In this particular paper, the authors add their institutions experience to the literature regarding the outcomes of patients diagnosed with cystic clear cell renal cell carcinoma (ccRCC), defined as multilocular cystic renal neoplasms of low malignant potential or ccRCC with cystic change, which comprise less than 5% of renal cortical neoplasms and have been associated with a favorable prognosis in small retrospective studies.3,4
The authors identified 3,865 patients treated with radical or partial nephrectomy for unilateral, sporadic clear cell RCC (ccRCC) between 1970 and 2010. One urologic pathologist re-reviewed all pathologic slides, blinded to patient outcome. Cancer-specific survival (CSS) was estimated using the Kaplan-Meier method and compared between those with and without cystic ccRCC using log-rank tests.
Of their large series, only 158 of 3,865 (4%) patients had cystic ccRCC. Compared to patients with non-cystic ccRCC, patients with cystic ccRCC were younger (median 58 vs. 63 years, p<0.001), were more likely to have radiographic evidence of cystic structures (60% vs. 17%, p<0.001), were less likely to have distant metastases at surgery (0% vs. 14%, p<0.001), and had smaller tumors (median 3.0 vs. 6.0cm, p<0.001) that were less likely to contain coagulative tumor necrosis (1% vs. 29%, p<0.001) or sarcomatoid differentiation (0% vs. 5%, p=0.006). Importantly, they were generally lower pT-stage compared to non-cystic RCC patients. Fuhrman grade was not reported. With a median follow-up for survivors of 10.5 years (IQR 7.3-14.9), 63 patients with cystic ccRCC died at a median of 7.7 years after surgery (IQR 3.8-11.9). However, only one patient died from RCC after developing metastases 22 years after the initial surgery. CSS rates at 25 years following surgery were significantly better for cystic ccRCC compared to non-cystic ccRCC (88% vs. 52%, p<0.001), even among the subset of pT1, pNX/0, M0 patients (100% vs. 83%, p=0.001).
These results validate findings from both institutional series and population-level analyses that have previously been published.
Limitations / Discussion Points:
1. All of these patients were surgically treated. More recent series have begun to examine the role of non-operative management for cystic renal masses, as these appear to have relatively indolent clinical courses.
1. Natural History of Complex Renal Cysts: Clinical Evidence Supporting Active Surveillance. Chandrasekar T, Ahmad AE, Fadaak K, Jhaveri K, Bhatt JR, Jewett MAS, Finelli A. J Urol. 2017 Sep 20. pii: S0022-5347(17)77564-7. doi: 10.1016/j.juro.2017.09.078. [Epub ahead of print]
2. Bosniak Classification for Complex Renal Cysts Reevaluated: A Systematic Review. Schoots IG, Zaccai K, Hunink MG, Verhagen PCMS. J Urol. 2017 Jul;198(1):12-21. doi: 10.1016/j.juro.2016.09.160. Epub 2017 Mar 9. Review.
3. Winters BR, Gore JL, Holt SK, et al. Cystic renal cell carcinoma carries an excellent prognosis regardless of tumor size. Urol Oncol. 2015 Dec;33(12):505.e9-13. doi: 10.1016/j.urolonc.2015.07.017. Epub 2015 Aug 28.
4. Bhatt JR, Jewett MA, Richard PO, Kawaguchi S, Timilshina N, Evans A, Alibhai S, Finelli A. Multilocular Cystic Renal Cell Carcinoma: Pathological T Staging Makes No Difference to Favorable Outcomes and Should be Reclassified. J Urol. 2016 Nov;196(5):1350-1355. doi: 10.1016/j.juro.2016.05.118. Epub 2016 Jun 21.
Presented by: Mary Elizabeth Westerman, MD
Co-Authors: Vidit Sharma MD¹, Christine M. Lohse MS², Stephen A. Boorjian MD¹, Bradley C. Leibovich MD¹, John C. Cheville MD³ and R. Houston Thompson MD¹
Affiliation: ¹Mayo Clinic Department of Urology, Rochester Minnesota; ²Mayo Clinic Department of Health Sciences Research, Rochester Minnesota; ³Mayo Clinic Department of Pathology, Rochester Minnesota
Written by: Thenappan Chandrasekar, MD, Clinical Fellow, University of Toronto, twitter: @tchandra_uromd at the 18th Annual Meeting of the Society of Urologic Oncology, November 20-December 1, 2017 – Washington, DC