Radiation exposure assessment and risk of subsequent tumors in childhood cancer survivors

Patients who survive childhood cancer are at a substantial risk for long-term adverse health outcomes later in life. This thesis describes the Dutch LATER cohort, which includes childhood cancer patients who were diagnosed and/or treated in one of seven academic centers between 1963-2002, before the age of 18 years, and who survived at least 5 years post diagnosis. In chapter 2 we evaluated temporal trends in radiotherapy; also we provide a literature review on radiotherapy exposure quantification methods used in pediatric cancer survivorship studies (Chapter 3). Chapter 4 focusses on various measures to express radiation exposure for cohort members who had radiotherapy. In the second part of the thesis the radiotherapy parameters developed in Chapter 4 are applied to investigate risk factors for subsequent solid benign tumors and skin cancers. Chapter 5 describes the overall risk of subsequent solid benign tumors in childhood cancer survivors, and a sibling comparison group, with specific assessments on uterine leiomyoma, breast fibroadenoma, nerve sheath tumors, and osteochondromas. In Chapter 6 the risk of subsequent benign meningioma after childhood cancer is studied, especially the contributions of radiation dose, exposed cranial volume, and age at treatment. Chapter 7 describes the risk of colorectal adenomas and cancer, with emphasis on the effects of specific childhood cancer treatments. Finally, in Chapter 8 the radiotherapy parameters regarding skin exposure during former radiotherapy are used to evaluate the risk of skin cancers, with focus on the effect of radiotherapy volume and dose on the skin, and other treatment factors.