abstract:
External validation of the pathological nodal staging score in upper tract urothelial carcinoma: A population-based study - Urologic Oncology: Seminars and Original Investigations
Objectives
To
externally validate our previously developed pathological nodal staging
model (pNSS) that allows quantification of the
likelihood that a patient
with pathologic node-negative status has, indeed, no lymph node
metastasis (LNM).
Patients and methods
We
analyzed data from
2,768 patients treated with radical
nephroureterectomy (RNU) and lymph node dissection (LND) using the
Surveillance, Epidemiology, and End Results database from 1988 to 2010.
We estimated the sensitivity of pathologic nodal staging using a
beta-binomial model and developed a new pNSS. Then, we compared these
findings with those of the initial cohort.
Results
The
mean and median numbers of lymph node (LN) removed were 5 and 2,
respectively (interquartile range = 5) in the validation cohort, though
66.5% of the patients (
n = 1814) were pN0. Similar to the
development cohort, the probability of missing a LNM decreased as the
number of nodes examined increased in the validation cohort.
If only a
single node was examined, 35% of patients would be misclassified as pN0
while harboring LNM. Even when 5 nodes were examined, 8% would be
misclassified. The probability of having a positive node increased with
advancing pathological T stage in both the cohorts. Patients with
pT0-Ta-Tis-T1 disease in both cohorts would have more than a 95% chance
of a correct pathologic nodal staging with 2 examined nodes. However, if
a patient has pT3–T4 disease, more than 12 examined LNs are needed to
reach 95% accuracy.
Conclusions
We
confirmed that the number of examined nodes needed for adequate staging
depends on pT category. We externally validated our previous pNSS in a
population-based database, which could help in the clinical
decision-making regarding adjuvant chemotherapy administration.
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