Purpose

To investigate relapse detection methods among children and adolescents with nongerminomatous malignant germ cell tumors (MGCTs) and to determine whether tumor markers alone might be sufficient for surveillance.

Methods

We retrospectively reviewed all patients enrolled in a phase III, single-arm trial for low-risk and intermediate-risk MGCTs. The method used to detect relapse was assessed based on case report forms, tumor markers, imaging, and pathology reports. Relapses were classified into one of two categories on the basis of whether they were (1) detectable by tumor marker elevation or (2) not detectable by tumor markers.

Results

A total of 302 patients were enrolled, and 284 patients had complete data for review. Seven patients had normal tumor markers at initial diagnosis, and none experienced a relapse. At a median follow-up of 5.3 years, 48 patients (16.9%) had experienced a relapse. After central review, 47 of 48 relapses (98%) were detected by tumor marker elevation. Of the 47 patients, 16 (33.3%) had abnormal tumor markers with normal/unknown imaging, 31 patients (64.6%) had abnormal tumor markers with abnormal imaging, and one patient (2.1%) had abnormal imaging with unknown marker levels at relapse.

Conclusion

Tumor marker elevation is a highly sensitive method of relapse surveillance, at least among children and adolescents with tumor marker elevation at initial diagnosis. Eliminating exposure to imaging with ionizing radiation may enhance the safety of relapse surveillance in patients treated for MGCT.

Over the past decade, wingless-activated (WNT) medulloblastoma has been identified as a candidate for therapy de-escalation based on excellent survival; however, a paucity of relapses has precluded additional analyses of markers of relapse. To address this gap in knowledge, an international cohort of 93 molecularly confirmed WNT MB was assembled, where 5-year progression-free survival is 0.84 (95%, 0.763-0.925) with 15 relapsed individuals identified. Maintenance chemotherapy is identified as a strong predictor of relapse, with individuals receiving high doses of cyclophosphamide or ifosphamide having only one very late molecularly confirmed relapse (p = 0.032). The anatomical location of recurrence is metastatic in 12 of 15 relapses, with 8 of 12 metastatic relapses in the lateral ventricles. Maintenance chemotherapy, specifically cumulative cyclophosphamide doses, is a significant predictor of relapse across WNT MB. Future efforts to de-escalate therapy need to carefully consider not only the radiation dose but also the chemotherapy regimen and the propensity for metastatic relapses.