, 3400 Spruce Street, 4 Maloney, Philadelphia, PA 19104. E-mail: Andrew.Newton@uphs.upenn.edu

© 2016 The American Society of Colon and Rectal Surgeons