Impact of radiotherapy on bone health in women with rectal cancer – A prospective cohort study

Pelvic radiotherapy (RT) increases the risk of pelvic insufficiency fractures. The aim was to investigate if RT is associated with changes in serum bone biomarkers in women with rectal cancer, and to examine the incidence of radiation-induced bone injuries and the association with bone biomarkers. Women diagnosed with rectal cancer stage I-III, planned for abdominal surgery ± preoperative (chemo) RT, were prospectively included and followed one year. Serum bone biomarkers comprised sclerostin (regulatory of bone formation), CTX (resorption), BALP and PINP (formation). A subgroup was investigated with annual pelvic magnetic resonance imaging (MRI). The association between RT and bone biomarkers was explored in regression models. Of 134 included women, 104 had surgery with preoperative RT. The formation markers BALP and PINP increased from baseline to one year in the RT-exposed group (p