The American Cancer Society estimates that nearly than 120,000 people will be diagnosed with leukemias or lymphomas in 2011; however, the risk factors and causes of these diseases remain somewhat a mystery.

We spoke with Joseph Moore, MD, professor of hematology and oncology with the Duke Cancer Institute, about leukemias and lymphomas. Moore, a recognized leader in the treatment of malignant and non-malignant hematological disease, has been at Duke for more than 30 years.

What are leukemia and lymphoma?

People often think that leukemia and lymphoma are the names of two types of cancer. Actually, they encompass a diverse group of cancers -- liquid tumors that arise from cells in the blood, bone marrow, and the immune system.

There are four main types of leukemias: acute lymphocytic (ALL) and acute myeloid (AML) leukemias; and chronic lymphocytic (CLL) and chronic myeloid (CML) leukemias. The acute conditions occur at all ages and usually require immediate and aggressive treatment.

There are two general groups of malignant lymphomas: Hodgkins and non-Hodgkins lymphoma. Non-Hodgkins, which includes approximately 30 different clinical types, can be a misleading and confusing term.

There is often a misperception that because it contains the phrase “non,” the disease is not as harmful as Hodgkins. On the contrary, non-Hodgkins lymphomas are very serious. They can occur at any age, but the incidences increase with age.

In Hodgkins, most of the cases are found in those who are 15-40 years old or those older than 55.

For certain “low-grade” lymphomas and chronic lymphatic leukemia, physicians may choose to observe the patient rather than provide treatment initially. If the cancer progresses then treatment may be administered. When the disease is considered acute, aggressive and immediate medical attention is needed.

What are the symptoms?

A problem with these diseases is that the symptoms are often subtle or non-specific, such as fever, fatigue, and weight loss, and may mimic other conditions.

In some chronic leukemias, doctors may just happen to find it during routine blood work in patients with no symptoms. With lymphomas, there are often tumors on the lymph nodes around the body, which may be found during normal physical examinations. Blood and bone marrow tests help to confirm the disease.

What are the known risk factors?

Unfortunately, despite years of research, we still do not know why most people develop these diseases. Some patients develop acute myeloid leukemia because of exposure to chemicals, radon, or even chemotherapy. But these are still only a few of the cases.

Future studies will continue to investigate risk factors and determine why some people develop the diseases while others do not. Duke researchers currently are conducting a study involving families in which several members have chronic lymphatic leukemia to determine if there is a genetic or hereditary relationship.

Some patients with lymphomas already have HIV. This is because of a weakened immune system which makes lymphomas more likely to occur. Still, a majority of lymphoma patients do not suffer from another disease.

Also, in rare cases, those who had a solid organ transplant (heart, lung, liver, kidney) develop lymphomas because of the suppression of the immune system.

What are the available treatments?

There are a variety of options to treat these diseases such as chemotherapy, radiation, targeted therapy, surgery, immunotherapy, and bone marrow and stem cell transplantation.

Treatments have improved dramatically -- the relative five-year survival rate for leukemia has more than tripled in 45 years, going from 14 percent in the early 1960s to nearly 49 percent today. We are not done trying to improve these statistics.

Currently, many treatments have begun targeting signaling pathways and actual genetic abnormalities associated with cancer. In the future, I expect will we use more targeted therapies so that we can better attack the cancer with few side effects, both for leukemias and lymphomas as well as for other tumors. Many of these targeted therapies are in development at Duke.