• Radiation to the testes in the amount of 1–3 Gy will cause sperm production to stop. This may be reversible and sperm production might resume after treatment. • Radiation to the testes in the amount of 3–6 Gy will cause sperm production to stop which is likely NOT reversible. • Radiation to the testes in the amount of > 6 Gy will cause an irreversible stop in sperm production. Boys who receive much higher doses of radiation to the testes may also develop ley- dig cell problems. Leydig cells are responsible for making the hormone testosterone. Radiation to the testes in the amount of 20 Gy or higher may cause Leydig cells to stop functioning. This can cause infertility and low testosterone levels. CHEMOTHERAPY EFFECTS The type and dose of chemotherapy determine which fertility problems occur in children treated for cancer. The medicines most likely to cause fertility problems are called alkylating agents. Your pediatric oncologist will discuss the types of chemother- apy your child may receive. Chemotherapy drugs most likely to result in fertility problems in any child with cancer include:
Alkylating Agents Cyclophosphamide Ifosfamide Nitrogen Mustard Procarbazine BCNU (Carmustine) CCNU (Lomustine) Melphalan
Heavy Metals Carboplatin* Cisplatin*
Nonclassical Alkylating Agents
DTIC (Dacarbazine)* Temozolomide (Temodar)*
Thiotepa Busulfan
*Less likely to result in infertility in both females and males if given without alkylating agents or heavy metals. Males treated for cancer are more sensitive to the effects of alkylating chemotherapy drugs. Higher total doses of alkylating and heavy metal chemotherapy can result in higher levels of testicular dysfunction. Testicular dysfunction is defined by sperm production and includes • lack of sperm (azoospermia) • low sperm oligospermia) • small testes • delayed pubertal development.
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