Trial Information

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.