Leukemia in Patients With Cancer of the Cervix Uteri Treated With Radiation. A Report Covering the First 5 Years of an International Study

Summary

A prospective study of patients exposed to radiotherapy for cervical cancer was conducted. Patients under observation were seen twice a year during the first 5 years after diagnosis and annually after the first 5 years. Peripheral blood studies were made at each visit. An accumulated total of 60,000 person-years was assembled from 29 collaborating radiotherapy centers. Four cases of leukemia were reported in exposed patients, including 2 myelocytic and 2 lymphocytic cell types. These numbers and cell types did not differ significantly from expected numbers for a general population of females of the age group studied. A comparison group of cervical cancer patients who did not receive radiotherapy has been followed according to the same protocol and has accumulated 6,000 person-years, with one case of leukemia observed, of lymphocytic cell type. Leukemia incidences for the total population studied and for various subgroups defined by type of therapy and by interval after radiation exposure were all compatible with general population rates. For patients at risk in the interval 4–8 years after exposure, a fivefold increased risk could be excluded, but a fourfold increased risk remained possible. For patients exposed to combined external therapy plus intracavitary radium, observed at all intervals after exposure, a threefold increase was excluded.