A disease so lazy it rarely proves fatal
Jasmine Chan, 55, was a healthy individual with no physical complaints. So when a routine health check in 2008 revealed that she had a type of blood cancer rarely seen in Asians, it caught her and doctors by surprise.
A complete blood count test showed Chan (whose real name is withheld for reasons of patient confidentiality) had a level of lymphocytes - a type of white blood cell responsible for killing bacteria and viruses - that was abnormally high. Chan's blood test showed that she had some 10 times the normal level. Although high levels can be the result of infections, Chan's lack of symptoms and extremely high lymphocyte levels alerted doctors that a blood disorder was present.
When Dr Raymond Liang Hin-suen, director of the Comprehensive Oncology Centre at the Hong Kong Sanatorium and Hospital, analysed Chan's lymphocytes under the microscope, he saw that the cells were mature, thereby ruling out acute leukaemia, which creates abnormal looking, immature white blood cells. Instead, chronic lymphocytic leukaemia (CLL) was a likelier fit, but the condition usually strikes Caucasians over 60 years old. Relatively young and Asian, Chan was an unusual candidate.
To confirm his suspicions, Liang ordered two tests: an immunophenotyping test which uses monoclonal antibodies (made in a lab rather than a person's own immune system) to identify and characterise the problematic lymphocytes, and a bone marrow test to investigate the extent of the suspected leukaemia.
Both tests confirmed the condition. Chan's bone marrow had a large number of abnormal lymphocytes, which were circulating in her blood and also affected her lymph nodes, spleen and other organs. Eventually, the cancer will cause her bone marrow to fail, thereby reducing her blood count and weakening her immune system.
While a cancer diagnosis usually strikes dread in the hearts of people, CLL sufferers often have less to fear from this disease than other health conditions. An indolent (inactive or relatively benign) disease, it usually progresses so slowly that elderly patients often succumb to other health conditions before CLL becomes a fatal threat, says Liang. However, Chan was relatively young and otherwise healthy. Hence, Liang had to exercise extra caution in dealing with the cancer.
Liang's next task was to anticipate how the cancer was going to behave, and he did so using a cytogenetic test that looks at the changes to the chromosomes inside the leukaemia cells. Specific changes to the cells, such as the absence of certain parts of the chromosomes, are reliable predictors of how aggressive the cancer will be and even how well the patient may respond to treatment.
In Chan's case, the cytogenetic tests showed that the cancer did not appear to be fast moving and posed no immediate threat. Moreover, she had no symptoms. Liang decided that treatment was not necessary at that time. Chan was monitored closely via quarterly blood tests.
Two years after the diagnosis, Chan's blood tests showed that the lymphocyte levels were rising faster than before and her lymph glands started to enlarge rapidly. At that point, Liang decided it was time to take action.
Chan was given a cocktail of chemotherapy drugs and steroids, which reduced the population of abnormal lymphocytes and reduced the swelling in her lymph glands.
Liang says that although it will be several years before Chan will need further treatment, she has a higher risk of infection and must be vigilant about her health. In the meantime, she has returned to work and her normal life, carrying the mixed blessing that is a slothful blood cancer.