Despite the presence of microvascular channels in melanomas. The process of diffusion allows only the penetration of small molecules into the tumour, the size of the whole antibody molecule is obviously far too big to target cells behind the endothelial barrier as the target molecule CEACAM is clearly expressed in the tumour as shown in tissue sections. Therefore, the access of i.v. administrated anti CEACAM antibodies is limited to tumour cells surrounding blood vessels despite the fact, that many more tumour cells express CEACAM if studied in tissue sections. This lack of penetration might also explain why studies on the usage of anti CEA antibodies have not found acceptance in routine clinical practice. In order to target a wider range of CEACAM positive tumour cells, smaller target-specific molecules like DARPINs or nanobodies against CEACAM will be tested to see if they could reach the in vivo CEACAM binding sites to a greater LY2109761 extent. However, we could show that the target CEACAM could be studied with our melanoma FEMX-1 model and used for molecular imaging. In industrialized settings less advanced disease, younger age, injection drug use and homelessness have been associated with loss to follow-up. Loss to follow-up is more common in resource-poor settings. In an Antiretroviral Treatment in Lower Income Countries study, loss to follow-up after 1 year was above 40% in some programs, and associated with more advanced clinical disease and lower CD4 cell counts. Similarly, an analysis of the large ART programme jointly administered by the Zambian Ministry of Health and the Centre for Infectious Disease Research in Zambia showed that predictors of treatment failure or death also predicted loss to follow-up. A meta-analysis of studies that traced patients lost to follow-up to ascertain their vital status showed that in sub-Saharan Africa 40% of those traced had died. High rates of loss to follow-up may affect mortality estimates in ART programmes if patients lost to follow-up have a different prognosis compared to similar patients remaining in care. Obtaining valid estimates of loss to follow-up at different points in time is therefore important when evaluating ART programmes. Death is a competing risk of loss to follow-up: patients who die can no longer become lost to follow-up. Competing risks are defined as events that prevent the outcome of interest from occurring. They are common in longitudinal studies and are particularly important in populations at high risk of death. For example, death from all causes is a competing risk when studying recurrences after treatment of cancer, and death from other causes is a competing risk when studying a specific cause of death. In standard Kaplan-Meier analyses, the follow-up of those developing a competing event is simply censored, assuming that the probability of the outcome of interest is the same as that of comparable patients remaining under observation. However, this assumption is invalid because the outcome of interest can no longer occur in those developing the competing event.