Prevention of Osteoporosis in Breast Cancer Survivors

Each year, more than 192,200 women are diagnosed with breast cancer (Greenlee, Hill-Harmon, Murray, & Thun, 2001). With an increase in early detection and improved therapies, more of these women have become survivors (Vassilopoulou-Sellin & Theriault, 1994). However, many of these women are at increased risk for osteoporosis and the debilitating consequences. This increased risk occurs for two reasons. Over 50-70% of women under the age of 50 (premenopausal) who are treated with adjuvant chemotherapy experience ovarian failure and early menopause (Ali & Twibel, 1994; Cobleigh et al., 1994; Samaan et al., 1978), resulting in a long postmenopausal period of estrogen deprivation. Breast cancer survivors also are at greater risk for osteoporosis because they usually are not candidates for hormone replacement therapy (HRT). Estrogen can influence the growth of cancer in women, especially those with estrogen receptor positive tumors (ER+), and at least 60% of women have ER+ breast cancer (DeVita, Hellman & Rosenberg, 1997). While the use of HRT significantly reduces osteoporosis and the risk of forearm, vertebral, pelvic, and hip fractures in postmenopausal women (Cobleigh et al., 1994; Finkelstein, 1996), women with a history of breast cancer generally are not considered candidates for HRT. Without estrogen, women may lose up to 30% of their bone mass within the first 5-years postmenopause, with continued bone loss over time, but at a slower rate. Very little information has been reported on the incidence and treatment of osteoporosis in breast cancer survivors (Headley et al., 1998; Hosking et al., 1998).

Osteoporosis is a major risk factor for chronic disability and especially hip fractures. The majority of individuals with hip fractures never return to prefracture functional status and estimates of health care costs for individuals with osteoporosis exceed the costs for those with congestive heart failure or with asthma (U.S. Congress Office of Technology Assessment, 1994; Ray, Chan, Thamer & Meltin, 1997). Prevention and treatment of osteoporosis, by increasing bone mineral density (BMD) and muscle strength, may decrease the chronic disabilities associated with osteoporosis and improve quality and quantity of life (Mahon, 1998). Research on effective alternatives to HRT for the prevention of osteoporosis in breast cancer survivors has been targeted as a priority area by the Office of Cancer Survivorship (Division of Cancer Control and Population Sciences) at the National Cancer Institute (Office of Cancer Survivorship, 1999). No reports were found in which the effectiveness of the combination of risedronate, calcium, and vitamin D (administered together and at the current recommended levels for postmenopausal women) was studied, nor has the effectiveness of the addition of long term progressive strength/weight training exercises been evaluated in this at risk population of breast cancer survivors.