NEW ORLEANSPediatric cancer survivors face an
increased risk of second malignancies later in life, especially breast cancer,
according to a large database of some 14,000 persons diagnosed with cancer
before age 21 and alive 5 years or longer.
About one out of 1,000 persons 20 to 30 years old is a survivor
of childhood cancer. More than two thirds of childhood cancers are being cured,
resulting in long-term survivorship with unknown consequences, said Joseph
Neglia, MD, associate professor of pediatrics, University of Minnesota,
Minneapolis.
The study, presented at the 92nd Annual Meeting of the American
Association for Cancer Research, is one of the largest retrospective studies to
focus on the risk of second malignancies in persons successfully treated for
cancer as children. The database comes from 25 centers in the United States and
Canada.
The study found 314 invasive cancers among 298 individuals. The
most common form of newly diagnosed cancer was breast cancer, accounting for 60
of the new cases, followed by thyroid cancer (43) and brain tumors (36).
These figures amount to a sixfold increase in the incidence of
new cancers over what would be expected in the general population, Dr. Neglia
reported.
For breast cancer, however, the increase was 16-fold. Contrary
to current belief, there was no association between age at treatment and risk.
Prepubertal and teenaged girls who were treated with chest irradiation were at
higher risk for breast cancer than has been commonly believed, as previous
studies found an elevated risk only among girls who had already reached puberty
when treated for cancer.
While the sixfold risk for second cancers seems high, Dr.
Neglia pointed out that this translates into only 1.8 excess cases of cancer
per 1,000 years of follow-up. "If you follow 100 people for 10 years,
fewer than two new cancers occur. In other words, people treated for cancer as
children are at increased risk for second cancers, though this risk is very
small in contrast with the remarkable benefits of their cancer therapy,"
he stressed.
The highest risk occurred in patients treated for Hodgkin’s
disease, particularly with radiotherapy; however, this amounted to only about
five excess cancers per 1,000 years of follow-up. Further, he said, since
aggressive radiotherapy is no longer standard for Hodgkin’s disease, children
treated today presumably have a lower risk of second malignancies than was seen
in this study.
Dr. Neglia suggested that childhood cancer survivors require
greater surveillance and should be engaged in discussions with their physicians
about their possible risks. For instance, women treated with irradiation as
children should consider beginning mammography screening as early as their 20s,
he said.
Oncologists need to modify treatment regimens to reduce
patients’ risk for second cancers without compromising efficacy, he further
suggested. Many pediatric oncology centers are already reducing the use of
certain chemotherapeutic agents known to increase secondary cancer risk, and
new methodologies for reducing irradiation are being employed.
Marriage Study
A related report, from the Childhood Cancer Survivor Study,
found that survivors of central nervous system (CNS) malignancies, particularly
males, were less likely to marry than survivors of other cancer diagnoses or
the general US population. The study included 1,477 subjects, who were found to
have a fourfold increased likelihood of never marrying.
The type of treatment was significantly associated with the
odds of marrying, especially among males, said Amanda M. Rauck, MD, of Columbus
Children’s Hospital, Ohio State University.
Surgery alone, surgery plus irradiation, and surgery plus
irradiation and chemotherapy accounted for 98% of the treatment of these
patients. Only 7.5% of the CNS tumor survivors receiving the trimodality
therapy reported having married (4% of males and 12% of females), compared with
36% of those treated surgically (26% of males and 48% of females) and 25% of
those treated with surgery and irradiation (20% of males and 30% of females).
More females than males in each group reported getting married
(P = .0001), and age at diagnosis was not associated with marital status, Dr.
Rauck said.
