Blood Cancer - Types, Symptoms, Causes, Diagnosis & Treatment

Blood cancer definition

Blood cancer refers to a group of diseases in which abnormal blood cells grow uncontrollably and interfere with the normal function of healthy blood cells. These cancers usually begin in the bone marrow, where blood is produced, and are also known as hematologic cancers. Common types of blood cancer such as leukemia, lymphoma, and multiple myeloma.

Blood cancer is associated with symptoms such as fatigue, frequent infections, unexplained bruising or bleeding, anemia, bone pain, swollen lymph nodes, weight loss, and weakness. It can be caused by genetic alterations in blood cells, exposure to certain chemicals or radiation, infections, or inherited risk factors.

Although blood cancer can be serious and, in some cases, chronic (long-term), treatments including chemotherapy, targeted therapy, radiation therapy, immunotherapy and stem cell transplantation can help manage the disease and improve patient outcomes.

Diagnosis and treatment are managed by a doctor, usually a hematologist or oncologist, using blood tests, bone marrow examinations, imaging studies, and genetic testing to confirm the type of blood cancer and guide appropriate treatment.

Blood cancers, including leukemia, lymphoma, and multiple myeloma, are a major global health burden. According to global cancer estimates from the International Agency for Research on Cancer and the World Health Organization, over 13 lakh new blood cancer cases are diagnosed worldwide each year, accounting for about 6–7% of all new cancers. Non-Hodgkin lymphoma is the most common type globally. The burden is rising due to population growth, ageing, improved diagnosis, and better survival.

Blood cancers, including leukemia, lymphoma, and multiple myeloma, are a significant and growing health burden in India. According to the International Agency for Research on Cancer (GLOBOCAN) and the World Health Organization, India reports around 1.2–1.3 lakh new blood cancer cases annually. These cancers account for 8–9% of cancers in men and 5–6% in women. Leukemia is most common in children and young adults, while non-Hodgkin lymphoma predominates in adults.

Blood cancers, also called hematologic cancers, affect the blood, bone marrow, and lymphatic system. They are mainly classified based on the type of blood cell affected. The primary types of blood cancers include:

• Leukemia
• Lymphoma
• Multiple Myeloma
• Myelodysplastic Syndromes (MDS)
• Myeloproliferative Neoplasms (MPN)

Leukemia is a cancer of the bone marrow and blood, where the body produces an excessive number of abnormal white blood cells that do not function properly. These abnormal cells crowd out healthy blood cells, leading to anemia, infections, and bleeding problems.

Subtypes of leukemia:

• Acute Lymphoblastic Leukemia (ALL): It rapidly progressing, and mainly affects children, involves lymphoid cells.
• Acute Myeloid Leukemia (AML): Rapid progression, more common in adults, involves myeloid cells.
• Chronic Lymphocytic Leukemia (CLL): Slowly progressing, usually in older adults, affects B lymphocytes.
• Chronic Myeloid Leukemia (CML): Slowly progressing, affects myeloid cells, often linked to the Philadelphia chromosome mutation.

Lymphoma is a cancer of the lymphatic system, which is part of the immune system. It mainly affects lymphocytes, a type of white blood cell.

Two main types of Lymphoma :

• Hodgkin Lymphoma (HL): Characterised by Reed-Sternberg cells; usually starts in lymph nodes and spreads in an orderly manner. Common in young adults (20–40 years).
• Non-Hodgkin Lymphoma (NHL): More common than HL, can involve B-cells or T-cells, spreads unpredictably, and may affect organs like the liver or bone marrow.

Multiple myeloma is a cancer of plasma cells, specialised B lymphocytes that produce antibodies. In this disease, abnormal plasma cells accumulate in the bone marrow, interfering with normal blood cell production and causing bone damage.

MDS is a group of disorders caused by abnormal development of blood cells in the bone marrow. The bone marrow produces immature or defective blood cells, which leads to low levels of healthy blood cells.

MPN is a group of blood cancers where the bone marrow produces too many blood cells, red cells, white cells, or platelets. Unlike leukemia, the cells are mature but abnormal in function.

Common types of Myeloproliferative Neoplasms (MPN):

• Polycythemia Vera (PV): Excess production of red blood cells.
• Essential Thrombocythemia (ET): Excess platelets.
• Primary Myelofibrosis (PMF): Scar tissue builds up in the bone marrow, leading to low blood counts and spleen enlargement.

Blood cancer symptoms vary based on the type. The most common symptoms to look for include abnormal blood counts, organ enlargement, and systemic illness. The following are the symptoms of blood cancer:

• Persistent fatigue and weakness
• Pallor and shortness of breath
• Unexplained weight loss
• Fever and recurrent infections
• Night sweats
• Easy bruising or bleeding (gum bleeding, nosebleeds, prolonged bleeding)
• Painless swelling of lymph nodes (neck, axilla, groin)
• Abdominal fullness or pain due to an enlarged liver or spleen
• Bone or joint pain
• Skin petechiae or rashes
• Headache or neurological symptoms in advanced stages

Persistent fatigue and weakness: Blood cancer reduces the number of healthy red blood cells, resulting in anemia. This makes everyday tasks exhausting and lowers overall stamina.

Pallor and shortness of breath: A lack of sufficient red blood cells makes the skin appear pale, and oxygen delivery to organs becomes inefficient. This can also make even small activities like climbing stairs feel difficult.

Unexplained weight loss: Cancer cells may consume nutrients intended for the body, and the disease can also affect appetite. Over time, this can lead to prominent and rapid weight loss.

Fever and recurrent infections: Low white blood cell (WBC) counts compromise the immune system, making the body vulnerable to bacteria and viruses. Recurrent infections or continuous fever are common warning signs.

Night sweats: These are often drenching and may soak clothing and bedding. They occur because the cancer affects hormone and immune responses, leading to issues with temperature regulation.

Easy bruising or bleeding (gum bleeding, nosebleeds, prolonged bleeding): With fewer platelets, minor injuries can lead to prolonged bleeding or large bruises. Even minor cuts can take much longer to stop bleeding.

Painless swelling of lymph nodes (neck, axilla, and groin): The accumulation of abnormal blood cells in lymph nodes causes swelling. Since it is often painless, it may go unnoticed until it becomes prominent.

Abdominal fullness or pain due to an enlarged liver or spleen: Enlargement of these organs can compress surrounding tissues. This can lead to discomfort, early satiety, or a feeling of abdominal pressure.

Bone or joint pain:  Cancer cells crowding the bone marrow increase pressure inside the bones. Pain is often dull, persistent, and may worsen at night or during activity.

Skin petechiae or rashes: These are tiny spots appear when blood leaks from capillaries under the skin. They can signal low platelet levels and often signal clotting problems.

Headache or neurological symptoms in advanced stages: If cancer spreads or affects blood flow in the brain, it can cause headaches, vision changes, numbness, or difficulty concentrating.

These are direct biological or medical factors that can lead to the development of blood cancers by causing permanent changes in blood-forming cells, resulting in abnormal cell growth, survival, and impaired normal blood cell production. Below are the causes of blood cancer:

• Genetic mutations
• Bone marrow disorders
• Viral infections
• Previous cancer treatment

Genetic mutations:  Acquired or inherited DNA changes cause uncontrolled growth and division of blood cells. These mutations may affect genes responsible for cell cycle control, DNA repair, or apoptosis, allowing abnormal cells to survive and multiply.

Bone marrow disorders: Conditions such as myelodysplastic syndrome disrupt normal blood cell production and promote abnormal cell growth. Over time, ineffective marrow function creates an environment where malignant blood cells can replace healthy cells.

Viral infections: Viruses like Epstein–Barr virus (EBV) and HTLV-1 interfere with normal blood cell regulation and trigger malignant transformation. Chronic viral infection can accelerate persistent immune activation and genetic instability, increasing cancer risk.

Previous cancer treatment: Chemotherapy or radiotherapy can damage bone marrow cells, leading to secondary blood cancers years later. The risk depends on the type, dose, and duration of treatment, as well as individual susceptibility.

Risk factors for blood cancer are conditions or exposures that increase the risk of developing the disease by affecting genes, the immune system, or the environment. While they rarely cause cancer on their own, they can raise susceptibility when combined with other factors:

• Radiation Exposure
• Chemical Exposure
• Immune System Problems
• Age
• Gender
• Lifestyle Factors (indirect)

Radiation Exposure: Therapeutic radiation and certain chemotherapy treatments can raise the incidence of subsequent blood malignancies, particularly acute myeloid leukemia, for many years following exposure.

Chemical Exposure: Long-term contact with carcinogenic chemicals like benzene, pesticides, or industrial toxins triggers chromosomal abnormalities in bone marrow. Benzene, which is commonly found in gasoline and solvents, shows dose-dependent links to acute myeloid leukemia in occupational and epidemiological studies.

Immune System Problems: Immunodeficiency states, including HIV infection, autoimmune disorders, or immunosuppression after organ transplant, impair surveillance against malignant clones. HIV-associated lymphomas arise from chronic B-cell stimulation by the virus.

Age: The incidence of many blood cancers increases with age, particularly in older adults, due to cumulative genetic damage and age-related changes in bone marrow function.

Gender:  Blood cancers are generally more common in men than in women. This may be due to differences in hormones, immune response, genetics, and environmental or occupational exposures, which can influence how blood cancers develop.

Lifestyle Factors (indirect): Smoking, obesity, and persistent exposure to hazardous substances may all raise the risk of blood cancer by causing inflammation, immunological dysregulation, and genetic damage.