Although the skeleton is not a preferred site of overt metastasis in colorectal cancer, demonstration of tumour cells in bone marrow has to be seen as evidence of the general disseminative capability of an individual tumour.¹ Other observations such as involuntary transmission of tumour by organ grafts directly supports the notion that very few quiescent cells lodging at improbable sites, such as the kidney or heart, suffice to generate de novo metastatic disease in the organ recipient.² The TNM classification recommends mention of the presence of disseminated tumour cells as a facultative factor for metastatisation (M0 (i+) or M0 (mol+)) according to the immunological or molecular detection technique.³

However, the results …