What does it mean if the drug "rarely causes a serious condition called neuroleptic malignant syndrome" what is that a type of cancer or something?

NMS. Neuroleptic malignant syndrome (nms) is the combination of hyperthermia, rigidity, and autonomic dysregulation that can be a serious complication with antipsychotic medications. Newer atypical antipsychotics can cause this as well as older ones. Dopamine d2 receptor blockade in extrapyramidal pathways, spinal cord, and hypothalamus leads to these symptoms. There can be direct muscle effects too.