Is leukaemia a cancer? What organ does it affect?
Leukaemia is a cancer of the blood. It is a fluid cancer, also known as a liquid tumour.
Cancer cells are found within the blood, which is actually the biggest "organ" in the body as it affects the entire body.
The cancer starts in the bone marrow, the soft tissue inside the bones where blood cells are made.
The bone marrow produces white blood cells, red blood cells and platelets.
White blood cells protect from infection. If red blood cells are low, you get anaemic and start to feel tired. Platelets aid in blood clotting and stop bleeding.
When leukaemia strikes, the process of blood production is affected. Unlike other cancers, there are no stages in leukaemia as it usually doesn't spread to the other organs but stays within the blood system.
How does the disease present itself? What are the symptoms?
Patients experience symptoms affected to low blood counts. For example, they may be tired, prone to infection, bruise easily and experience excessive bleeding from cuts or frequent nose bleeds.
Many patients who come to me are just feeling tired. They may even be very fit.
For example, a patient may be used to running 4 km per day, then, gradually over a couple of weeks, he finds that he can only run 2 km. So he sees his general practitioner and a blood test finds that his blood counts are low.
Such cases are then referred to haematologists, like me, for more detailed blood tests and we may pick up the leukaemia. These patients are actually the lucky ones, where presentation is gradual.
On the other hand, we do get patients who come to the A&E (Accident and Emergency department) with acute leukaemia in a very dramatic fashion. Such cases are one of the most serious medical emergencies for oncologists. In those patients, the immune system can be extremely low.
Older patients, in particular, tend to be admitted with serious, potentially life-threatening infections because their immune system could be completely gone. Some are so sick that we can't even offer treatment.
If untreated, particularly for older patients, the progression and deterioration may be a matter of weeks, not even months.
When I was working in the UK previously, for example, a patient who was above 60 years old and had no treatment had a median survival rate of just two to three weeks.
Does it affect mainly older patients, then?
No, acute leukaemia is, in fact, the most common cancer among children. The peak incidence age is between two and eight.
The good news is, that today, Singapore has one of the highest cure rates for childhood leukaemia, with 80-90 per cent of children diagnosed with acute leukaemia cured with treatment. This is a highly encouraging number.
Unfortunately, leukaemia is much more challenging to treat when it affects adults. The disease tends to be more aggressive and the cure rate for middle-aged adults hovers around 50 per cent.
Why do people get leukaemia and how is it treated?
We still don't know why people get leukaemia.
Exposure to radiation is one of the known causes, and genetic disorders such as Down's syndrome tend to increase the odds, but in most cases, there are no identifiable causes.
The numbers at a glance
2,000 new cases per year
In Singapore, there are about 2,000 new cases of blood cancers, including leukaemia and lymphoma, every year, with at least six new patients diagnosed every day.
40% of patients get leukaemia
40 per cent of childhood cancer patients suffer from leukaemia, making it the most common cancer among children. The cure rate, for childhood leukaemia, however, is promising; 80-90 per cent of those diagnosed with acute leukaemia are cured.
1 in 4 chance of match
If a bone marrow transplant is required, there is a one in four chance of a tissue match among siblings. For unrelated persons, there is a 1 in 20,000 chance of finding a matching donor.
55,000 bone marrow donors
55,000 people have signed up as bone marrow donors so far, and the Bone Marrow Donor Programme (BMDP) in Singapore hopes to recruit at least 20,000 new donors over the next three years, or about 8,000 donors per year.
Chemotherapy is still the most effective treatment for leukaemia and other blood cancers, and patients may require two to three months of intensive chemotherapy to clear the cancer cells.
These days, chemotherapy drugs are more sophisticated with fewer side effects and complications.
However, in patients with a more aggressive disease, chemotherapy may not be enough. In such cases, a bone marrow transplant is the best chance for a cure. This simply means replacing the abnormal cancerous cells with healthy cells from a donor's bone marrow.
Finding a match, unfortunately, is not easy. There is a one in four chance that your siblings will be the right tissue match, but with smaller families nowadays, the odds are longer, that is, more unlikely.
Luck plays a part, too. There are cases where patients have up to 10 siblings and still cannot find a tissue match.
In such cases, we turn to the local bone marrow donor registry, and therefore, the more people willing to sign up as bone marrow donors, the higher the chances.
What about stem cell transplants?
The bone marrow is, in fact, a form of stem cell transplant with healthy bone marrow cells taken to replace the unhealthy leukaemia marrow cells.
In recent years, however, other forms of stem cell transplants are increasingly seen as a "magic pill".
These include haploidentical stem cell transplants, where only a 50 per cent tissue match is necessary. A transplant could also be autologous (from the patient's own stem cells) or allogenic (stem cells come from a donor).
However, while there is much excitement about the potential, there are also many misconceptions, and such transplants are not ready for widespread mainstream treatment currently and may not suit every patient.
In the coming years, however, it is likely that more will benefit from such stem cell transplants.
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