Blood cancers

Haematological malignancies(blood cancers)are cancers that arise and affect blood forming cells in the bone marrow. They affect  patients across all age groups,although the prognosis tends to be better in much younger individuals.

Not much is known about the cause of these malignancies,though previous exposure to radiation, even in utero, and some drugs ,have been put forward as possible causes,among others. Although there is a lot that  it still not known with regards the actual cause, genetic aberrations remain the main driving force behind these cancers and govern the choice of therapy.

There are two main types of haematological cancers, namely “Acute” and “Chronic”. The former is more aggressive,and occurs mainly in the younger population (younger than 20),although there is a subtype of acute leukemia that does arise in patients around 50 years of age.”Chronic” leukaemias tend to progress much slower,affect older individuals, and are rarely life threatening. The focus of this article will  mainly be on the “acute” type of  leukaemias.

The classification of these cancers is based primarily on their cells of origin in the bone marrow and their genetic characteristics. These factors have both treatment and prognostic implications and will be taken into account when planning an approach to therapy.

Symptoms of blood cancer include easy fatigability,susceptibility to infections and easy bruising. This relates to infiltration of bone marrow by cancer cells/clones,with subsequent replacement of normal bone marrow elements by cancer cells.
Fatigue is a result of anemia(decrease in Hemoglobin content,which is the protein that gives blood the red colour and allows red cells to carry and transport oxygen necessary for vital functions.)

In the same vein,susceptibility to infections is as a result of a decrease in white cells which are responsible for assisting our bodies in fighting off infections.
Any of these symptoms should prompt a visit to a medical practitioner,who will draw the relevant blood samples and submit them for analysis.
It is also worthwhile to remember that there may be other,less ominous explanations for fatigue and susceptibility to infections, like stress and other non life threatening diseases of the immune system.

In the unfortunate event of a suspicious blood count you will be required to undergo a bone marrow aspiration .This provides more detailed information about the type and extent of the cancer,as well as allows for assessment of the genetic signature of the tumour,helpful for treatment planning and prognostication.
It is at this stage that you will be referred to an oncologist or a haematologist  for initiation of treatment.

Here are the general treatment principles that of course will differ slightly from patient to patient based on the cancer subtype.

Chemotherapy

This is the mainstay of treatment. It is aimed at eradicating the cancer cells in the marrow and peripheral blood and allowing for recovery of normal bone marrow cells.
The major limitation of this treatment is side effects,coupled with a fairly prolonged hospital stay.Hair loss,mouth ulcers,diarrhoea,abdominal cramps and infections are but some of the side effects that may be experienced in relation to the treatment. However these are, by and large effectively treated,emphasising the importance of being treated in a dedicated haematology-oncology unit.
Whereas the chemotherapy aims to eradicate cancer cells it inevitably affects normal cells as well, as a “bystander” effect. This results in your normal counts declining significantly soon after treatment. Thankfully,normal bone marrow cells do recover function over the few weeks following chemotherapy.

Supportive care

It is during this time of marrow insufficiency that supportive treatment will be administered as appropriate in the form of  blood and platelet transfusions and growth factors to aid white cell count recovery,if deemed necessary. Infections are actively sought and aggressively treated,whilst  close contact with other people is kept to a minimum, as the immune system becomes susceptible to even the most trivial of infections.

Bone marrow transplant

Once the chemotherapy has been completed and depending on the specific type of cancer and its molecular signature,you may need a bone marrow transplant.
There are two distinct types of bone marrow transplants. The first is where doctors use your own blood(stem cells) to carry out the transplant,after eradicating as much disease as possible.This allows higher than normal doses(up to ten times the normal dose) of chemotherapy to be administered while using your own stem cells as “rescue” from the anticipated bone marrow suppression. This is called an autologous transplant and a donor is not needed as you are the “donor”.

Another type of bone marrow transplant is an “allogeneic” transplant where a donor is needed to provide stem cells. The main aim of this procedure is to use the immune cells of the donor to eradicate cancer cells in the recepient.Whereas in the past donors needed to donate actual bone marrow samples,with recent medical advances, donors today are only required to donate peripheral blood from which stem cells are harvested.Donors are usually siblings but in the event that none of the siblings’s blood match ,a search in the local and international bone marrow registries is undertaken.

This emphasises the all important need for the public to sign up as donors with the local registry. The South African Bone Marrow registry is in acute need of donors especially  those of African descent as reflected by the difficulties in locating donors especially for this group of patients. At present the registry has  approximately 60000 donors,and only 2.4%  of these are African.This has the undesirable consequence of patients failing to get a match and inevitably succumbing to the disease.

Ongoing clinical research continues to provide much needed insights into the management of haematological malignancies.It remains a challenge for the medical and civil society to cooperate in finding solutions and improving outcomes for patients suffering from these and other cancers.

For more information about the South African bone marrow registry and other relevant organisations for this course, visit:
www.sabmr.co.za
www.sunflowerfund.org.za