CDKN2A and childhood malignant neoplasm: While our study is limited by the use of a single biomarker of cellular senescence, our findings of detectable p16INK4a mRNA expression levels higher in young adult childhood cancer survivors than in persons of similar age in the general population (39), combined with the presence of low grade inflammation in our population, signifies that cellular senescence is a potential pathobiological mechanism for premature physiologic ageing in survivors of childhood cancer, contributing to exercise capacities comparable to adults decades older.