In one embodiment, the invention provides a method of treating a subject suffering from a breast cancer tumor which is non-responsive or intrinsically resistant to anti-estrogen therapy comprising administering a therapeutically effective amount of an inhibitor of alternative (ALT) non-homologous end joining (NHEJ) factor to the subject.In another embodiment the invention provides a method of treating a subject who suffers from a pancreatic cancer which is non-responsive to chemotherapy and/or radiation comprising co-administering a therapeutically effective amount of PARP1 inhibitor and a DNA ligase IIIα inhibitor to the subject. Related diagnostic methods, nucleic acid arrays, devices and kits are also provided.
