Time to Next Treatment

Time to next treatment may be useful because it is easier and cheaper to measure routinely than progression-free survival. Time to next treatment is defined as time from enrolment to the next treatment or death from any cause. Surrogacy assessment requires evidence that treatment effects and individual prognosis align between time to next treatment and progression-free survival. Line of treatment will be identified from systemic anticancer therapy records using rules based on intervals between regimen changes and line-of-treatment index agents. Time to next treatment will be derived from systemic anticancer therapy data and evaluated as a surrogate endpoint for progression-free survival.