More than 10 million people in the United States are living with cancer, a population of survivors that has tripled in size since 1970. Long-term survivors face increased risk of many health problems, including subsequent cancer, either by recurrence of their original disease or a new primary cancer.

A new analysis from scientists at the Division of Cancer Control and Population Sciences (DCCPS) used Surveillance, Epidemiology and End Results (SEER) data to develop what they believe is the first population-based estimate of the number of people living who have had a diagnosis of more than one primary cancer.

The current estimate puts the number of people in the United States diagnosed with more than 1 primary cancer at 756,467, which represents 8 percent of all those living with cancer, and 0.26 percent of the total U.S. population. The research was published in the March issue of Cancer Epidemiology Biomarkers & Prevention.

"It's important for clinicians to recognize that cancer survivors have the same or higher risks, compared to the general population, of developing another cancer and will require appropriate long-term medical surveillance," said Dr. Angela B. Mariotto, the first author in the DCCPS study. She advocates the development of treatments tailored for this uniquely vulnerable population, since treatment for the first cancer might limit what can be given when a new cancer is diagnosed.

In the near future "the number of multiple malignancies will almost surely increase," Dr. Mariotto predicted, as the baby boom generation reaches the age where cancer incidence rises and individuals diagnosed with cancer continue to live longer.

A recent monograph published by the Division of Cancer Epidemiology and Genetics and DCCPS also uses SEER data to quantify the site-specific risks of developing a secondary cancer. The results show which specific cancers are more likely to follow a first cancer, and that overall cancer survivors have a 14 percent higher risk of developing a new malignancy than would be expected in the general population.

A study in the March 21 Journal of the American Medical Association focused only on second cancers that developed in long-term survivors of acute lymphoblastic leukemia (ALL), the most common childhood cancer in the United States. Almost 4,000 cases are diagnosed each year, and currently more than 80 percent of these children are cured, using the criterion of no recurrent disease for 10 years.

Dr. Nobuko Hijiya from St. Jude Children's Research Hospital in Memphis and colleagues analyzed the records of 2,169 newly diagnosed ALL patients who participated in clinical trials at St. Jude between 1962 and 1998 and who achieved complete remission. After a median follow-up time of 18.7 years, 7.7 percent of survivors had developed secondary neoplasms. When the less aggressive cancers - basal cell carcinoma and meningioma - were excluded, the rate was 13.5 times greater than that of the general population.

After 15 years, 4.17 percent of ALL survivors had developed a second cancer. Previous studies had suggested the incidence of second cancers may level off after about 15 years, but the authors believe that much of these data were limited by relatively incomplete and short follow-up times. Cumulative incidence in the ALL study rose sharply after about 20 years and had not leveled off at 30 years, by which time it had reached 10.85 percent.

By Addison Greenwood