"The observed hazard ratio for radiation therapy in women with anal cancer was 3.16. This value can be interpreted as a 3-fold increase in pelvic fracture risk for women with anal cancer who underwent radiation therapy (vs. women who did not) at any given time. The observed hazard ratio for radiation therapy in women with cervical cancer was 1.66; in women with rectal cancer, 1.65. These values indicate a lesser effect, but are still consistent with a substantial increase in fracture risk," the researchers write.
"Given the high baseline rate of fractures in women aged 65 years or older, the hazard ratio of 1.65 that we found in our study may represent an increased lifetime incidence of fractures from the baseline rate of 17 percent to 27 percent a substantial and clinically significant absolute increase."
"The high risk of pelvic fracture after radiation therapy for anal cancer may reflect the radiation therapy technique used to treat this disease. In the treatment of anal cancer, it is usually appropriate to treat the inguinal [pertaining to the groin] nodes because of the risk of disease at this site. Because of the location of these nodes with respect to the femoral head and neck, it has been difficult to treat these nodes well without concomitant irradiation of the femur, and thus the femoral heads are exposed to a relatively high irradiation dose in the treatment of anal cancer patients," the authors write.
The researchers add that it is important to note that the study population (older, predominantly white women) was already at hig
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