OBJECTIVES: Recent consensus guidelines herald an expanding role for minimally-invasive surgery (MIS) in the treatment of adrenocortical carcinoma (ACC). However, MIS has been associated with non-curative resection and locoregional recurrence. We aimed to identify risk factors for margin-positivity among patients who undergo MIS resection for ACC. We hypothesized that a simple nomogram can accurately identify patients most suitable for oncologically-sound MIS resection.

METHODS: Curative-intent resections for ACC were identified through the National Cancer Database spanning 2010-2018. Trends in MIS utilization were reported using Pearson correlation coefficient. Factors associated with margin-positive resection were identified among preoperatively-available variables using multivariable logistic regression, then incorporated into a predictive model. Model quality was cross-validated using an 80% training dataset and 20% test dataset.

RESULTS: Among 1260 ACC cases, 38.6% (486) underwent MIS resection. MIS utilization increased over time at non-academic centers (R=0.79, p=0.011), but not at academic centers (R=0.08, p=0.834). Factors associated with margin-positive MIS resection were increasing age, non-academic center (OR 2.0, p=0.008), cT3 (OR 5.2, p<0.001) and cT4 tumors (OR 28.0, p<0.001), and right-sided tumors (OR 2.1, p=0.005). A predictive model incorporating these four factors produced favorable c-statistics of 0.75 in the training dataset and 0.72 in the test dataset. The corresponding predictive nomogram is presented in Figure 1.

CONCLUSIONS: An increasing proportion of adrenocortical carcinomas are resected via minimally-invasive operations, particularly at non-academic centers. Patient selection based on a few key factors can minimize the risk of non-curative surgery.

Figure 1: Nomogram estimating the risk of margin-positivity for laparoscopic- and robotic-resected adrenocortical carcinoma. For example, a 65-year-old patient (33 pts) with a cT3 (57 pts), right-sided tumor (25 pts) at an academic center (0 pts) would have a 50% risk of margin-positive resection.