Some studies have reported that minimally invasive follicular carcinoma (MIFC) with vascular invasion is associated with compromised prognosis, leading to an ongoing debate regarding extent of surgery for MIFC. Our goal was to identify predictors of vascular invasion and determine its impact on patterns of care. Adult patients with MIFC were culled from the National Cancer Database, 2010-2011, and segregated according to the presence/absence of capsular or vascular invasion. Variables of interest were examined using Chi-square and student's t tests. Multivariate analysis was performed with logistic regression. A total of 617 patients with MIFC were identified: 54% with capsular invasion only and 46% with vascular invasion. Demographic characteristics were similarly distributed between the two groups. Tumor size was larger in patients with vascular invasion (mean = 35.7 vs. 29.2 mm capsular invasion only, p < 0.001); a 2% increase in risk of vascular invasion was observed with each 1 mm increase in size. The rate of total thyroidectomy was similar for MIFCs with vascular invasion compared to capsular invasion only (72.9 vs. 75.1%, p = 0.537). The RAI administration rate was higher in patients with vascular invasion (62.1 vs. 52.6% capsular invasion only, p = 0.017). In multivariate analysis, the presence of vascular invasion was independently associated with increased likelihood of receiving RAI (OR 1.641, p = 0.007). MIFC remains aggressively treated despite current guidelines favoring a more conservative approach. Building consensus around MIFC management is important for standardization of practice patterns and improvement in quality of care.
Keywords: Minimally invasive follicular carcinoma; RAI; Surgery; Thyroid.