In fact, the investigators found, “In women younger than age 60 years, pelvic radiation decreased survival and increased the risk of secondary cancer. “
They point out that most women with endometrial cancer survive for a long time, but there is evidence of increased risk of secondary cancers after radiation therapy.
The current findings come from a long-term follow-up of outcomes in the Norwegian Radium Hospital trial in which 568 patients with stage I endometrial cancer were randomized to receive adjuvant vaginal brachytherapy with or without subsequent external beam radiation therapy (EBRT).
Dr. Kristina Lindemann, at Oslo University Hospital, and colleagues found that median overall survival was not significantly different in the two arms: 20.50 years in the EBRT group and 20.48 years in the control group (p=0.186), which translated to a mortality hazard ratio of 1.13.
However, when patients were stratified by age, the mortality risk in women younger than 60 years at diagnosis was significantly higher with EBRT than without (hazard ratio 1.36), according to the report in the Journal of Clinical Oncology online September 9.
Regarding secondary cancers, the risk was significantly higher among women in the EBRT group than the control group (HR 1.42). Moreover, the risk was doubled among women younger than 60 at diagnosis who underwent EBRT (HR 2.02), the authors found.
“Because of its toxicity, EBRT should, in our opinion, be used only if there is clear evidence of a benefit in survival. So far, this has not been shown for any subgroup of endometrial cancer,” Dr. Lindemann and colleagues advise.
“Because EBRT increases the risk of secondary cancer, EBRT should certainly be used with caution, especially in younger women with long life expectancy,” they conclude.