Prolymphocytic leukemias (PLLs) are rare lymphocytic leukemias. Like leukemia, PLLs affect the blood, bone marrow and spleen. PPLs are also like lymphomas because they start in the lymphocytes. PLLs are also considered lymphoproliferative disorders, which means that the bone marrow makes large numbers of lymphocytes.
With PLL, the abnormal lymphocytes are large, immature cells called prolymphocytes. These prolymphocytes are not normally found in the blood. Sometimes chronic lymphocytic leukemia (CLL) will change, or transform, and look like PLL. A diagnosis of PLL is made when at least 55% of the cells in the blood are prolymphocytes.
PLL often occurs in older people, usually in people between 65 and 70 years of age. It is slightly more common in men than in women.
PLL is divided into 2 types based on the type of lymphocyte that the PLL starts in.
B-cell prolymphocytic leukemia (B-PLL) accounts for about 80% of PLLs.
T-cell prolymphocytic leukemia (T-PLL) is usually faster-growing (more aggressive) than B-PLL.
A person with PLL usually has:
- a larger than normal spleen or liver
- a very high white blood cell count
- low red blood cell count (called anemia)
- low platelet count (called thrombocytopenia)
- B symptoms (unexplained fever, drenching night sweats and unexplained weight loss)
You may be offered the following treatments for PLL.
Watchful waiting (also called active surveillance) may be offered for PLL. The healthcare team will carefully monitor the person with PLL and start treatment when symptoms appear or there are signs that the disease is progressing more quickly.
Some combinations of chemotherapy drugs that may be used to treat PLL are:
- CVP – cyclophosphamide (Cytoxan, Procytox), vincristine (Oncovin) and prednisone
- CHOP – cyclophosphamide, doxorubicin (Adriamycin), vincristine and prednisone
Other chemotherapy drugs that may be used to treat PLL include:
- fludarabine (Fludara)
- cladribine (Leustatin)
- pentostatin (deoxycoformycin, Nipent)
Targeted therapy uses drugs to target specific molecules (such as proteins) on the surface of cancer cells. These molecules help send signals that tell cells to grow or divide. By targeting these molecules, the drugs stop the growth and spread of cancer cells while limiting harm to normal cells.
The following targeted therapy drugs may be used alone or in combination with chemotherapy to treat PLL that no longer responds to chemotherapy.
- rituximab (Rituxan) for B-PLL
- alemtuzumab (Campath) for T-PLL
Surgery to remove the spleen (called a splenectomy) may be offered for PLL. It is done to improve red blood cell or platelet counts. It is also done to relieve discomfort if the larger than normal spleen puts pressure on other organs.
When a splenectomy is not an option, external beam radiation therapy to the spleen may be used to treat PLL.
I’m extremely grateful to the Canadian Cancer Society for funding my research with an Innovation Grant.
Great progress has been made
Some cancers, such as thyroid and testicular, have survival rates of over 90%. Other cancers, such as pancreatic, brain and esophageal, continue to have very low survival rates.