MedWire News: A study of long-term survivors of childhood cancer suggests that such individuals have a fracture risk that is comparable to that of the general population.
The findings offer reassurance in light of the established bone-harming effects of chemotherapy and radiotherapy, although the researchers say that longer-term follow-up remains important.
Carmen Wilson (St Jude Children's Research Hospital, Memphis, Tennessee, USA) and team investigated long-term bone health among 7414 participants from the Childhood Cancer Survivor Study (cases) and 2374 cancer-free siblings (controls).
Case participants had been diagnosed with cancer in childhood between 1970 and 1986 and had survived for at least 5 years. The most common cancer diagnosis was leukemia, 43.6% of cases had received methotrexate, 42.0% had received prednisone, 30.8% had undergone cranial irradiation, and 13.1% had undergone pelvic irradiation.
The cancer survivors were assessed for bone health a median of 22.7 years after cancer diagnosis, when they were aged on average 36.2 years. Siblings were slightly older, averaging 38.1 years, at the time of assessment.
The prevalence of at least one lifetime fracture was 34.8% among cases and 38.9% among controls, a nonsignificant difference. In both cases and controls, the most frequent site for fracture was the upper limb, followed by the lower limb and skull.
After adjusting for a raft of potential confounders, male cancer survivors were significantly less likely to have a fracture than siblings (prevalence ratio 0.87). A similar trend was seen for female cancer survivors, although it did not reach statistical significance (prevalence ratio 0.94).
In multivariate analysis, increasing age at follow-up, White race, methotrexate treatment, and balance difficulties were each independently associated with an increased prevalence of fracture among female survivors.
Among male survivors, only smoking history and White race were associated with an increased prevalence of fracture.
"Overall, the findings from this study indicate that the prevalence of fracture among long-term adult survivors of childhood cancer is similar to that of their siblings despite chemotherapy and radiation exposure known to disrupt bone metabolism during therapy," write Wilson et al in Cancer.
"Nevertheless, caution is required when interpreting these results because the majority of study participants have yet to reach an age at which the underlying population risk of fracture increases substantially… Moving forward, it will be important to characterize long-term skeletal morbidities in postmenopausal and aging childhood cancer populations."
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