The present invention provides a treatment method to excise a cancerous lesion, such as in the breast, with subsequent ablation of the margin. The method provides for location and excision with ablation under open guidance or guided imaging and for diagnosis by cytology. The method may be a minimally, invasive same day method with diagnosis before or immediately after excision. Also provided is a method of treating close or positive margins of an excisional site of a cancerous lesion in a breast by ablating the margin while monitoring the fluorescence of a fluorophor at the site to determine when ablation of the close or positive margin has occurred.