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Many individuals have annual medical checkups and are put at ease once their blood work comes back as "normal." The presumption in many cases is that a normal CBC translates into no risk for having cancer. It is true that blood tests are useful and very important diagnostic methods, however, in some cases blood cancer might be present even when blood work looks normal on routine testing. It does not mean that blood tests should be considered unreliable. It is important to consider the overall clinical context including symptoms, physical exam findings, imaging studies, special tests in addition to blood work.
What Is CBC And What Information Does It Give?
CBC stands for Complete Blood Count. This is the test that evaluates how many red blood cells, white blood cells and platelets are circulating in your blood vessels. Usually, this test is ordered as the first one to evaluate fatigue, fever, infections, bleeding. Blood cancer, especially leukemia, can manifest through abnormal CBC findings. Indeed, even the National Cancer Institute admits that cancer can be present in individuals despite the normal laboratory values, and a blood test cannot diagnose cancer or exclude it.
If It Is Blood Cancer, Then How Is It Possible To Be Present In A Patient With Normal Blood Values?
It is important to know that blood cancers are a group of disorders. Leukemia, lymphoma, multiple myeloma, and a number of others belong to this group and they are characterized by different manifestations. Thus for instance, a lymphoma usually starts developing in the lymph nodes but not in the circulating blood cells. During the early stage, it does not affect blood cell counts. Several studies prove that many patients with lymphoma, including those suffering from an aggressive type of the disease, have normal CBC. So, a normal blood test result can never be used as a basis for excluding lymphoma.
Some leukemias during the early stage of development do not cause any changes in the blood cell counts as well.
Symptoms Are Just As Important As Tests
One of the most common errors made by patients is ignoring symptoms because their blood report came out "normal".
If any of the following occur, see a doctor:
- Persistent fatigue that does not go away with rest
- Frequent fever or infections
- Unexplained weight loss
- Sweating at night
- Bruising and bleeding easily
- Swelling of the lymph nodes in the neck, armpit, or groin
- Unexplained pain in bones and joints
- Unexplained difficulty breathing
The above symptoms are not necessarily indicative of cancer. In India, the symptoms may be due to infections, deficiencies of certain nutrients, or diseases like tuberculosis. But the point here is that when one experiences these symptoms, they need to be evaluated even if one's normal blood report says otherwise.
What Is Done When There Is A Suspicion Of Blood Cancer?
In case symptoms, examination, or imaging suggest any suspicion of blood cancer, then doctors might suggest more tests to be done. Tests such as peripheral blood smear, specific blood test, ultrasound/CT scan, lymph node biopsy, or bone marrow test can be suggested. A biopsy will help in getting the final diagnosis as the biopsy allows doctors to look at the cells directly.
The idea is not to conduct lots of tests in all individuals, but to rule out possible symptoms which are ignored due to normality of a particular test.
Indian Perspective
There is a rising incidence of cancers, including blood cancers in India. Regrettably, most patients come in late due to the fact that early symptoms are thought to be related to stress, weakness, infection, or ageing, leading to a normal health check report. However, what needs to be remembered is that having a normal blood test is a relief, but there can never be a 100% guarantee of absence of a type of blood cancer. If there are any symptoms or signs that keep occurring, they should be checked out.
It is important to take blood tests routinely but it is just the start of the whole diagnosis process. Your body will give you many signs if something goes wrong with it. Therefore, it should be taken into account.
(By Dr Asma Pathan | Cancer Physician | M|O|C Cancer Care Pune)
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