Su HI, Kwan B, Whitcomb BW, et al. - In view of the shortened reproductive lifespans in many female survivors of adolescent and young adult cancers (AYA survivors), researchers here sought to ascertain the timing and duration of ovarian function after cancer treatment. They modeled the trajectory of ovarian function over two decades following cancer treatment and examined the variation in trajectories by treatment gonadotoxicity and age. In a prospective cohort, 1,905 dried blood spots were obtained every 6 months for up to 18 months from 763 AYA survivors ages 18-39 at variable times since cancer treatment completion. Timing and duration of ovarian function strongly depended on treatment gonadotoxicity and age at treatment in this large AYA survivor cohort. Following low or moderately gonadotoxic treatments, there was an increase in AMH levels over 2-3 years and then the levels plateaued over 10-15 years before declining. In contrast, following highly gonadotoxic treatment, overall lower AMH levels were observed and these levels declined shortly after peak at 2-3 years. Higher trajectories were observed in correlation with younger age at treatment, however survivors exposed to highly gonadotoxic treatments did not exhibit a protective effect of younger age. These novel findings with more precise information may aid in reproductive decision-making.