Juvenile myelomonocytic leukaemiacancer of blood and/or blood forming tissues (JMML) is a very rare type of childhood bloodthe red bodily fluid that transports oxygen and other nutrients around the body cancera disease where abnormal cells split without control and spread to other nearby body tissue and/or organs that is caused by an overproduction of immature white blood cellsthe basic structural and functional unit of all living things (WBCs) in the blood and bone marrowsoft, spongy tissue found in bones that makes blood cells. More specifically, it causes an overproduction of monocytes, which is the largest type of WBC in the blood that can develop into either a macrophage (ingest and degrade dead cells, debris, tumoura tissue mass that forms from groups of unhealthy cells cells and/or foreign substances) or a dendritic cell (initiate and regular the adaptive immune response).
Blood is the bodily fluid of the circulatory system that provides nutrients and oxygen to our tissues, and helps to remove waste from our bodies. There are three primary types of blood cells produced in the inner, spongy portion of the bone (bone marrow) from stem cells (immature blood cells that develop into either red blood cells (RBCs), white blood cells (WBCs), or plateletssmall disc-shaped blood cells that clump together to form clots to stop bleeding). RBCs, or erythrocytes, are responsible for providing oxygen to the tissues in our body, as well as transporting carbon dioxide to the lungs to be exhaled. WBCs are responsible for fighting infectiona condition where harmful pathogens, such as bacteria, viruses or parasites, have entered the body and disease in the body. Platelets are blood cells that play a major role in blood clotting (or coagulation), which is an important process that helps reduce blood loss after injury.
JMML is classified as a mix of myelodysplastic syndromes (MDS) and myeloproliferative syndromes (MPN), as it shares characteristics of both. For more information on MDS or MPN, please refer to the Rare Cancers Australia Myelodysplastic Syndrome (MDS) page or the Myeloproliferative Neoplasms (MPN) page.
JMML is slightly more common in males, and tends to be diagnosed in children under four. However, anyone can develop this disease.
Treatment
When cancers are detected, they are staged and graded based on size, metastasiswhen the cancer has spread to other parts of the body, also known as mets, and how the cancer cells look under the microscope. Stagingthe process of determining how big the cancer is, where it started and if it has spread to other areas and grading helps your doctors determine the best treatment for you. However, because of how rare JMMLs are, there is currently no standard staging and grading system for this disease. Instead of staging and grading, your doctor will recommend a treatment plan based on the following factors:
- Symptoms.
- Age.
- General health.
Treatment preferences.
Your doctor may recommend genetic testinga procedure that analyses DNA to identify changes in genes, chromosomes and proteins, which can be used to analyse tumour DNA to help determine which treatment has the greatest chance of success, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. Your doctor will discuss the most appropriate course of treatment for you.
Treatment options for JMML may include:
- Stem cell transplanta procedure that involves replacing unhealthy blood-forming cells (stem cells) with healthy stem cells.
- Chemotherapya cancer treatment that uses drugs to kill or slow the growth of cancer cells, while minimising damage to healthy cells.
- Clinical trialsresearch studies performed to test new treatments, tests or procedures and evaluate their effectiveness on various diseases.
- Palliative carea variety of practices and exercises used to provide pain relief and improve quality of life without curing the disease.
Risk factors
While the cause of JMML remains unknown, some of the following factors may increase the likelihood of developing the disease:
- Genetic mutations, potentially including:
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- NF1
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- PTPN11
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- CBL
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- RAS.
- Having genetic conditions such as:
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- Noonan syndrome.
Not everyone with these riskthe possibility that something bad will happen factors will develop the disease, and some people who have the disease may have none of these risk factors. See your general practitioner (GP) if you are concerned.
Symptoms
JMML may appear asymptomatic during the early stages of disease. As the cancer progresses, some of the following symptoms may appear:
- Anaemiaa condition where there aren't enough red blood cells in the blood, causing fatigue, weakness and pale skin and affecting how the body responds to infection, with symptoms potentially including:
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- Fatiguea state of extreme tiredness or exhaustion, can be physical or mental.
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- Dizziness.
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- Weakness.
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- Dyspneadifficulty breathing, shortness of breath.
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- Paleness.
- Neutropeniaa condition where there are low levels of neutrophils (a type of white blood cell) in the body, with symptoms potentially including:
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- Recurrent infections.
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- Fevers.
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- Mouth ulcers.
- Thrombocytopenialow levels of platelets in the blood, with symptoms potentially including:
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- Easy bruising.
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- Purpura or petechiaea rash of small, red dots due to small superficial capillary bleeds; generally smaller than purpura.
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- Bleeding of the nose and/or the gums.
- Unexplained weight loss/loss of appetite.
- Developmental delay.
- Failure to thrive.
- Irritability.
- Fever.
- Fatigue.
- Frequent and/or persistent infections.
- Easy bleeding and/or bruising.
- Splenomegalyenlargement of the spleen.
- Hepatomegalyenlargement of the liver.
- Lymphadenopathyswollen lymph nodes/glands, also known as adenopathy.
- Dyspnea.
- Skin lesions.
Not everyone with the symptoms above will have cancer, but see your general practitioner (GP) if you are concerned.
Diagnosis
If your doctor suspects you have an JMML, they may order the following tests to confirm the diagnosisthe process of identifying a disease based on signs and symptoms, patient history and medical test results and refer you to a specialist for treatment:
- Physical examinationan examination of your current symptoms, affected area(s) and overall medical history.
- Blood teststesting done to measure the levels of certain substances in the blood.
- Bone marrow aspirationa procedure that involves inserting a needle into the hipbone (or the breastbone in some cases) to remove samples of solid and liquid bone marrow.