Despite the significant progress that has occurred in recent decades in the treatment of many advanced malignancies, skeletal morbidity remains a major problem for patients affected by cancers that metastasize to or grow primarily within bone. Thus as patients with a variety of malignancies survive longer, therapies to limit cancer-associated as well as treatment-associated skeletal complications have become increasingly important for the provision of optimal patient care.
In addition to the direct effects of primary tumors in bone, bone complications in cancer patients occur from metastasis to bone and through the effects of cancer-related treatments and conditions. Bone is a very common metastatic site for many cancers, including myeloma, melanoma, and breast, prostate, thyroid, lung, bladder, and kidney cancers. Metastatic bone lesions can be osteolytic (bone destruction resulting from increased bone resorption and reduced formation), osteoblastic (increased bone formation), or both.
Bone renewal is essential for bone strength. During childhood and early adulthood, bone formation prevails over bone resorption, as bones increase in size and strength. Peak bone mass is achieved during the third decade in life, with a higher peak bone mass being protective against osteoporosis later in life. Bone loss is most prominent in women at menopause due to the effects of a natural decline in estrogen levels. However, bone mass begins to decrease with age, and bone loss is most prominent in women at menopause due to the effects of a natural decline in estrogen levels.
Over 40 million men and women in the United States have osteoporosis and low bone mineral density (BMD), placing them at risk for adverse skeletal events such as fractures and their sequelae. There are over 12 million cancer survivors in this country. Of these, 22% were diagnosed with breast cancer and 17% with prostate cancer.[1,2] Because cancer therapies can adversely influence bone health, these survivors are at particular risk for skeletal complications. Cancer therapies associated with bone loss include hormone deprivation therapies such as aromatase inhibitors, ablative surgical procedures that induce hypogonadal states, and premature menopause induced by chemotherapy.[3,4]