**5. Mitigation strategies and surveillance guidelines**

A number of strategies including avoidance of RT and the use of lower doses of RT in modern COG and SIOP protocols may reduce the risk of SMNs. SIOP 93-01 allowed for omission of WLI in patients achieving radiographic CR of lung metastases following 6 weeks of chemotherapy or undergoing resection of all residual lung disease. Only 14%


#### **Table 2.**

*The Children's oncology group long-term follow-up guidelines (summary) recommendations for surveillance of childhood cancer survivors for secondary malignancy.*

of patients required lung RT as upfront therapy with this approach with good survival outcomes [27]. Similarly in COG AREN0533 trial, good survival rates were observed after omission of WLI in children whose tumors were without LOH at 1p and 16q and had complete response of lung nodules following chemotherapy at 6 weeks [28].

The International Guideline Harmonization Group updated their breast cancer surveillance recommendations in 2020. They noted that current data showed correlation between more moderate doses of RT (10–19Gy) and the risk of breast cancer. Additionally, there was a relationship between the use of anthracyclines and risk of breast cancer. Taking into account the risks of increased surveillance and relative benefit, the primary changes to previous recommendations were for surveillance for female patients with exposures of 10Gy or more to the chest, upper abdominal RT exposing the breast tissue at a young age and the use of anthracyclines [29].

The COG LTFU guidelines, version 5.0, provide extensive recommendations for the appropriate surveillance of childhood cancer survivors for common RT-induced toxicities observed in WT survivors (http://survivorshipguidelines.org). A summary of these guidelines is provided in **Table 2**.
