The present invention relates to compositions and methods for treating invasive or metastatic cancer, particularly metastatic colon cancer using the B-submit of shiga toxin. The coarse delay segment includes a coarse delay range. The engagement arms are shaped so as define three peak complexes at the three respective junctures, and three trough complexes, each of which is between two of the peak complexes. Embodiments are disclosed using a mirrorbeam splitter arrangement to switch between modes and an embodiment including dichroic filters serving as fractional beam splitters.