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Letter to the editor

Guest column

Secondary cancers in leukemia

By V. UPENDER RAO
Published May 9, 2005

Chronic lymphocytic leukemia is the most common form of leukemia in the western world. It usually manifests itself in the sixth decade but can affect younger patients also. Prognosis varies with the stage of the disease.

Until the advent of monoclonal antibodies, a complete remission in the bone marrow was not possible. Because chronic lymphocytic leukemia primarily affects the elderly, aggressive diagnosis and treatment are not always perused. Initially, patients respond well to a variety of drugs such as alkylating agents, purine analogs and monoclonal antibodies.

Although survival rates have improved with modern treatments, second malignancies are still a concern. The older literature suggests an excess of second cancers in these patients.

To examine the overall risk of second cancers, researchers at the M.D. Anderson Cancer Center studied 1,069 CLL patients between 1985 and 2001. At a mean follow-up of six years, 6 percent of patients were found to have developed a second cancer. The average time to develop the second cancer was 4.7 years, although it ranged from one to 16 years.

The likelihood of developing a second cancer was 17 percent for patients older than 70 and only 7 percent for those younger than 60. However, when compared with age-matched controls from the Connecticut Tumor Registry of patients who did not have CLL, there was no evidence of excess cancers in the CLL patients.

When considered by specific types of cancer, some important trends were discovered. CLL patients older than 60 were found to have a five times greater risk of developing malignant melanoma, usually within the first five years of diagnosis. There was an excess risk of Hodgkin's disease in all ages, but the older patients had a 23-fold- and the younger patients a 14-fold-greater risk compared to age-matched controls without a diagnosis of CLL.

There was a ninefold excess risk of acute myelogenous leukemias in men with CLL unrelated to age. Most of these patients with AML had previous treatment with Chlorambucil, an alkylating agent.

Overall, this analysis negated the older dogma that patients with CLL carried an excess risk of second cancers, but it yielded important information regarding specific malignancies on which screening can be focused. For instance, melanoma if diagnosed in early stages, can be surgically cured. The emergence of AML can be minimized by avoiding Chlorambucil. Most oncologists today use a purine analogue named Fluderabine, which is not known to be associated with AML.

At the Cancer and Blood Disease Center, we will be disseminating this information to our CLL patients and to the staff with the intent of raising awareness leading to regular screening, early diagnosis and possibly some cures.

--V. Upender Rao, MD, FACP, practices at the Cancer and Blood Disease Center in Lecanto.

[Last modified May 9, 2005, 01:54:14]