Late Effects of Cancer Therapy
On this page
Direct answer
Late effects of cancer therapy are treatment-related harms that appear months to years after chemotherapy, radiotherapy or surgery has ended. The major ones are secondary malignancy, anthracycline cardiomyopathy, gonadal failure and endocrine deficits. Many depend on the cumulative drug dose and the irradiated field, so survivorship care uses the treatment history to decide what to monitor.
What you must remember
- Secondary malignancy: alkylating agents, topoisomerase II inhibitors and radiotherapy raise the risk of later cancers, with therapy-related AML and MDS as classic examples.
- Anthracycline cardiotoxicity: cardiomyopathy rises steeply with cumulative doxorubicin above roughly 450 to 550 mg/m2, and mediastinal radiotherapy adds to the risk.
- Gonadal toxicity: alkylating agents, especially cyclophosphamide, cause infertility, and gonadotropin-releasing hormone agonists may protect ovarian function during treatment.
- Thyroid and pituitary: neck radiotherapy causes hypothyroidism, while cranial irradiation in childhood causes growth hormone deficiency and hypothalamic-pituitary failure.
- Pulmonary toxicity: bleomycin causes pneumonitis and fibrosis, and chest radiotherapy and high inspired oxygen increase the injury.
- Neurocognitive effects: cranial irradiation and high-dose methotrexate can impair cognition, most notably in children.
- Survivorship plan: a treatment summary, with agents, cumulative doses and fields, is the basis for risk-based screening.
Building a risk-based survivorship plan from the treatment history
Late effects are predicted from what the patient received, so the plan begins with a complete record of treatment. The steps below move from the record to screening and counselling, and each one depends on the step before.
- Record the exposures. Note the agents, cumulative doses, radiation fields and dates, because they determine the risk.
- Map the risk. Anthracycline dose and chest radiotherapy point to the heart, alkylating agents to the gonads and marrow, and neck or cranial fields to the endocrine and nervous systems.
- Screen the heart. Echocardiography at intervals is used for survivors with high cumulative anthracycline or chest radiation exposure.
- Check endocrine axes. Thyroid function is checked after neck radiotherapy, and growth, cortisol and gonadal hormones are checked after childhood cranial irradiation.
- Counsel on fertility. Fertility preservation is discussed before treatment where possible, and contraception and pregnancy risks are reviewed afterwards.
- Watch for second cancers. Screening follows age and the irradiated field, and breast screening may be advised after chest irradiation at a young age.
Where the exam tries to catch you
Questions test whether a late effect is linked to the drug or field that caused it, rather than only to the cancer.
- Trap: Anthracycline cardiotoxicity appears only during treatment. Correct: it can appear years later, so survivors need long-term cardiac surveillance.
- Trap: Therapy-related AML is treated exactly like de novo AML. Correct: it often carries adverse cytogenetics and a poorer response, so the workup and expectations differ.
- Trap: Radiation fields do not matter for late effects. Correct: the organs inside a field determine which late effects appear, such as the thyroid after neck radiotherapy.
Frequently asked questions
Which chemotherapy drug causes dose-related cardiomyopathy as a late effect?
Anthracyclines such as doxorubicin cause dose-related cardiomyopathy, and the risk rises steeply with cumulative dose. Mediastinal radiotherapy adds to this risk, so it is considered when planning long-term cardiac follow-up.
Which treatments cause secondary acute myeloid leukaemia?
Alkylating agents, topoisomerase II inhibitors and radiotherapy are linked to therapy-related acute myeloid leukaemia and myelodysplastic syndrome. Therapy-related leukaemia often carries adverse cytogenetic features and a poorer response.
How does cancer therapy cause infertility in survivors?
Alkylating agents, especially cyclophosphamide, and pelvic or abdominal radiotherapy damage the ovaries or testes and cause infertility. Fertility preservation is discussed before treatment where possible, and gonadotropin-releasing hormone agonists may protect ovarian function during chemotherapy.
Which endocrine deficiency follows neck radiotherapy?
Neck radiotherapy commonly causes hypothyroidism, which is why thyroid function is checked at intervals after treatment. Cranial irradiation in childhood separately causes growth hormone deficiency and hypothalamic-pituitary axis failure.
Which chemotherapy drug causes pulmonary fibrosis as a late effect?
Bleomycin causes pneumonitis and pulmonary fibrosis, and the risk is increased by chest radiotherapy and high inspired oxygen. Pulmonary function tests and clinical review help detect the injury early.