Updated radiotracers marketed for use in cancer diagnosis and targeted therapies could carry substantial health risks for premenopausal women that aren’t echoed in men, three New York physicians reported in a Radiology editorial this month.
Radiation exposure from CTs, FDG PET and modern radiopharmaceuticals used for cancer diagnosis, staging and treatment pose an ongoing threat to imaging departments, first author Anat Biegon, PhD, and co-authors wrote. Those procedures have been linked to a theoretical increase in risk of developing secondary cancer—something researchers are actively trying to prevent.
“Recent development in CT dose-reduction techniques and the advent of PET/MR scanners have contributed to significant reductions or even elimination of radiation from CT and PET/MRI in diagnostic radiology,” Biegon, a professor of neurology at Stony Brook Neurosciences Institute in New York, and colleagues said. “This goal is harder to achieve in diagnostic and therapeutic nuclear medicine, in the clinical as well as the research setting, since these procedures involve systemic administration of radioactivity and minimizing non-target organ exposure.”
Women have historically been more vulnerable than men to radiation uptake during imaging, the authors said, “for reasons that are not entirely understood.” Some evidence suggests the phenomenon, which largely effects the ovaries, endometrium and breasts, might be partially owed to hormonal changes during the menstrual cycle, but current guidelines for dosimetry studies don’t require inclusion of women at specified hormonal states. That means scientists have lacked the information necessary to make a solid conclusion on the subject.
Biegon, alongside two colleagues at Stony Brook, conducted a study of men and both premenopausal and postmenopausal women to widen the existing body of research. Measuring radiation uptake mid-cycle and during women’s menstrual-early follicular phase, the researchers found that mean standardized uptake values and radiation exposure to the ovaries were three and 30 times higher, respectively, than in men or postmenopausal women. Even a conservative dose of radiation to the ovaries would likely exceed FDA limits, they said.
“The recent explosion in development of new radiotracers for cancer diagnosis and targeted therapy, many of which target biomolecules, which vary in abundance as a function of hormonal milieu, poses a disproportionate risk of adverse effects in women of reproductive age,” the authors wrote.
The team said including women of specific menstrual stages in clinical studies, as well as developing a fresh set of national radiotracer guidelines, could be a start to solving the problem.
“There is a need for new guidelines for radiotracer development and use, which, unlike some recently suggested guidelines, are evidence-based, sensitive and responsive to the greater risk to reproductive organs inherent in exposing reproductively competent women to administered radiopharmaceuticals,” Biegon and colleagues wrote. “Inclusion of women in defined hormonal states in dosimetry studies and recommending that both clinical and research nuclear medicine procedures on young women be performed in the least susceptible phase of the menstrual cycle could improve the safety and diagnostic accuracy of nuclear medicine procedures in women.”