Does prostate cancer increase the risk of osteoporosis?

The authors aimed to evaluate the association between prostate cancer and osteoporosis.

Androgen deprivation therapy (reducing the production of the male hormone, testosterone, or inhibiting its growth effect on cancer cells) is the favored treatment for recurrent and/or metastatic prostate cancer, and a significant proportion of patients will undergo some form of hormone therapy. While usually successful, androgen deprivation therapy can have side effects, including a potential decline in bone mineral density (the amount of mineral matter per square centimeter of bones). This is of concern as osteoporosis (bones become brittle and fragile from loss of tissue) and bone fractures negatively impact not only quality of life but also overall survival.  By contrast, a number of studies report a high prevalence of osteoporosis in patients before receiving androgen deprivation therapy.

The purpose of the present study was to determine whether the presence of prostate cancer is associated with a decrease in bone mineral density and to identify the factors associated with osteoporosis in patients diagnosed with prostate cancer before the initiation of any kind of treatment.

The medical records of 582 patients with prostate cancer and 2,536 healthy (control) patients were evaluated. For patients in the prostate cancer group, bone mineral density was measured within 2-4 weeks after diagnosis and before any therapy was initiated. For healthy men in the control group bone mineral density was measured as part of routine health care.

9.4% of the prostate cancer group had osteoporosis compared to 3.4% of the control group.  25.7% of the prostate cancer group had ostopenia (protein and mineral content of bone tissue is reduced but less severely than osteoporosis) compared to 27.7% of the control group. Osteoporosis was found in 25.5% of those prostate cancer patients presenting with bone metastasis (spread of cancer to the bone) compared to 8.5% of those without bone metastasis. Ostopenia was found in 21.3% of those prostate cancer patients presenting with bone metastasis compared to 25% of those without bone metastasis.

Those with prostate cancer were 2.96 times more likely to have osteoporosis compared to those without.  When variables that could affect bone mineral density, such as age, testosterone levels in the blood, body mass index, diabetes, high blood pressure and smoking were accounted for, those with prostate cancer were 3.22 times more likely to have osteoporosis. Bone metastasis was found to be an independent predictor of osteoporosis, with these patients 3.45 times more likely to have osteoporosis than those without bone metastasis.

The authors concluded that prostate cancer was a risk factor for osteoporosis.