Large Population Analysis of Secondary Cancers in Pediatric Leukemia Survivors

Introduction: Survivors of childhood cancer have an increased risk of developing a subsequent secondary malignant neoplasm (SMN). Among five-year survivors of primary cancer, SMNs account for nearly half of non-relapse deaths, which make them the most frequent cause of non-relapse mortality. Leukemia is the most common childhood cancer and the five-year survival rate of leukemia has drastically improved over the past two decades. Therefore, the chances of developing SMNs are higher in pediatric (0-19 years) leukemia survivors.

Methods: The US based Surveillance, Epidemiology, and End Results (SEER-18) database (1973-2014) was probed for SMNs in the pediatric population (age ≤ 19). Variables Sequence-number central, primary site and ICCC3WHO were used to identify the first and second cancers among patients who developed SMN.

Results: Our SEER database analysis found 99,380 cases of pediatric primary malignancies (0-19 years), of which 1803 (1.81%) patients developed SMN. The breakdown of SMNs in pediatric leukemia survivors (n = 251) showed thyroid carcinoma (18.33% of cases) as the most common second cancer, followed by sarcoma (15.14%), astrocytoma (10.36%), lymphoma (9.56%), salivary gland carcinoma (7.17%), melanoma (4.38%), and breast cancer (3.98%). Interestingly, we found that over 76% of SMNs that were developed by leukemia patients occurred within 20 years after initial leukemia diagnosis. However, some SMNs occur during later age, for example, the mean age for breast cancer occurrence in leukemia survivors is 26.20 ± 8.53 years after initial leukemia diagnosis.

Conclusions: Our study presented comprehensive rates of SMNs among pediatric cancers survivors, and the potential SMNs for pediatric leukemia survivors. This information could we used by oncologists, patients, patient families, and cancer researchers to understand the long-term risks that are associated with the development of SMNs in pediatric leukemia survivors.