Co-occurrence in body site of malformations and cancer

In many malformation syndromes benign and malignant tumours develop more frequently than in the general population. Malformations result from an abnormal intrinsic developmental process. It can be hypothesised that disturbed regulation of cell growth as can become evident by the presence of benign and malignant tumours, which will occur at the same site of a malformation or at other sites at which the gene involved in the malformation is functioning. The present study aimed to compare the localisation of malignant and benign tumours to the localisation of major and minor characteristics of syndromes that have either of two malformations, i.e. microtia and hypospadias. To eliminate co-occurrence of a malformation syndrome and tumours by chance we confined evaluations to syndromes which have been described in >100 individuals. We identified 11 syndromes associated with microtia and 26 syndromes associated with hypospadias, for which co-localisation of (benign and malignant) tumours with (major and minor) syndrome characteristics was determined. In both groups of syndromes tumours were found to be localised at the same body site as the major and minor characteristics of the syndromes in two-third of the tumours. There was no significant difference in co-occurrence in site between benign and malignant tumours. We conclude that in two groups of malformation syndromes which go along with a different core malformation, benign and malignant tumours co-localise with the core malformation or with other sites at which the gene involved is functioning. This adds further proof that tumours in malformation syndromes can usually be explained by abnormal functioning of the same gene that has caused the malformation syndrome.