Background: Renal cell carcinoma (RCC) with inferior vena cava (IVC) tumor thrombus carries a poor prognosis and presents complex medical management to urologists. Long-term data examining RCC with IVC tumor thrombus is sparse. Specifically, markers predicting cancer-specific survival are lacking. Recently, immune cell markers in cancer, such as neutrophils, lymphocytes, and monocytes, have come into focus. These cell counts and/or ratios may provide a window into cancer-specific outcomes. The purpose of this study was to examine the use of immune cell ratios in patients with RCC and IVC tumor thrombus to predict survival outcomes through a collaboration project across North and South America. Methods: Patients were included in this study if they had a diagnosis of RCC with IVC tumor thrombus and underwent nephrectomy with IVC thrombectomy for their RCC. Data was reviewed and entered into a multi-institutional/continental database. Complete blood counts taken as close to the date prior to/date of surgery were used to calculate immune cell ratios. Neutrophil to (/) lymphocyte ratios were done by dividing patients’ neutrophil cell count by their lymphocyte count. Monocyte/lymphocyte ratios were calculated in the same manner. Independent samples t-test was used to test for significance in cause of death post-operatively (RCC versus non-RCC cause) based on immune cell ratio. Results: There were 107 patients included in the study with long-term follow-up data (Mean: 2.6 years; Range: 0-16-years). Of all patients, 43/107 died by the end of the study, with 31/43 (72.1%) dying due to RCC and 12/43 (27.9%) from other causes. No difference existed in neutrophil/lymphocyte ratios based on cause of death (p=0.260). Monocyte/lymphocyte ratios were significantly lower in those who died from RCC relative to another cause (p=0.035). Conclusions: Immune cell ratios may have a role in predicting death from RCC. In our study, monocyte/lymphocyte ratios were significantly lower in patients who died from RCC compared to death from other reasons. Our results stem from a multi-continental/institutional study, and thus hold clinical utility as an increased focus is turned towards including diverse populations in research. Urologists may consider monocyte/lymphocyte ratios in the future when managing patients with RCC and an IVC thrombus.

Note: P-values are comparing immune cell ratios based on cause of death. Standard deviations are in parentheses.