Kidney cancer metastases to breast and other genitourinary (GU) organs: A pooled analysis.

Abstract

401 Background: As the number of kidney cancer survivors increases, the appearance of second malignancies and unusual metastatic patterns is increasing. We performed a pooled analysis to assess the clinicopathologic findings, treatment, and outcomes of cases involving breast and GU organs. Methods: Pooled analysis of published case reports and case series of renal cell carcinoma (RCC) metastasis to breast and genitourinary (GU) organs, including four cases from our institution. Parameters were compared between GU organ cohorts using a one-way ANOVA test and subgroup analysis. Results: 127 patients with GU metastasis of RCC were analyzed. The overall mean age was 61.2 years (Range: 14-92). GU organs with reported metastasis included 24 to testis (18.9%), 18 to penis (14.2%), 18 to breast (14.2%), 17 to vagina (13.4%), 17 to bladder (13.4%), 14 to ovary (11%), 7 to prostate (5.5%), and 6 to urethra (4.7%). Median Fuhrman grade was 2.5 overall, with penis metastases (n=4) having a median grade of 4. 95 of 111 (86%) cases reported patients with GU metastasis that had a prior nephrectomy for RCC. Patients with breast metastasis (n=16) had a significantly longer time between nephrectomy and metastatic diagnosis (90.1±63.1 months) than penile (12.7±16.1 months, n=6, p<0.01), bladder (28.7±26.6 months, n=15, p<0.01), or vaginal cohorts (6.7±5.2 months, n=3, p<0.05). Co-metastasis to extra-GU sites were most prevalent in penile metastasis (47.4%, n=9). The primary treatments for metastases were excisional surgery (79%), immunotherapy (18%), radiotherapy (14%), and tyrosine kinase inhibitors (13%). The breast cohort (n=10) reported a 90% survival rate at final follow-up, while the vaginal (n=8) and penile (n=12) cohorts reported survival rates of 50%. The urethra cohort (n=2) had a median survival time of 53 months, while the breast cohort (n=10) had a median survival time of 6 months. Conclusions: While kidney cancer's metastasis to other GU organs is relatively uncommon, it presents unique diagnostic and therapeutic challenges. Recognizing these patterns and understanding the biology behind such spread can offer insights into RCC's behavior and drive more effective treatments. [Table: see text]