P11.64.a treatment strategies before the diagnosis of brain metastasis in patients with renal cell cancer (rcc)

Abstract BACKGROUND Metastatic renal cell cancer (mRCC) is known for its variable disease course and can be categorized according to the International Metastatic RCC Database Consortium (IMDC) criteria. As patients with mRCC who have a favorable IMDC score and/or a low tumor burden usually have an indolent disease course, watchful waiting is often considered in daily clinical practice. However, it is unknown whether watchful waiting impacts the development of brain metastasis (BM). Therefore, we investigated variables that may affect the interval between first diagnosis of mRCC and BM (BM-free interval) in patients with RCC and BM. MATERIAL AND METHODS A single-center, retrospective cohort study was performed at the Erasmus MC Cancer Institute (Rotterdam, the Netherlands). All consecutive patients with a diagnosis of RCC and BM between 01-01-2011 and 31-07-2022 were included. The primary outcome was the BM-free interval. Secondary outcomes were intracranial progression-free survival (iPFS), progression-free survival (PFS) and overall survival (OS), since diagnosis of BM. Subgroups included patients with and without systemic treatment prior to the diagnosis of BM. Kaplan-Meier (Logrank test) and Cox Proportional Hazards Model (Likelihood ratio test) analyses were performed with significance considered at p-values <0.05. RESULTS A total of 46 patients with RCC and BM were included; 80% was male and 89.1% had a clear cell RCC subtype. In 84.8% of patients, BMs were diagnosed metachronous (>1 month) after the diagnosis of extracranial metastasis (ECM) and 80.4% of patients had symptomatic BM at BM diagnosis. After the diagnosis of BM, the median iPFS was 7.6 (IQR 3.5-12.2) months, the median PFS was 3.7 (IQR 2.3-8.7) months and the median OS was 10.1 (IQR 5.1-22.8) months. Prior to the diagnosis of BM, 25 (54.3%) patients had received systemic therapy, whereas 21 (45.7%) patients were treatment naïve. The median BM-free interval was 22.3 (IQR 5.7-46.7) months. The median BM-free interval was significantly shorter for treatment naïve patients (6.8 [IQR 1.0-7.0] months) as compared to patients who received previous systemic therapy (29.0 [IQR 12.6-57.0]; p=0.02). In multivariate analysis, a longer BM-free interval was significantly associated with nephrectomy (HR 0.10 [95%CI 0.03-0.31]) and systemic treatment prior to BM diagnosis (HR 0.10 [95%CI 0.03-0.30]). CONCLUSION In this cohort of patients with RCC BM, patients who had not received systemic treatment for ECM were earlier diagnosed with BM than patients who had received prior systemic treatment. Although the retrospective nature of this small selective cohort is a limitation, these results indicate that watchful waiting should be carefully considered for patients with mRCC.