Unmet needs in the management of patients with bilateral synchronous renal masses: the rationale for clinical decision-making.

Background: Bilateral synchronous renal masses (BSRMs) are a rare finding, and the optimal treatment strategy remains undetermined. This study depicts the management of BSRM at eight European high-volume centers.

Methods: This is a retrospective analysis of prospective institutional databases collecting all patients presenting with clinical T1-2 N0 M0 BSRMs between 1993 and 2020 at 8 tertiary referral high-volume centers for renal cancer treatment in Europe. The treatment options included active surveillance (AS), tumor ablation (TA) and surgery (partial and radical nephrectomy).

Results: Overall, 134 patients were analyzed. Renal mass biopsy prior treatment was performed in 8% of cases. 15%, 4%, and 81% of patients underwent AS, a combination of surgery and TA, and bilateral (one-stage or two-stage) surgery. Among patients undergoing bilateral surgery (N.=109), a staged approach was chosen in 78% (N.=85) of cases treating the lower complexity tumor first in 51/85 (60%) cases and in 34/85 (40%) treating the higher complexity tumor first. Concordance of the histological analysis was found in 77% of patients with 10% of bilateral benign masses.

Conclusions: Even if considering only referral centers, a high heterogeneity for decision-making in the treatment of BSRM should be expected. Advances in genetic diagnosis, the implementation of novel imaging technologies, and the strengthening role of alternative treatment, may lead to a standardized decision-making process in the setting of BSRMs.