Introduction:

The Mayo Adhesive Probability (MAP) score is predictive of adherent perinephric fat in patients undergoing partial nephrectomy (PN) for renal cell carcinoma (RCC). Higher MAP scores have been extensively associated with worse perioperative outcomes. However, higher MAP has additionally demonstrated a greater risk of worse progression-free survival in surgically-treated localized RCC. Here, we examine the association between MAP score and aggressive pathological features on final analysis in patients undergoing PN or radical nephrectomy (RN) for clinical stage T1 (cT1) RCC. Furthermore, we examined the ability of MAP score to predict overall survival (OS) in our large, diverse institutional cohort.

Methods:

A retrospective review of our prospectively maintained nephrectomy database was conducted. Patients with cT1 renal masses and RCC histology were included. Exclusion criteria included nodal or metastatic disease, multiple renal masses, history of nephrectomy, estimated glomerular filtration rate (eGFR) <15 mL/min/1.73m2, unavailable imaging/laboratory data within 90 days preoperatively, and unknown or missing follow-up. 457 patients were analyzed, with the following staging:  281 cT1a (61.5%) and 176 cT1b (38.5%). 366 (80.1%) patients underwent PN while 91 (19.9%) received RN. Patients underwent MAP scoring and were dichotomized as low (1-3) or high (4-5). ANOVA for numerical variables and generalized chi-square tests for categorical variables were used to test for differences between low and high MAP scores. Multivariable Cox proportional hazards models and Kaplan-Meier curves were used to estimate the relationship between MAP score and 10-year OS.

Results:

136 (29.8%) patients had high MAP scores. High MAP associated with older age (63.6 vs 56.8 years; p<0.001), increased BMI (31.9 vs 30.4kg/m2; p=0.032), diabetes (37.5% vs 25.5%; p=0.010), hypertension (81.6% vs 60.1%; p<0.001), and poor preoperative renal function (median eGFR: 73.4 vs 83.4; p<0.001). High MAP was associated with increased operating time (276 vs 258 minutes; p=0.002), and 30-day complications (4.1% vs 0.6%; p=0.003). In addition, more aggressive features on final pathology were associated with high MAP, including tumor necrosis (22.8% vs 13.4%; p=0.013) and renal vein invasion (2.9% vs 0.3%; p=0.013), although no difference in perinephric fat invasion (10.3% vs 5.9%; p=0.099) or pathologic upstaging (14% vs 10.6%; p=0.302) was seen. High MAP was associated with worse OS for all RCC and clear-cell RCC only (ccRCC, Figure 1), which persisted on multivariable analysis (All RCC: HR 1.89; p=0.046; ccRCC: HR 3.88; p<0.001).

Conclusion:

High MAP scores were associated with more aggressive pathological features and predicted worse 10-year overall survival rates following nephrectomy in patients with cT1 RCC. High MAP score may indicate overall RCC aggressiveness, which can guide shared decision-making for surgeons and patients considering active surveillance, cryoablation, or nephrectomy for small renal masses. In addition, there may be a relationship between MAP and other comorbidities including hypertension, diabetes, and chronic kidney disease, which requires further exploration given the added surgical risk.

Funding: John Robinson Family Foundation, Christopher Churchill Foundation, and Cox Immunology Fund