Maxine Sun and Quoc-Dien Trinh contributed equally to this study.
Extent of lymphadenectomy does not improve the survival of patients with renal cell carcinoma and nodal metastases: biases associated with the handling of missing data
Article first published online: 12 MAR 2013
© 2013 BJU International
Volume 113, Issue 1, pages 36–42, January 2014
How to Cite
Sun, M., Trinh, Q.-D., Bianchi, M., Hansen, J., Abdollah, F., Tian, Z., Shariat, S. F., Montorsi, F., Perrotte, P. and Karakiewicz, P. I. (2014), Extent of lymphadenectomy does not improve the survival of patients with renal cell carcinoma and nodal metastases: biases associated with the handling of missing data. BJU International, 113: 36–42. doi: 10.1111/j.1464-410X.2012.11693.x
- Issue published online: 13 DEC 2013
- Article first published online: 12 MAR 2013
- University of Montreal Health Centre Urology Specialists
- Fonds de la Recherche en Santé du Québec
- University of Montreal Department of Surgery
- University of Montreal Health Centre (CHUM) Foundation
- lymph node dissection;
- renal cell carcinoma;
What's known on the subject? and What does the study add?
- A recent population-based analysis suggested a potential survival benefit with respect to performing lymph node dissection at nephrectomy in node-positive patients with RCC.
- The findings of the present study failed to corroborate the association of a survival benefit with the performance of lymph node dissection at nephrectomy.
- Previous studies showed no survival benefit with respect to performing lymph node dissection (LND) at nephrectomy, whereas a recent population-based analysis suggested otherwise, although the latter relied on imputation. To reconcile the findings of that study by critically evaluating the handling of missing data.
Patients and Methods
- Study participants comprised patients diagnosed with non-metastatic renal cell carcinoma (RCC) of all stages who underwent LND at nephrectomy (n = 10 596).
- Multivariable Cox regression models were performed to predict cancer-specific mortality (CSM), where the primary variable of interest was the extent of LND.
- To examine differences in approaches with respect to handling missing data, separate analyses were performed: (i) imputed population; (ii) exclusion of patients with missing data; and (iii) inclusion of patients with missing data as a sub-category.
- Overall, 2916 (28%) patients had missing tumour grade.
- In multivariable analyses, our findings showed that increasing the extent of LND was associated with a significant protective effect on CSM in patients with pN1 after imputation (hazard ratio [HR], 0.82; P = 0.04).
- By contrast, the extent of LND was no longer significantly associated with a lower risk of CSM after excluding patients with a missing tumour grade (HR, 0.83; P = 0.1) or when including patients with missing tumour grade as a sub-category (HR, 0.82; P = 0.05).
- The findings of the present study failed to corroborate the association of a survival benefit with increasing extent of LND at nephrectomy.
- The different methodologies employed to account for missing data may introduce important biases.
- Such considerations are non-negligible with respect to the interpretation of results for investigators who rely on administrative cohorts.