Lymph Node Ratio Is Less Prognostic in Melanoma When Minimum Node Retrieval Thresholds Are Not Met.
Mark A Healy1,2, Evan Reynolds3,4, Mousumi Banerjee3,4
1Department of Surgery, University of Michigan, Ann Arbor, MI, USA. healym@umich.edu.
Annals of Surgical Oncology
|August 7, 2016
Summary
Lymph node ratio (LNR) does not offer better melanoma prognostication than positive or examined node counts. Its predictive value decreases when fewer than ten nodes are examined for ALND or five for ILND.
Area of Science:
- Oncology
- Surgical Pathology
- Cancer Prognostics
Background:
- Lymph node ratio (LNR) is proposed for melanoma prognostication to address low lymph node counts.
- The comparative prognostic value of LNR versus total positive and examined lymph node counts remains unclear.
- The impact of minimum examined lymph node thresholds on LNR's prognostic accuracy requires investigation.
Purpose of the Study:
- To evaluate if LNR offers superior prognostication compared to the total counts of positive and examined lymph nodes in melanoma patients.
- To determine if the prognostic value of LNR is influenced by minimum thresholds for the number of lymph nodes examined.
Main Methods:
- Utilized the National Cancer Data Base Participant User File to identify 74,692 incident melanoma cases with nodal dissection (2000-2006).
- Compared the predictive ability (Harrell's C) of LNR against counts of examined and positive nodes.
- Stratified analysis based on examined node thresholds: ≥10 versus <10 for axillary lymph node dissection (ALND) and ≥5 versus <5 for inguinal lymph node dissection (ILND).
Main Results:
- Overall, LNR (Harrell's C=0.628) showed no significant prognostic superiority over examined (C=0.625) or positive node counts (C=0.625).
- For ALND, LNR's prognostic value was higher with ≥10 nodes examined (C=0.626) compared to <10 nodes (C=0.554).
- For ILND, LNR's prognostic value was higher with ≥5 nodes examined (C=0.679) compared to <5 nodes (C=0.601).
Conclusions:
- Lymph node ratio (LNR) does not provide superior prognostication for melanoma compared to the total counts of examined and positive lymph nodes.
- The prognostic accuracy of LNR is diminished when minimum lymph node retrieval thresholds are not met, highlighting the importance of adequate nodal sampling.
