On MRI or mammograms, the resorption can be seen as calcification. A trained radiologist can distinguish between microcalcification arising from fat transfer vs. breast cancer. However, there is limited scientific evidence regarding the effect of stem cells, contained within the transferred fat, on breast cancer. Studies in the laboratory have shown that presence of stem cells favour the growth of tumour cells, but this has not yet been substantiated by clinical trials. The American Society of Plastic Surgeons (ASPS) has advised mammograms before and after fat transfer to provide re-assurance to the patient regarding any new abnormalities that may develop. It advises against fat transfer in cosmetic patients at high-risk of breast cancer such as those with personal or familial history of breast cancer and/or BRCA-1, BRCA-2 gene inheritance.
In the UK, guidelines from the Breast Interface group (BAPRAS and BASO) were published in 2012 are available on the link: http://www.bapras.org.uk/downloaddoc.asp?id=666.