Blood Markers Alone Okay For Surveillance With Some Pediatric Cancers

Tumor markers alone may be adequate to monitor for relapse among children and teens with malignant germ cell tumors (MGCTs), according to a study published online Dec. 21, 2018 in the Journal of Clinical Oncology. The authors say that eliminating routine CT scans from surveillance protocols for children who have elevated tumor markers at diagnosis could substantially reduce unnecessary radiation exposure and may enhance the safety of relapse surveillance.

Current pediatric North American MGCT protocols include CT scans of the chest, abdomen, and pelvis for surveillance following treatment, with repeat scans called for quarterly for the first year, twice annually during the second year, and annually for up to 5 years post-treatment. However, there are concerns about significant cumulative radiation dose, particularly for cancer with such good prognoses.

The researchers retrospectively reviewed data for 284 patients enrolled in a phase III, single-arm trial for low-risk and intermediate-risk MGCTs in order to identify the method used to detect relapse (e.g., tumor markers, imaging, and/or pathology reports). Serial alpha-fetoprotein (AFP) and beta–human chorionic gonadotropin (b-HCG) measurements were used for tumor marker monitoring.

Over a median 5.3 years of follow-up, the researchers found that none of the seven patients who had normal tumor markers at initial diagnosis experienced a relapse. However, 48 patients with elevated tumor markers at diagnosis did experience a relapse. Nearly all (47 of 48) relapses were detected by tumor marker elevation, including 39 with elevated AFP elevation, one with elevated b-HCG, and seven with elevated levels of both tumor markers. One-third of patients (n = 16) had no reported site of relapse (normal imaging), with elevated tumor markers being the indicator of relapse, while two-thirds of patients had both abnormal tumor markers and imaging.

“If the 284 patients enrolled in this trial each had the nine CT scans prescribed by protocol for surveillance, they would have collectively undergone 2,556 CT scans of the chest, abdomen, and pelvis,” write the authors led by Adriana Fonseca, M.D., from University of Toronto in Canada. “Using the estimates proposed by Miglioretti et al., that a radiation-induced solid cancer is projected to result from every 300 to 390 abdomen/pelvis CT scans and every 330 to 480 chest CT scans in girls, we appreciate the significant risks associated with this surveillance schedule, especially when nearly all patients could have had their relapse detected by tumor markers alone.”

Takeaway: Tumor markers may be reasonable for primary surveillance following treatment for MGCTs for patients with positive tumor markers at diagnosis, thereby substantially cutting the number of CT scans needed for routine monitoring.