Patients will be given general anesthesia. A laparoscopic trocar and additional ports will be placed under direct visualization and pneumoperitoneum will be established. Once the operating surgeon determines that the lesions as evaluated on intraoperative ultrasound remain amenable to MWA, ablations will be performed with a 2.45-gigahertz (GHz) generator with a 1.8-mm-diameter transcutaneous antenna (Acculis pMTA Accu2i; AngioDynamics Inc., Denmead, Hampshire, UK). Additional ablations will be performed sequentially. Laparoscopic core needle biopsy of lesions will be performed and submitted for permanent pathologic sectioning per current treatment standards. At the conclusion of the ablation, a collapsed titanium clip will be inserted into the microwave antenna tract as a radiographic fiducial marker. Hemostasis of the ablation track will be ensured using a combination of microwave energy, monopolar electrocautery, and/or topical hemostatics.

General anesthesia will be induced. A laparoscopic trocar and additional ports will be placed under direct visualization and pneumoperitoneum will be established. The liver will be evaluated with intraoperative ultrasound (BK Medical A/S, Herlev, Denmark). Laparoscopic core needle biopsy of lesions will be performed. Partial hepatectomy may be carried out with parenchymal precoagulation with radiofrequency electrosurgical devices such as the LigaSure™ (Covidien, Medtronic; Minneapolis, MN), Harmonic® (Ethicon Endosurgery; Cincinnati, OH), or saline-coupled radiofrequency ablation device (Aquamantys™; Covidien/Medtronic; Minneapolis, MN); hepatic parenchymal transection can be performed as above or with the use of stapling devices to ligate and divide parenchyma. Hepatic vascular inflow occlusion will be performed at the surgeon's discretion. A topical hemostatic may be used along the transected hepatic parenchyma. Resected specimens will be preserved in formalin for pathology.

Laparoscopic or robot-assisted laparoscopic microwave ablation of cancerous lesions with a 2.45-GHz microwave generator and a 1.8-mm-diameter transcutaneous antenna.

Local disease control is measured from time of randomization and is defined as the absence of local recurrence of metastatic adenocarcinoma of the colon or rectum as determined by diagnostic imaging.