Cancers are each unique, so full diagnosis or complete elimination require precisely-directed heteropolyvalent agents - co-bodies.
Cancers are each unique, differing from each other and from normal tissues in the constellation of mutations present; yet existing agents are unable to select cancer cells for destruction or for diagnosis because they do not take advantage of that property of singularity. 'Co-bodies' are up to the task, being polyvalent and capable of assembly on the spot for each individual patient.