Along those same lines, there is increased interest in nephron-sparing management of mRCC, particularly when the primary disease is relatively small. While not that common, as larger masses are more often associated with metastatic disease and less commonly technically able to be managed with partial nephrectomy, there are a subset of patients with small primary tumors and metastatic disease.
In this abstract, the authors assess the role for NSS (nephron sparing surgery) in patients with mRCC. To do so, they utilized the SEER dataset, a well established dataset representing approximately 30% of all cancer diagnoses in the United States. They excluded patients with RCC diagnosis at autopsy, multiple primary malignancies, and incomplete pathological or surgical data. They looked at a very broad time frame (1973-2013) – the full extent of the dataset – however, it should be noted that capture earlier in the SEER dataset was less complete!
They identified 18,443 patients identified with mRCC – assuming they were metastatic at the time of diagnosis, though this was not specifically stated in the abstract. 57% never received cytoreductive treatment.
In terms of demographics, 83.6% were white and 67.9% were male. Mean age was 62.7 years. Tumor laterality was 8408 right, 8998 left, 197 bilateral and 840 unspecified. 31% were poorly differentiated while only 2.2% were well differentiated.
The cytoreductive intervention was performed in 7884 of these patients: 7598 radical nephrectomy, 208 partial nephrectomy and 78 ablation. These were presumed to be cytoreductive, as patients were cM1 and had some intervention done.
Overall and cancer specific survival for the entire cohort and each treatment group was assessed. As expected, patients with mRCC had relatively poor prognosis as a whole – 4.4% 10-year OS and 7.1% 10-year CSS. However, when stratified, the patients who received no intervention did the worse, while patients who underwent NSS did the best (21.7% 10-year OS and 36.8% 10-year CSS). Patients who underwent ablation did not have 10 or 15-year follow-up but did worse than NSS patients at the 5-year mark.
In a subgroup analysis of patients with cT1 tumors (n=1590), 578 had cytoreductive therapy: 499 radical nephrectomy, 63 partial nephrectomy and 16 ablations. More importantly, most had no intervention – likely because metastatic burden exceeded primary disease. In this group, patients who underwent partial nephrectomy had improved overall and cancer specific survival when compared to patients who underwent ablation or radical nephrectomy (p=0.0001).
While these results are thought provoking, they likely reflect a strong selection bias – which unfortunately limits it utility moving forward. Patients selected for NSS likely had low volume disease, to begin with. Patients selected for ablation likely had a small lesion and were too unhealthy for surgery. Patients receiving no intervention likely were unfit for any intervention. As such, the findings reflect patient selection rather than the benefit of therapy.
Also, while encompassing such a large time frame, the authors muddy the picture by including different eras of management – both systemic therapy and surgical management have changed drastically in these eras, and the decision for NSS and technical feasibility have changed. Hence, the generalizability of their results is limited.
However, while current dogma recommends treating the primary if it represents the bulk of disease, their results may encourage prospective evaluation of NSS or radical nephrectomy for cT1 disease.
Presented by: Lukas Hockman, University of Missouri, Columbia, Missouri
Co-Authors: Logan McGuffey, Aaron Dwan, Naveen Pokala, Columbia, MO
Written by: Thenappan Chandrasekar, MD, Clinical Fellow, University of Toronto, @tchandra_uromd at the 2018 AUA Annual Meeting - May 18 - 21, 2018 – San Francisco, CA USA