Bone loss is associated with aging and long-term aromatase inhibitor treatment for breast cancer. As such, postmenopausal breast cancer survivors (PBCS) are at increased risk for fragility fractures and require screening, prevention, and treatment of osteoporosis. In this study, we evaluated the factors associated with osteoporosis knowledge, health beliefs, and preventive behaviors in postmenopausal women with early stage breast cancer. The majority of patients (80%) were receiving hormone therapy in the form of aromatase inhibitor, and 83% of patients had received a bone density scan within the last six years. Osteoporosis knowledge was low among this population, with average score of 10.5 out of a maximum of 20. Participants did not perceive that they were susceptible to osteoporosis and did not perform weight-training exercises regularly. Although most participants were adherent to calcium/vitamin D supplements, they had very low dietary calcium intake.
We found that participants, who were not married, had less than a high school education, or lower monthly income were less knowledgeable about osteoporosis. These results are consistent with previously reported studies in postmenopausal women [25–27] and PBCS [12, 28]. Interestingly, 80% of our participants knew that bone loss normally speeds up after menopause. However, we did not observe an association between receipt of bone density or bone density scores with osteoporosis knowledge. This suggests that the information obtained from bone density screening may not translate sufficiently to knowledge about osteoporosis or osteoporosis preventive behaviors. The lack of association was demonstrated in other studies showing that postmenopausal women who received bone density screening had insufficient knowledge about osteoporosis [29, 30]. However, these previous studies were not conducted in breast cancer survivors who may have higher risk for osteoporosis, in addition to competing demands from multiple illnesses. We also found that many participants (57%) recognized that a lifetime of low calcium/vitamin D intake increases the risk of osteoporosis, but this knowledge did not translate to an association with self-reported adherence to calcium/vitamin D supplements. In addition, participants with poor osteoporosis knowledge may not be aware of the importance of also including calcium rich foods in their diet nor which foods are high in calcium. Health care providers should better educate older breast cancer survivors who are at higher risk of developing osteoporosis about osteoporosis risk factors and preventive behaviors.
Our study participants had a low sense of seriousness and perceived risk of osteoporosis compared to participants of similar age, menopausal status, and bone density in other studies [31, 32]. This is consistent with the low level of osteoporosis knowledge we found among our participants since the majority did not know that menopause is a risk factor for osteoporosis. Participants may also be more likely to believe osteoporosis is not a serious threat and have low perceived risk of developing osteoporosis if they do not have any clinical evidence or symptoms of osteoporosis such as history of fracture or bone pain. In addition, Hsieh et al. [33] showed that compared to breast cancer, cardiovascular disease, and neurological disorders, most women were less concerned with osteoporosis and therefore had lower perceived susceptibility. Given that our population were all breast cancer survivors, they may have perceived osteoporosis to be much less serious or risky. In addition, as more than half our cohort was obese and overall, there were few participants who had a diagnosis of osteopenia, it is possible that they may have felt less susceptible. In fact, we did find that those with lower lumbar bone density scores had higher susceptibility scores. This suggests that knowledge gained from bone density score may increase perceived susceptibility to osteoporosis.
Osteoporosis knowledge and health beliefs were significantly associated with osteoporosis preventive behaviors. In particular, those with higher knowledge and health motivation scores were more likely to engage in strength-training exercises. We also found that marital status was associated with exercise, but only health motivation remained significantly associated with exercise after adjustment for marital status and osteoporosis knowledge. Thus, finding ways to increase health motivation among older breast cancer survivors may help increase their engagement in strength training exercises which can not only decrease their risk for developing osteoporosis but may also improve their breast cancer prognosis.
The results of the current study are limited due to a modest sample size, which did not enable us to detect stronger associations between osteoporosis knowledge, health beliefs and behaviors. Adherence to supplements, exercise, and diet are not specific to osteoporosis and may reflect a general tendency to keep a healthy lifestyle and prevent or treat other conditions. The study is also cross-sectional in design conducted at a single medical institution, thus limiting generalizability. However, our cohort was diverse in terms of race and socioeconomic status making it representative of the community and other large cities in the United States. Finally, the majority of our participants had a prior bone density scan, which may have affected their perceptions and behavior to osteoporosis.
The results of the present study have implications for practice, future research, and policy. First, given the low knowledge and perceived risk among participants, it is possible that they are more concerned with managing their breast cancer and diabetes diagnoses and less concerned about osteoporosis. Future research should explore the interrelationship between breast cancer, diabetes, osteoporosis beliefs, and their impact on behaviors that promote bone health. Second, clinical guidelines for bone health in breast cancer patients on AIs have been issued but compliance within the oncological community is inconsistent. Barriers that prevent translating these guidelines into practice should be identified to reduce future suboptimal or inadequate treatment of bone health. Lastly, participation in strength-training exercises and adherence to dietary calcium intake were low among participants, but greater health motivation was the only factor associated with exercise. This finding supports implementation of osteoporosis preventive programs in breast cancer care directed towards increasing strength-training exercise and calcium intake.