Optimal Lymph Node Yield for Survival Prediction in Rectal Cancer Patients After Neoadjuvant Therapy

Abstract

Purpose

A lymph node (LN) yield ≥12 is required to for accurate determination of nodal status for colorectal cancer but cannot always be achieved after neoadjuvant therapy. This study aims to determine the difference in LN yield from rectal cancer patients treated with and without neoadjuvant therapy and the effects of specific LN yields on survival.

Patients and Methods

The study cohort included a total of 4344 rectal cancer patients treated between January 2007 and December 2015, 2260 (52.03%) of whom received neoadjuvant therapy. Data were retrieved from the Taiwan nationwide cancer registry database. The minimum acceptable LN yield below 12 was investigated using the maximum area under the ROC curve.

Results

The median LN yield was 12 (8–17) for patients who received neoadjuvant therapy and 17 (13–24) for those who did not. The recommended LN yield ≥12 was achieved in 82.73% of patients without and 57.96% of those with neoadjuvant therapy (p < 0.0001). Patients with LN yield ≥12 had a higher OS probability than did those with LN <12 (OR, 1.33; 95% CI, 1.06–1.66; p = 0.0124). However, the predictive accuracy for survival was greater for LN yield ≥10 (AUC, 0.7767) than cut-offs of 12, 8, or 6, especially in patients with pathologically-negative nodes (AUC, 0.7660).

Conclusion

Neoadjuvant therapy significantly reduces the LN yield in subsequent surgery. A lower yield (LN ≥ 10) may be adequate for nodal evaluation in rectal cancer patients after neoadjuvant therapy.

Keywords:

• rectal cancer
• neoadjuvant therapy
• lymph node yield
• quality
• survival

Acknowledgments

We acknowledge the support provided by the following grants: (1) Health and Welfare surcharge on tobacco products (MOHW110-TDU-B-212-144020, WanFang Hospital, Chi-Mei Medical Center, and Hualien Tzu-Chi Hospital Joing Cancer Center Grant-Focus on Colon Cancer Research); (2) CMFHR11011 and 110CM-TMU-01 from the Chi Mei Medical center. We are also grateful to the Health Data Science Center, National Cheng Kung University Hospital for providing administrative and technical support.

Abbreviations

LN, lymph node; AJCC, American Joint Committee on Cancer; CAP, Union for International Cancer Control, and College of American Pathologists; TME, total mesorectal excision; ROC, receiver operating characteristic; TCR, Taiwan Cancer Registry; NHIRD, National Health Insurance Research database; ICD-O-3, International Classification of Diseases for Oncology, 3rd Edition; CCI, Charlson comorbidity index; OS, overall survival; rN, positive lymph nodes; LODDS, log odds of positive lymph nodes.

Ethics Approval and Informed Consent

This study was conducted according to the guidelines of the Declaration of Helsinki and approved by the Ethics Committee of the Institutional Review Board of the Chi Mei Medical Center (IRB: CMFHR10707–012). This study had a non-interventional retrospective design; no human subjects or personally identifying information were used, and all data were analyzed anonymously. Thus, informed consent was waived by the IRB.

Disclosure

The authors have no conflicts of interest.