Ablation devices and associated methods are provided for use in ablating the margin of a cavity such as a surgical or body cavity. The ablation apparatus includes an integral or connected elongate probe and an elongate sleeve. Suction can be applied with a vacuum source operably connected to the proximal end region of the sleeve, whereby tissue of the surgical cavity is drawn against the surface of the sleeve. The probe includes one or more electrodes disposed at the probe's distal end region, for ablating tissue when the electrode(s) are activated to create an ablated margin of tissue at least partially surrounding the surgical cavity.