Haematological Malignancy

Haematological malignancies are cancers that affect the blood, bone marrow, lymph nodes, and the lymphatic system, representing the fifth most common cancer group in economically developed regions.

Table of contents

• What Are Haematological Malignancies?
• Main Types of Blood Cancers
• Classification and Organization
• How These Cancers Develop
• Diagnosing Haematological Malignancies
• Global Impact and Trends
• Treatment Approaches
• Living With Haematological Malignancy

What Are Haematological Malignancies?

Haematological malignancies are cancers that start in the blood-forming system of the body. These diseases affect how blood cells are produced and how they function^[3]. Unlike cancers that form solid tumors in organs, haematological malignancies are sometimes called liquid tumors because they involve cells that circulate through the blood and lymphatic system^[7].

Most of these cancers begin in the bone marrow, which is the soft, spongy center inside bones where blood is made^[3]. In your bone marrow, stem cells develop and mature into three main types of blood cells: red blood cells that carry oxygen, white blood cells that fight infections, and platelets that help blood clot^[3].

In haematological malignancies, the normal process of blood cell development is interrupted. Abnormal cells begin to grow in an uncontrolled way, preventing your blood from performing its essential functions like fighting infections or preventing serious bleeding^[3].

Main Types of Blood Cancers

There are three main categories of haematological malignancies, each affecting different parts of the blood and immune system^[3].

Leukemia

Leukemia is found in your blood and bone marrow. It is caused by the rapid production of abnormal white blood cells^[3]. These abnormal cells cannot fight infection properly, and they interfere with the bone marrow’s ability to produce healthy red blood cells and platelets. Leukemia can be acute (developing quickly) or chronic (developing more slowly)^[2].

Lymphoma

Lymphoma affects the lymphatic system, which is responsible for removing excess fluids from your body and producing immune cells^[3]. In lymphoma, a type of white blood cell called lymphocytes become abnormal. These cancerous cells multiply and collect in lymph nodes and other tissues throughout the body. Over time, they weaken your immune system^[3]. Lymphoma is divided into two main types: Hodgkin lymphoma and non-Hodgkin lymphoma^[3].

Myeloma

Myeloma is a cancer of plasma cells, which are white blood cells that produce antibodies to fight diseases and infections^[3]. When myeloma develops, these cancer cells prevent the normal production of antibodies, leaving your immune system weakened and making you more susceptible to infections^[3].

Classification and Organization

Haematological malignancies are traditionally organized by where the cancer is first detected: in the blood (leukemias), lymph nodes (lymphomas), or bone (myelomas)^[6]. However, modern medical classification uses a more detailed system developed by the World Health Organization that defines over 100 specific subtypes based on the presumed cell of origin, genetic abnormalities, and clinical features^[6].

These cancers can develop from two major blood cell families. Myeloid cancers develop from white blood cells called granulocytes and related cells in the bone marrow. Examples include acute myeloid leukemia, chronic myeloid leukemia, and myelodysplastic syndrome^[2]. Lymphoid cancers affect lymphocytes and include acute lymphoblastic leukemia, chronic lymphocytic leukemia, Hodgkin and non-Hodgkin lymphomas, and multiple myeloma^[2].

• Blood
• Bone marrow
• Lymph nodes
• Lymphatic system
• Spleen

hematologic malignancies, blood cancers, hematologic cancers, liquid tumors

How These Cancers Develop

Haematological malignancies occur when blood cells start to grow abnormally and uncontrollably. In many cases, chromosomal translocations—when pieces of chromosomes break off and attach to different chromosomes—are a common cause of these diseases^[7]. This is different from most solid tumors, where such genetic changes are less common.

The disease process varies depending on the specific type. For example, in acute myeloid leukemia, there is increased production of immature cells called blasts^[2]. Patients often present with bone marrow failure because these excessive blast cells disrupt normal blood cell production. This leads to pancytopenia, a condition where all types of blood cells are reduced^[2].

In chronic myeloid leukemia, the disease is defined by a specific genetic abnormality called the BCR-ABL1 fusion gene, which usually results from an exchange of genetic material between chromosomes 9 and 22, creating what is known as the Philadelphia chromosome^[2].

Diagnosing Haematological Malignancies

When haematological malignancy is suspected, doctors use several tests to confirm the diagnosis. The initial workup typically includes blood tests to check for abnormalities and to rule out medical emergencies^[2]. These tests include a complete blood count with differential (which shows the types and numbers of different blood cells), tests for electrolytes, calcium, phosphorus, and various other markers^[2].

A peripheral blood smear, where a drop of blood is examined under a microscope, can reveal abnormal cells^[2]. For definitive diagnosis, a bone marrow biopsy is often necessary. During this procedure, a small sample of bone marrow is removed and examined for cancer cells^[2].

Additional specialized tests may include flow cytometry, which identifies specific markers on cell surfaces, and cytogenetics, which looks for chromosomal abnormalities^[2]. If neurological symptoms are present, a lumbar puncture (spinal tap) may be performed to check if cancer has spread to the nervous system^[2].

Global Impact and Trends

Globally, new cases of haematological malignancies have been increasing since 1990, reaching approximately 1,344 thousand cases in 2019^[4]. However, death rates for all types of haematological malignancies have been declining over the past 30 years^[4].

The burden of these diseases varies by gender, age, region, and a country’s economic situation^[4]. Generally, haematological malignancies occur more frequently in men than in women^[4]. Among the different types, Hodgkin lymphoma has shown the most significant decline in death rates^[4].

Treatment Approaches

Treatment for haematological malignancies has advanced significantly in recent years. The specific treatment depends on the type of cancer, genetic characteristics of the cancer cells, and individual patient factors such as age and overall health^[2].

Chemotherapy

Chemotherapy uses drugs to kill cancer cells and remains a cornerstone of treatment^[2]. For acute myeloid leukemia, a common approach is called 7+3 therapy, which involves 7 days of one drug called cytarabine plus 3 days of another drug from a class called anthracyclines^[2]. Patients typically receive multiple rounds of chemotherapy, and the drugs are often given in combination^[10].

Targeted Therapies

Newer targeted therapies focus on specific characteristics of cancer cells while minimizing damage to normal cells^[8]. The number of targeted drugs approved has been significantly higher than traditional chemotherapy agents in recent years^[8]. These include small molecule inhibitors, monoclonal antibodies (which help the immune system recognize and attack cancer cells), and antibody-drug conjugates^[8].

Some targeted therapies combine chemotherapy with agents that encourage the body’s immune system to target cancer cells more effectively^[11]. This approach can kill more cancer cells while protecting normal cells from lasting side effects^[11].

Stem Cell Transplantation

Stem cell transplantation involves infusing healthy stem cells into a patient’s body after intensive treatment^[10]. The stem cells may be collected from the patient’s own blood, from a donor, or from umbilical cord blood^[10]. This procedure can offer the possibility of cure for some types of haematological malignancies, particularly chronic myeloid leukemia, though it carries significant risks^[2].

Immunotherapy

Immunotherapy works by harnessing the patient’s own immune system to fight cancer^[9]. Several categories of immunotherapy have been developed, including immune checkpoint inhibitors, tumor vaccines, and adoptive cell therapies such as CAR-T cells^[9]. These approaches have shown the potential to induce long-term remission in patients whose disease has returned or not responded to other treatments^[9].

Radiation Therapy

Radiation therapy uses high-energy x-rays to kill cancer cells and can also provide pain relief^[10]. It may be used alone or combined with other treatments such as stem cell transplantation^[10].

Living With Haematological Malignancy

Patients with haematological malignancies face unique challenges compared to those with solid tumors. These patients experience high rates of hospitalizations and intensive care unit admissions, and they often spend their final days in the hospital rather than at home or in hospice care^[15].

The physical and psychological burden is substantial. Patients endure immense symptoms from both their illness and often intensive treatments that result in significant side effects^[15]. Many patients also harbor misperceptions about treatment risks and benefits and may overestimate their prognosis^[15].

Lifestyle and Self-Care

Studies show that many patients make positive lifestyle changes after diagnosis, particularly regarding smoking, with significant reductions in smoking behavior observed^[21]. However, changes in diet and exercise habits are less consistent^[21].

Taking care of yourself during treatment is essential. This includes eating nutritious food, getting adequate rest, and engaging in activities that bring you joy when you feel able^[17]. Even maintaining small routines from before diagnosis can provide comfort and a sense of normalcy^[17].

Emotional Well-Being

The emotional impact of a haematological malignancy diagnosis can be overwhelming. Feelings of shock, fear, sadness, and confusion are completely normal^[17]. Mental health is just as important as physical health during this time, and many patients benefit from talking to counselors, therapists, or oncology social workers^[17].

Support Systems

You don’t have to face this journey alone. Surrounding yourself with supportive people—whether close friends, family members, support groups, or your healthcare team—can make a significant difference^[17]. Being honest about your feelings, needs, and concerns with both your care team and loved ones helps everyone provide better support^[17].

Survivorship

Even after successful treatment, survivors of haematological malignancies may struggle with late effects, post-treatment complications, and post-traumatic stress symptoms that can significantly diminish quality of life^[15]. Ongoing follow-up care and support are important for addressing these long-term challenges.

Research has shown that integrating palliative care services can improve quality of life and care for patients with haematological malignancies and their caregivers^[15]. These services focus not just on treating the disease but on managing symptoms, addressing emotional and spiritual needs, and supporting both patients and families throughout the illness journey.