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Treatment and the treatment process

What happens at relapse

Relapse is the return of leukemia after remission. When it happens, the team reassesses the situation and builds a new plan.

Last updated: ~2 min read
On a dark navy background, among calm teal and gold healthy cells, a few small red cells reappear at one edge.
Figure 1.At relapse, hidden cells appear again.

01Short answer

Relapse means leukemia cells that could not be seen after treatment have started to grow again. It may be found in blood tests, in the bone marrow, sometimes only in MRD tests ("molecular relapse"), and rarely outside the marrow — in the spinal fluid, testes or skin. When relapse is suspected, a bone marrow test and genetic tests are usually repeated, because leukemia cells can gain new mutations. The team then weighs several factors: when the relapse happened (early or late), previous treatment, genetic features, overall health and your own wishes. Options include further chemotherapy, targeted drugs, immunotherapy (such as antibodies or CAR-T), stem cell transplant, or clinical trials.

02Simple explanation

A return. Hidden cells grow again.

Confirmation. Bone marrow and genetic tests are repeated.

Reassessment. The team considers every factor.

A new plan. There may be several treatment paths.

03Scientific explanation

Types of relapse: haematological (blasts rising again in the marrow), molecular or MRD relapse (seen only on sensitive tests), and extramedullary (CNS, testis, skin). The length of remission is an important prognostic sign: early relapse usually points to more resistant disease.

Clonal evolution: at relapse, mutations may appear or disappear (such as FLT3 and IDH1/2 in AML, or ABL1 kinase domain mutations in CML), so a repeat genetic profile is needed to choose targeted drugs. In B-ALL, CD19 or CD22 expression affects the choice of immunotherapy.

Treatment principles: the aim is often to regain remission and, where suitable, proceed to allogeneic transplant; for relapse after transplant, reducing immunosuppression, donor lymphocyte infusion or a second transplant may be considered. Palliative support can be offered alongside at any stage.

04What happens in the body?

Why does relapse happen?

Even the most sensitive tests cannot find every cell. A small number of cells that survive treatment can grow again over time.

Several paths

Treatment after relapse is personal. The team should openly discuss the benefits and risks of each path with you.

On a dark background, a softly glowing crossroads with paths of light leading in different directions.
Figure 2.After relapse there may be several treatment paths.

Support matters

This news brings strong feelings. Talking with family, friends, a psychologist and patient organisations can lighten the load.

In lamplight, two pairs of hands hold warm cups of tea across a small table, faces not shown.
Figure 3.Support and conversation help carry hard news.

05Steps after relapse

A simplified outline.

Confirmation — Bone marrow.1ConfirmationBone marrow.
Genetic tests — New features.2Genetic testsNew features.
Team discussion — All options.3Team discussionAll options.
A new plan — Made together with you.4A new planMade together with you.
Remission againOften the aim.
Targeted choiceBased on genetics.
SupportAt every stage.

06Possible options after relapse

OptionExampleNote
ChemotherapyRe-inductionDepends on previous treatment
Targeted drugsFLT3, IDH, BCR-ABL inhibitorsBased on genetic results
ImmunotherapyAntibodies, CAR-TMainly ALL and some other types
TransplantAllogeneicAfter remission, if suitable
Clinical trialNew medicinesDepends on the centre
Palliative supportSymptom controlAlongside, at any stage

* Only your treating team, together with you, decides which option fits.

07Key terms

Relapse
Return of disease after remission.
Molecular relapse
Disease seen only on sensitive tests.
Extramedullary
Outside the bone marrow.
Clonal evolution
New changes arising in leukemia cells.
CAR-T
Treatment with specially prepared T cells.
Second opinion
The view of another specialist.

08Key points

  • Relapse is hard news, but there are options.
  • Relapse is confirmed with repeat tests.
  • Genetic tests can open new paths.
  • The plan is personal and made together.
  • You have the right to a second opinion.
  • Emotional support is part of treatment.

09Frequently asked questions

Is relapse my fault?

No. Relapse comes from the biology of the leukemia cells, not from anything you did or didn’t do.

Is remission possible again?

In many cases yes; your doctor will give you specific information about your chances.

How can I join a clinical trial?

Ask your doctor about suitable trials; sometimes referral to another centre is needed.

How do I tell my children?

Simple, honest, age-appropriate words are advised; a psychologist can help.

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. Is relapse my fault?

  2. Is remission possible again?

  3. How can I join a clinical trial?

  4. How do I tell my children?

My questions

12Sources

  1. National Cancer Institute (NCI). Adult Acute Myeloid Leukemia Treatment (PDQ) – Patient Version
  2. National Cancer Institute (NCI). Adult Acute Lymphoblastic Leukemia Treatment (PDQ) – Patient Version
  3. National Cancer Institute (NCI). Definition of relapse – NCI Dictionary of Cancer Terms
  4. National Cancer Institute (NCI). Follow-Up Medical Care
  5. American Cancer Society. Treating Acute Myeloid Leukemia (AML)
  6. Cancer Research UK. Treatment for acute lymphoblastic leukaemia (ALL)
  7. NHS. Acute lymphoblastic leukaemia: Treatment
  8. Leukemia & Lymphoma Society. ALL treatment
  9. Cancer Research UK. Types of acute lymphoblastic leukaemia (ALL)
  10. Leukemia & Lymphoma Society. ALL subtypes
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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