Susan Sontag: writer, intellectual, activist, National Book Award recipient, died December 28, 2004.

Bruno Kirby: actor, Pete Clemenza of "The Godfather Part II," died August 14, 2006.

Leukemia knows no profession, age, gender, race, or economic status. It can inflict anyone, anytime, anywhere. About 31,000 each year, 2,566 every month, 592 each week, 84 a day, 3 each hour are the numbers to speak for leukemia's prevalence -- at least, in America.

Leukemia is among the many deadly cancer types. Leukemia is a cancer that affects the blood or the marrow of the bone. This cancer type is characterized by the overproduction of certain blood cells, most common of which is the white blood cells or leukocytes. When there is an overproduction of white blood cells in the bone marrow, the regular amount of red blood cells, white blood cells, and platelets are being outnumbered and the blood gets a hard time to do its normal functions.

A leukemia case may be classified as either in the chronic stage or acute stage. Chronic leukemia is the stage when the unnecessary blood cells are still able to perform their normal function. Chronic leukemia commonly occurs among older people. Since leukemia at this stage does not show any sign or symptom, it is often undetected and eventually gets worse and reach the acute stage. A leukemia that reached the acute stage is already a harmful case. Here, the production is really way above the normal rate and the unnecessary blood cells do not perform their normal functions anymore. Acute leukemia is very common among children. It is actually known as among the leading causes of death among American children.

Leukemia has four known types: the chronic lymphocytic leukemia, acute lymphocytic leukemia, chronic myeloid leukemia, and acute myeloid leukemia. A leukemia is lymphocitic, if the lymphoid cells and myeloid cells are affected. Chronic lymphocytic leukemia is most common among adults above 55 years of age. This kind is almost non-existent among children, and accounts for about 7,000 cases each year. Acute lymphocytic leukemia, on the contrary, is most common among children and very rare among adults. The number of new acute lymphocytic leukemia cases total to about 3,800 every year. The estimate of chronic myeloid leukemia is at 4,400 new cases annually and is mainly affecting adults; on the other hand, acute myeloid leukemia is at a higher number at 10,600 count each year.

As with other cancer types, the causes of leukemia is still unknown. The closest the medical field has gone in determining the root cause of leukemia is the identification of risk factors or the things that increase the probability of one developing the disease. First and common to all cancer types is genetic influence. People with relatives who had any cancer type, died or survived, are at a very high risk level of having leukemia. Environmental factors, such as high radiation exposure and contact with carcinogenic materials, are also high risk factors. Exposure to chemicals and substance, such as benzene and formaldehyde, in the workplace or in other places also increases the risk of having leukemia. Medical conditions such as chemotherapy from a previous cancer, Down syndrome, and myelodysplastic syndrome are also known risk factors.

The most common symptoms of leukemia are flu-like ailments like fever and chills, bleeding and swollen gums, enlargement of spleen and liver, fatigue and frequent weakness, anemia, loss of weight, poor appetite, swollen lymph nodes, pain in joints and/or bones, and abdominal pains. However, these signs are not exclusive to leukemia alone. The safest way to confirm a possible leukemia case is through medical tests.

The treatment for leukemia is dependent on each particular case. But the most common treatment options are chemotherapy, radiation therapy, bone marrow transplantation, biological therapy, or surgery for cases with enlarged spleen. As may be required in special cases, a combination of the possible treatments can be administered. Patients suffering from acute leukemia need to be treated right away to mitigate the spread of cancer cells and the damages they may cause. Patients suffering from chronic leukemia, on the other hand, may not be in urgent need of a treatment, especially if there are no symptoms persisting. After any treatment, patients are highly encouraged to undergo post-traumatic care or supportive care for emotional and psychological conditioning.