Which specific childhood/young adult cancers show stage 4 increases or drops?

The retrieved studies do not contain population-level stage 4 trend data for any childhood or young adult cancer type. They are about treatment response, molecular markers, and case reports.

The evidence you provided does not answer the question. It contains no population registry, no time series, and no comparison of stage 4 proportions across calendar years. There are studies on neuroblastoma gene expression [1], leukemia survival in Tanzania [2], and osteosarcoma platelet indices [3], but none track whether the fraction of cases diagnosed at stage 4 is rising or falling. That is a separate epidemiological question that requires cancer registry data (SEER, GLOBOCAN) over decades.

The question is fair, but this retrieval is the wrong tool. Population-level stage migration (the shift of cases into stage 4 as imaging improves) is a documented phenomenon in several solid tumors, including bone sarcomas and lymphomas. It does not mean the disease is genuinely increasing; it means scans are catching more metastases. That distinction matters for the parent who hears "stage 4 is rising." The rise is often in detection, not in disease.

My call: this retrieval cannot tell you which cancer types show increasing or decreasing stage 4 rates, because it contains no incidence or stage-migration data. The question would need a SEER-based analysis of stage distribution over time, broken down by histology. That analysis does exist in the literature for many pediatric cancers, but it is not in these records. Confidence: not clear.