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Subsequent primary neoplasms in survivors of childhood cancer in Slovenia -- trends and risk factors
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  • Maja Česen Mazič,
  • Raoul Reulen,
  • Janez Jazbec,
  • Lorna Zaletel Zadravec
Maja Česen Mazič
Department for Pediatric Hematology and Oncology, University Children Hospital Ljubljana, Ljubljana, Slovenia

Corresponding Author:[email protected]

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Raoul Reulen
University of Birmingham
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Janez Jazbec
University Medical Center Ljubljana
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Lorna Zaletel Zadravec
Institute of Oncology Ljubljana Division of Radiotherapy
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ABSTRACT Aim To investigate long-term risk and spectrum of subsequent primary neoplasm (SPN) in childhood cancer patients in Slovenia; and to identify how trends in therapy influenced cumulative incidence of SPN. Methods The population-based cohort comprises 3271 childhood cancer patients diagnosed in Slovenia aged ≤ 18 years between 1961 and 2013 with a follow-up through 2018. Main outcome measures are standardised incidence ratios (SIRs), absolute excess risks (AERs), and cumulative incidence of SPN. Results After median follow-up time of 21.5 years for 5-year survivors, 230 patients experienced 273 SPN, including 183 subsequent malignant neoplasm (SMN), 34 meningiomas and 56 nonmelanoma skin cancers. 10.5% patients received radiotherapy only, 31% chemotherapy only, 26.9% a combination of chemotherapy and radiotherapy and 16.1% surgery only. The overall SIR was almost 3 times more than expected (SIR 2.9, 95% CI 2.5 to 3.3), with survivors still at 1.7-fold increased risk after 40 years from diagnosis. The observed cumulative incidence of developing an SMN at 40 years after childhood cancer diagnosis was significantly lower for patients having surgery only (Pheterogeneity<0.001). Despite reduced use of radiotherapy after 1995 there is no significant difference in cumulative incidence of developing an SMN for the first 15 years after diagnosis (p=0.36). Conclusion Risks of developing a SMN in this study are similar to other population-based cohorts. What is new, are treatment data for our cohort, showing that most intensive treatment with radiotherapy and chemotherapy was implemented later in practice and radiotherapy also declined slower compared to high income countries.