FISH 13, resulting in a haploinsufficiency of RB1 and other genes mapping to chromosome 13, as well as activation of IGF1R, appears to have an amplifying effect on cell cycle gene expression, thus providing a molecular explanation for the dire outcome of patients with CA 13 compared with those with other CAs.
Long-term follow-up on Total Therapy I revealed, with a median follow-up of about 10 years, median durations of event-free survival (EFS) and overall survival (OS) of 37 and 80 mos in the 88% of patients lacking cytogenetic abnormalities (CA) of chromosome 13 compared to only 28 and 34 mos in those with CA 13.