Bisphosphonate ‘Drug Holidays’: Are They Beneficial?

Other Benefits of Bisphosphonates

Bisphosphonates are multipurpose drugs. They are used for osteopenia and osteoporosis prevention as well as the management of breast cancer and other cancers that have spread to the bone. However, recent research has also suggested that bisphosphonates may be helpful in the prevention of certain cancers.

According to a new analysis published in December 2014 in Cancer, women who use bisphosphonates may have a lower risk for endometrial cancer.1 In the analysis of 29,254 women, bisphosphonate users were half as likely to develop endometrial cancer. Other studies have also show that bisphosphonates may reduce the risk for certain cancers, but this was the first analysis to demonstrate a reduction in the risk for endometrial cancer with bisphosphonate use, according to the researchers. Further, several studies have suggested that bisphosphonates may help prevent other cancers, including lung, colon and breast cancers.

Additionally, another study presented in June 2014 at the American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago indicated that women with metastatic breast cancer may be able to take zoledronic acid less often after the first year of monthly treatment.2

Specifically, results indicated that receiving zoledronic acid every 12 weeks after 1 year of monthly intravenous administration was as efficacious as continuing to receive monthly treatment, said study investigator Gabriel Hortobagyi, MD, professor of medical oncology at the University of Texas MD Anderson Medical Center in Houston.

Findings from this study could have an impact not just in the setting of metastatic breast cancer but for other solid tumors as well, such as multiple myeloma, where monthly intravenous bisphosphonates are used to prevent skeletal events and the loss of bone mass, according to Dr. Hortobagyi.

“Bisphosphonates stay in your blood for many, many years, and the reality is that bone has a very large capacity for storing bisphosphonates, and we don’t know what the limit is and how much it can accept. If you give lower doses or administer the drug less frequently, you would have fewer serious side effects. But that still has to be demonstrated. The studies are relatively small, and we don’t know if this applies to everybody,” Dr. Hortobagyi said in an interview with Endocrinology Advisor.

At present, there appears to be no “optimal” bisphosphonate treatment regimen because the studies are still being conducted. However, the current body of clinical evidence would suggest that structured holidays may be highly beneficial for a significant number of patients provided the patients are adequately monitored and reevaluated on a regular basis.


  1. Alford SH et al. Cancer. 2014;121(3):441-447.
  2. Hortobagyi GN et al. LBA9500. Presented at: 2014 American Society of Clinical Oncology Annual Meeting; May 30-June 3, 2014; Chicago.