Bisphosphonates for treating osteoporosis may significantly reduce risk of breast cancer
Last updated: May 16, 2010
- News type:
- Breast cancer studies
- Conference:
- San Antonio Breast Cancer Symposium, December 2009
- Topic:
- Bisphosphonates may significantly reduce risk of breast cancer
Two new studies presented at the San Antonio Breast Cancer Symposium report that women who use bisphosphonates such as Fosamax, Boniva and Actonel for treating osteoporosis have significantly fewer cases of breast cancer. Participants in the National Institutes of Health-sponsored Women's Health Initiative taking bisphosphonates were found to have almost one third fewer cases of breast cancer (3.3%) compared with the nonusers (4.4%) during an average follow-up period of 7.8 years. The study took into account into account breast cancer- and bone density-related factors such as age, weight, smoking, hormone replacement therapy, and vitamin D use. A second Israeli study of postmenopausal women (both with and without breast cancer) found that those with breast cancer were 29 percent less likely to have been taking bisphosphonates. This study also controlled for breast cancer risk factors such as family history and use of other medications. Neither of the studies was a case-control clinical trial and neither is considered definitive. Bisphosphonates have potential side effects, most seriously jaw bone death. The findings are provocative, but it is still too early to use bisphosphonates to prevent breast cancer, according to one of the lead investigators.
Studies confirm and extend previous findings
Numerous other studies have found that bisphosphonates have chemopreventive properties and can reduce the occurrence and number of bone metastases in women diagnosed with invasive breast cancer. The two new studies extend the chemopreventive findings to women who have not been diagnosed with breast cancer. While bisphosphonates are used in some other countries to prevent recurrence of breast cancer, they are not routinely used for this purpose in the U.S. Nor is it likely that bisphosphonates will start to be used to prevent breast cancer among high-risk women based on these two preliminary studies. Below we summarize some of the important findings to date for bisphosphonates and breast cancer:
- Sequential administration of the chemotherapy agents docetaxel or doxorubicin, followed by the bisphosphonate zoledronic acid, has been found to reduce the growth of bone metastases in animal models of metastatic bone disease in a synergistic manner
- Long-term bisphosphonate use can result in low serum calcium levels. Combined with the finding that increased bone turnover due to calcium deficiency promotes tumor growth in bone, treatment to correct any calcium insufficiency when using bisphosphonates appears warranted
- Bisphosphonates may prevent bone loss caused by breast cancer treatments such as aromatase inhibitors. The benefits of bisphosphonate treatment have been shown to be in addition to those derived from supplementation with calcium and vitamin D
- Risk factors for osteonecrosis of the jaw (which occurs in at approximately 3% of breast cancer patients who take it) include use of dentures and a history of dental extraction. Smoking, periodontitis, and root canal treatment have not been found to increase risk
- In a study of patients with bone metastases, repeated low-dose therapy with zoledronic acid was shown to induce a long-lasting decrease of vascular endothelial growth factor (VEGF) levels, suggesting a mechanism of action by which bisphosphonates may inhibit cancer spread.
At the moment, bisphosphonates are used to treat women with bone metastases, but not patients with early breast cancer. Several adjuvant trials are in progress to evaluate the role of bisphosphonates in women whose cancers have not metastasized.
,
Taxotere,
VEGF,
anthracycline,
aromataseInhibitors,
bisphosphonates,
boneDevelopment,
calcium,
docetaxel,
doxorubicin,
middleEastern,
otherTreatments,
taxanes,
vitaminD
Selected studies
Bisphosphonates may significantly reduce risk of breast cancer
San Antonio Breast Cancer Symposium, December 2009
Two studies presented at the San Antonio Breast Cancer Symposium report that women who use bisphosphonates such as Fosamax, Boniva and Actonel for treating osteoporosis have significantly fewer cases of breast cancer. The 2,816 women in the large National Institutes of Health-sponsored Women΄s Health Initiative taking bisphosphonates (mostly Fosamax) were found to have almost one third fewer cases of breast cancer (3.3%) compared with the 151,952 nonusers (4.4%) during an average follow-up period of 7.8 years. The association persisted after taking into account breast cancer- and bone density-related factors such as age, weight, smoking, hormone replacement therapy, and vitamin D use. However, women taking bisphosphonates were more likely to develop ductal carcinoma in situ (DCIS), a noninvasive form of breast cancer. A second Israeli study had more than 4,500 postmenopausal participants (both with and without breast cancer). Those with breast cancer were 29 percent less likely to have been taking bisphosphonates after controlling for breast cancer risk factors such as family history and use of other medications. Neither of the studies is a case-control clinical trial and neither is considered definitive. Bisphosphonates have side effects, most seriously jaw bone death, which is rare. The fact that bisphosphonates appear to reduce tumor formation in the breast indicate that they may have direct anti-cancer effects in addition to helping bones resist cancer's spread. The findings are provocative, but it is still too early to use bisphosphonates to prevent breast cancer, according to one of the lead investigators.
Adjuvant bisphosphonates in breast cancer: Are we witnessing the emergence of a new therapeutic strategy?
European Journal of Cancer, July 2009
R.E. Coleman The present review was designed to examine the potential for the use of adjuvant bisphosphonates in breast cancer. Although improvements in the treatment of breast cancer have reduced the number of deaths since the late 1980s, metastatic breast cancer still remains the primary cause of cancer death for women in Europe. Therefore, more effective methods to detect and treat micrometastatic disease are urgently needed. Bone is the most frequent site of distant recurrence, accounting for 30 to 40% of all first metastases. Bone tumors are known to release bone cell activating factors. Studies have also reported that the release of bone-derived growth factors and cytokines into the microenvironment can attract cancer cells to the bone surface, as well as promoting their growth and proliferation. Since bisphosphonates are potent inhibitors of bone osteolysis, they are in a position to interrupt this process, thereby inhibiting both the development of bone metastases and the survival of dormant cells in the marrow (which otherwise may be capable of subsequent dissemination to non-bone sites). Furthermore, newer, more powerful amino-bisphosphonates appear to have direct effects on cancer cells, especially when given in combination with chemotherapy. Clinical trials using the early oral bisphosphonate and clodronate were inconclusive. However, recent studies using zoledronic acid indicate that such bone-related treatments might be effective in altering the course of the disease. The authors conclude that results of ongoing large metastasis prevention trials are needed before routine use of adjuvant bisphosphonates can be recommended.
<< Previous
Top
Next >>
