Sex hormone-binding globulin linked to bone loss in prostate cancer
MedWire News: High sex hormone-binding globulin (SHBG) levels are significantly associated with low bone mass and vertebral fractures among patients with prostate cancer, Spanish researchers report.
These findings suggest that SHBG plays a major role in bone metabolism in patients with prostate cancer, say Manuel Muñoz-Torres (Hospital Universitario San Cecilio, Granada) and colleagues in Osteoporosis International.
They explain that prostate cancer patients, especially those on androgen-deprivation therapy (ADT), have an increased risk for fracture. Whether this increased risk is associated with levels of sex hormones or SHBG - a plasma glycoprotein that binds with high affinity to sex hormones - is unknown.
To investigate, Muñoz-Torres and team measured serum levels of SHBG, estrogen, androgens, bone mineral density (BMD), and the prevalence of radiographic vertebral fractures in 91 men (mean age 70 years) with prostate cancer, 49 of whom received ADT.
Of the patients, 19 (20.9%) had osteoporosis according to World Health Organization (WHO) criteria and 13 (13.6%) had prevalent vertebral fractures.
The researchers report that SHBG levels were significantly inversely related to BMD at the femoral neck and total hip.
SHBG levels were significantly higher in patients with osteoporosis than in those without it (61.0 vs 44.5 nmol/L), and were significantly higher in patients with prevalent vertebral fractures than in those without (63.1 vs 45.7 nmol/L)
Patients with SHBG levels in the highest quartile (>57.6 nmol/L) were a significant 2.6 times more likely to have osteoporosis and 2.3 times more likely to have a prevalent vertebral fracture than patients with lower SHBG levels.
The relationships were stronger after adjustment for age, estrogen and androgen levels, and duration of ADT, with the odds ratio for osteoporosis at the total hip among patients in the highest quartile versus lower quartiles reaching 21.2 in the androgen-adjusted model.
This finding indicates that SHBG "exerts a direct action on bone metabolism" and may be "a useful new marker of osteoporosis and vertebral fracture risk" in this patients with prostate cancer, Muñoz-Torres et al remark.
"In clinical practice, the measurement of serum SHBG may, therefore, help to predict the severity of osteoporosis in these patients," they conclude.
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By Laura Cowen