Association of transanal minimally invasive surgical approach with oncologic outcomes over conventional transanal excision for early-stage rectal cancer: An analysis of the US Rectal Cancer Consortium.

145 Background: For early-stage rectal cancer, minimally invasive surgical (MIS) approaches such as transanal endoscopic microsurgery (TEM) and transanal minimally invasive surgery (TAMIS) have not been widely adopted over conventional transanal excision (TAE). Direct comparisons are lacking. Our aim was to compare oncologic and perioperative outcomes between the two approaches. Methods: We identified patients with Tis or T1 tumors who underwent TAE or MIS (TEM or TAMIS) between 2007-2017 from the US Rectal Cancer Consortium database. Patients who received neoadjuvant therapy were excluded. Primary outcomes were rate of recurrence and recurrence-free survival (RFS). Results: Of 1881 patients, 89 met inclusion criteria: 44 TAE and 45 MIS (20 TEM, 25 TAMIS). Median age was similar between groups (63.5 years TAE vs 61 years MIS; p=0.582). Patients in each group had similar functional status and tumor size (1.86 cm TAE vs 1.79 cm MIS, p=0.837). The majority of patients had tumors ≤ 6 cm from the anal verge (75.7% TAE vs 65.5% MIS, p=0.544). The TAE group had a 10.3% margin positive rate versus 0% in the MIS group (p=0.049). There was a lower incidence of recurrence in the MIS group (4.5%) compared to TAE (26%, p=0.01); all recurred locally except for one in the TAE group. Median follow-up time was 23.7 months. On Kaplan-Meier analysis, MIS approach was associated with improved 5-year RFS (86.4%, p=0.005) and local RFS (86.4%, p=0.01), versus TAE (46.9% and 50.5%, respectively). On univariate cox regression analysis, lymphovascular invasion was associated with worse RFS (HR 4.23, p=0.033) and local RFS (HR 5.26, p=0.02), while MIS approach was associated with improved RFS (HR 0.15, p=0.015) and local RFS (HR 0.17, p=0.023). On multivariable cox regression, only MIS approach remained associated with improved RFS (HR 0.09, p=0.028) and local RFS (HR 0.11, p=0.045). Perioperative complication and readmission rates were equal between the two groups. Conclusions: In patients with Tis and T1 rectal cancers who undergo local excision, an MIS approach (TEM or TAMIS) is associated with a decreased rate of recurrence and improved RFS and local RFS compared to TAE, with no significant difference in perioperative complication rate. The MIS approach should be more frequently incorporated into standard practice. [Table: see text]