All in all, it still remains unanswered and a challenge to further investigate (i) why in the majority of cancer entities examined so far, overexpression of ALCAM is a negative prognostic marker, whereas in some other tumour types its downregulation is associated with an unfavourable prognosis and (ii) which role plays the differential cellular localisation of ALCAM in tumour progression and metastasation. This evidence concerns the gene ALCAM and cancer.