Puberty & hormone problems after treatment — understanding what your child may face

Yes. Certain chemotherapy agents — particularly those belonging to the alkylating class — can affect the gonads (ovaries in girls, testes in boys), reducing the hormones that normally trigger puberty. Radiation to the brain, spine, or pelvis can also interfere with the signals the pituitary gland sends to start puberty. Not every child treated for cancer will experience delayed puberty, but the risk depends on the type of treatment, the doses used, and the age of the child at the time of treatment. A paediatric oncologist working with a paediatric endocrinologist can evaluate whether puberty is progressing on schedule and what, if anything, needs to be done.

In girls, signs include no breast development by age 13, or no first period by age 15–16. In boys, signs include no testicular enlargement by age 14, or no other signs of puberty such as voice changes or pubic hair. Both boys and girls may show slower height gain or no growth spurt during the usual teenage years. These are not definitive diagnoses — only a specialist evaluation with hormone blood tests and a bone-age X-ray can confirm whether puberty is truly delayed and what is causing it.

Growth hormone (GH) is produced by the pituitary gland at the base of the brain. Radiation therapy to the brain — used to treat brain tumours, some leukaemias, and head-and-neck cancers — can damage the pituitary gland or the hypothalamus that controls it. When GH production falls, children grow more slowly than expected and may not reach their full adult height. GH deficiency is one of the most common hormone late effects after cranial radiation. It is usually confirmed with a stimulation test, and many children benefit from GH replacement therapy, which is given as a daily injection. Decisions about starting replacement must involve both an endocrinologist and the oncology team.

Fertility after cancer treatment is a genuine concern, and the answer depends heavily on the type of treatment she received. High doses of certain chemotherapy agents and radiation to the pelvis or whole abdomen carry the highest risk of affecting ovarian function. Some girls treated in childhood go through premature ovarian insufficiency — where the ovaries stop working before the natural age of menopause. However, many girls who received lower-dose treatments retain normal ovarian function and go on to have pregnancies without difficulty. A long-term follow-up clinic can monitor ovarian hormone levels (FSH, LH, oestrogen) over the years and refer to a reproductive endocrinologist when your daughter is ready to discuss her fertility options.

The frequency of hormone monitoring depends on the type of treatment your child received. Children who had brain radiation or high-dose chemotherapy with alkylating agents generally need annual hormone checks — including growth hormone, thyroid function, and gonadal hormones — starting from the first year off treatment. Children who received treatments with a lower risk to the endocrine system may need checks every two to three years. Your child's survivorship care plan, drawn up by the oncology team, should specify what tests are needed and when. Never skip these appointments even when your child appears to be growing normally, because some deficiencies are silent until they cause problems.

CION's coordinated survivorship approach means your child's paediatric oncologist works closely with endocrinology and other specialists as part of a structured long-term follow-up plan. We do not treat survivorship as an afterthought — a dedicated survivorship care plan is part of every child's treatment journey at CION. If hormone problems or puberty concerns are identified, we coordinate referrals, interpret results in the context of your child's cancer history, and communicate clearly so you always understand what is happening and why. You can reach our team for a 45-minute consultation, free for all cancer patients.