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After treatment and remission

Risk of a second cancer

Some people who survive leukaemia develop a different, new cancer years later. This topic calmly explains what this risk depends on, how large it is and which checks help.

Last updated: ~3 min read
A lighthouse shining over a calm sea.
Figure 1.Long-term follow-up means staying alert.

01Short answer

A second cancer is not the return of the original leukaemia (relapse) but a completely new cancer. Its risk rises somewhat after some treatments, but most survivors never develop a second cancer. The risk depends mainly on three factors. Radiation: brain tumours after cranial radiation, thyroid cancer after neck radiation (topic “Thyroid”), and skin, breast, thyroid and other cancers after total body irradiation; these usually arise in the radiation field and years later (often more than 10 years). Chemotherapy: alkylating medicines and topoisomerase inhibitors (such as etoposide) can rarely cause a second leukaemia or myelodysplastic syndrome; this usually happens in the first years after treatment. Transplant and chronic GVHD: the risk of mouth and skin cancer rises (topic “Chronic GVHD”). Inherited tendency and lifestyle (tobacco, sun) also play a part. The COG recommends risk-based screening: a yearly skin and neck check, early breast screening for women who had chest radiation, and other tests if needed.

02Simple explanation

A second cancer is a new cancer, not a relapse.

The risk is small; most never get one.

Main factors: radiation, some chemotherapy, transplant.

Radiation-related cancers: years later, in the radiation field.

Help: risk-based screening, a healthy lifestyle.

03Scientific explanation

Radiation: according to the NCI, radiation-related second cancers (skin, thyroid, breast, brain) usually arise in the radiation field, and the risk rises with dose, young age and time since treatment.

Chemotherapy: the NCI and ACS note a risk of second AML and myelodysplastic syndrome after alkylating medicines and topoisomerase II inhibitors; it is rare and usually occurs within the first 10 years.

Transplant: according to the NCI, total body irradiation and chronic GVHD raise the risk of solid tumours after transplant, especially mouth and skin cancer.

Screening: the COG recommends risk-based checks — for example, yearly breast MRI and mammography for women who had chest radiation, starting at age 25 or 8 years after radiation.

04What happens in the body?

What is a second cancer?

It is a new, different cancer that develops after the first leukaemia. It does not mean the leukaemia has come back.

A small group of cells found in a circle of attention.
Figure 2.Finding changes early matters.

What affects the risk?

The site and dose of radiation, some chemotherapy medicines (alkylating medicines, etoposide), transplant, inherited tendency and lifestyle.

When might it appear?

A second leukaemia usually appears in the first years after treatment; radiation-related solid tumours more often after 10 years or more.

Which checks help?

Depending on risk: a yearly skin and neck check, early breast screening for women who had chest radiation, blood tests and other tests if needed. Your doctor sets the schedule.

What can lower the risk?

Not smoking, limiting alcohol, sun protection, physical activity, a healthy weight and keeping to your check-up schedule.

A shield of leaf, shade and path symbols.
Figure 3.Healthy habits lower the risk.

When to call your doctor

Worrying signs — fever, bleeding, new pain, breathlessness — should be reported to your doctor between visits too. Getting in touch early is always better than waiting.

05Staying alert to second cancers

Steps.

Know — Keep your treatment summary.1KnowKeep your treatment summary.
Screen — Follow the schedule.2ScreenFollow the schedule.
Check — Check your skin and neck.3CheckCheck your skin and neck.
Live well — Smoke-free, sun-safe.4Live wellSmoke-free, sun-safe.
Early detectionChanges are found early.
ProtectionRisk is lowered.
Peace of mindThe plan is clear.

06Second cancer: factors and checks (simplified)

FactorPossible riskCheck
Cranial radiationBrain tumoursNeurological check, MRI if symptoms
Neck radiation, total body irradiationThyroid cancerNeck examination
Chest radiationBreast cancerEarly breast screening
Alkylating medicines, etoposideSecond leukaemia (rare)Blood tests
Transplant, chronic GVHDMouth and skin cancerSkin and mouth checks

* Your doctor sets your own schedule.

07Key terms

Second cancer
A new cancer that arises after the first one.
Relapse
The return of the same cancer.
Screening
Checking before any signs appear.
Myelodysplastic syndrome
A condition where the bone marrow does not make blood cells properly.
Alkylating medicine
A type of chemotherapy medicine.
Radiation field
The part of the body that received radiation.

08Key points

  • A second cancer is not a relapse.
  • The risk is usually small.
  • Keep your treatment summary.
  • Follow your screening schedule.
  • Stay away from tobacco.
  • Report new signs.

09Frequently asked questions

What is my risk?

It depends on the treatment you had; your doctor can explain your own risk.

Can a second cancer be prevented?

The risk cannot be removed completely, but a healthy lifestyle and checks lower it and help find changes early.

Which signs should I watch for?

A new lump, a sore that does not heal, a changing spot on the skin, or unexplained weight loss or tiredness.

Are my children at risk too?

Usually not; if an inherited syndrome is suspected, genetic counselling helps.

Does this information replace medical advice?

No. This is general education; only your treating doctor can assess your situation.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. What is my risk?

  2. Can a second cancer be prevented?

  3. Which signs should I watch for?

  4. Are my children at risk too?

  5. Does this information replace medical advice?

My questions

12Sources

  1. Children's Oncology Group. Long-Term Follow-Up Guidelines for Survivors of Childhood, Adolescent and Young Adult Cancers
  2. National Cancer Institute. Late Effects of Treatment for Childhood Cancer (PDQ®)
  3. American Cancer Society. Second Cancers in Adults
  4. National Cancer Institute (NCI). Late Effects of Treatment for Childhood Cancer (PDQ®)–Patient Version
  5. National Cancer Institute. Stem Cell Transplants in Cancer Treatment
  6. National Cancer Institute (NCI). Follow-Up Medical Care
  7. National Cancer Institute (NCI). Cancer Survivorship
  8. Cancer.Net (ASCO). Follow-Up Care After Cancer Treatment
  9. Leukemia & Lymphoma Society (LLS). Long-Term and Late Effects of Treatment
  10. National Cancer Institute. Facing Forward: Life After Cancer Treatment
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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