Techniques for treating a tumor and vaccinating against cancer are described. The techniques include treating the tumor by positioning electrodes over an interface between the tumor and non-tumor tissue and applying sub-microsecond pulsed electric fields. The positioning is facilitated by an imaginary contour line of a threshold value of the electric field. In an example, the imaginary contour line is overlaid over images that include the tumor such that the electrodes are properly positioned over the tumor. The techniques also include vaccinating against cancer by passing sub-microsecond pulsed electric fields through tumor cells of a subject sufficient to cause the tumor cells to express calreticulin on surface membranes. The tumor cells are extracted and introduced with the expressed calreticulin into the subject or another subject, thereby providing a vaccination.