30 Nov 2024

Research Blog: Back to Basics

This month for our research blog, we are going back to basics and exploring what makes leukaemia fundamentally different from other types of cancer. Cancer is an umbrella term for diseases caused by the uncontrolled growth of abnormal cells, leukaemia stands apart primarily because of its circulating throughout the body from the onset of disease. This distinction shapes not only how leukaemia develops and spreads but also how it is diagnosed, treated, and experienced by patients.

Unlike solid tumours, which grow as localised masses in organs like the lungs, breasts, or colon, leukaemia does not form a lump or a detectable structure. Instead, it originates in the bone marrow, where blood cells are produced, and involves the overproduction of abnormal white blood cells. These cells flood the bloodstream and disrupt the delicate balance of healthy blood cell production. Because the circulatory system connects to every part of the body, leukaemia has a systemic impact from the start. This characteristic sets it apart from many other cancers, which often remain confined to a single site until they metastasise. This also means other cancers can be referred to in stages e.g. stage 1: where a tumour is small and localised. Leukaemia however does not have a stage as its cells circulate throughout the whole body. Another key difference is that certain subtypes of leukaemia often involve the overproduction of immature, undifferentiated cells, whereas most other cancers typically result in the overproduction of mature cells. This distinction highlights how leukaemia directly disrupts the normal development and function of blood cells, impairing the body’s ability to fight infections, carry oxygen, and form clots. This leads to the symptoms of leukaemia being so varied and wide spread, from bone and muscle pain to infections to fatigue.

Diagnosing leukaemia also reflects its unique nature. While imaging technologies like CT scans and MRI are key tools in detecting solid tumours, leukaemia is usually identified through blood tests. A full blood count (FBC) often reveals abnormally high or low levels of white blood cells, red blood cells, or platelets, prompting further investigation. A bone marrow biopsy is then used to confirm the presence of leukaemia cells. Usually, genetic and molecular testing is also performed to understand the specific mutations driving the disease. For example, chronic myeloid leukaemia (CML) is closely associated with the Philadelphia chromosome, a genetic abnormality that has become a target for tailored therapies.

Another key difference is the approach taken to treatment of leukaemia compared to solid tumours. These commonly follow similar steps, starting with surgery or chemotherapy combined with surgery once the tumour has shrunk, this can be followed by systemic anti-cancer therapies (SACT) and radiotherapy. In the treatment of leukaemia surgery is not an option, instead treatment often relies on chemotherapy to irradiate nearly all leukaemia cells, often followed by a stem cell transplant. However, much like other cancers, leukaemia treatment is moving into an era of personalised medicine and options include more specifically tailored treatment approached, such as targeting specific genetic mutations or antigens.

Another key difference lies in the way leukaemia progresses. Acute forms of leukaemia, such as acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML), develop rapidly and can become life-threatening within weeks if not treated promptly. These aggressive forms require immediate intervention, often with high-dose chemotherapy. In contrast, chronic leukaemia types, like chronic lymphocytic leukaemia (CLL) and CML, tend to progress more slowly and may remain asymptomatic for years. In some cases, patients with chronic leukaemia are closely monitored without immediate treatment, an approach known as “watch and wait.” This variability in progression highlights the complexity of leukaemia compared to many other cancers, which often follow more predictable growth patterns, even with aggressive forms.

Leukaemia also differs in its age distribution. Acute lymphoblastic leukaemia is the most common cancer in children, while chronic forms of leukaemia typically affect older adults. This dual age prevalence underscores the diverse nature of the disease and the need for tailored approaches to treatment and care.

Ultimately, what sets leukaemia apart is its systemic nature and its profound impact on the blood and immune systems. While other cancers may begin in one place and spread over time, leukaemia disrupts the body’s equilibrium from the very beginning. This poses unique challenges but also opens doors for innovative treatments that harness the immune system or target genetic mutations, such as the rising star of treatments: CAR-T therapy. Interestingly, overlap in some of the molecular mechanisms driving different cancers has meant that pioneering advances in leukaemia treatments, have been applied to other cancer types. Conversely, newer targeted therapies being developed for other cancers are also benefiting leukaemia treatment efforts. Understanding these differences and connections not only helps us better support patients but also drives research efforts to improve outcomes and, one day, achieve cures for all forms of leukaemia.

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