Endometrial cancer: could bone loss drugs help?

Researchers are suggesting that drugs widely used for the prevention of bone loss could have powerful anticancer properties, with women using bisphosphonates half as likely to develop endometrial cancer as women who do not use the medicine.

A medicine commonly used to treat bone conditions such as osteoporosis may have potent anticancer properties.

Bisphosphonates - medications that slow or stop the natural dissolving of bone tissue - have previously been identified as having the ability to prevent tumor cells from multiplying or invading other healthy tissues.

These drugs are commonly used to treat osteoporosis, a condition whereby bones become weak and brittle as not enough new bone tissue is created to sufficiently replace old, broken down tissue.

According to the researchers, endometrial cancer accounts for almost half of all new gynecological cancers diagnosed in the US. It is also the fourth most common malignancy to be diagnosed in women. In 2014, an estimated 52,630 cases of uterine cancer will have been diagnosed, with around 8,590 women dying from endometrial cancer (98%) and uterine sarcomas (2%).

Bisphosphonates have already been shown by researchers to reduce the risk of other cancers, however, this study is the first to show the risk of endometrial cancer may also be reduced.

For the study, published in CANCER, the team analyzed data from the National Cancer Institute's Prostate, Lung, Colorectal, and Ovarian (PLCO) Screening Trial. This data included questionnaires containing information on bone medication use.

In their analysis, the researchers chose only to investigate bisphosphonates containing nitrogen, as these have been identified as having stronger anticancer activity.

Nitrogen form of bisphosphonates 'may reduce the endometrial cancer risk'

Data for 29,254 women were examined by the team. They took into account factors known to be associated with high or low estrogen exposure such as age, body mass index (BMI) and smoking status.

The hormone estrogen connects both osteoporosis and endometrial cancer. An increase in estrogen levels in the body raises the risk of endometrial cancer, while a fall in estrogen levels is a major risk factor for the development of osteoporosis.

After adjusting for these covariates, the authors found that bisphosphonate users were around half as likely to develop endometrial cancer than those who did not use the medication.

This study suggests that women who need bone strengthening medications and who have increased risk for endometrial cancer may want to choose the nitrogen form of bisphosphonates because this form may reduce the risk of endometrial cancer.

Although the population sample used for the study was diverse and followed for nearly 20 years, nearly all of the endometrial cancer cases studied were of one particular type. As a result, the findings cannot be considered significant for patients with type 2 endometrial cancer.

The authors acknowledge that they were also unable to include an analysis of the duration of exposure to bisphosphonates, which would need to be addressed by further research.

However, additional studies are needed that include other potential confounders and a larger sample so that type 2 endometrial cancer could be assessed more confidently. A randomized trial in postmenopausal women that assessed endometrial, breast and colorectal cancer would be ideal.

Earlier this year, another team of researchers reported on a study finding that the risk of uterine cancer decreases by 81% among patients who undergo bariatric surgery.

References:

1.  Protective effect of bisphosphonates on endometrial cancer incidence in data from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial, Sharon H. Alford, et al., CANCER, doi: 10.1002/cncr.28952, published online 22 December 2014,abstract.
2.  CANCER news release, accessed 19 December 2014 via Wiley.
3.  Additional source: American Cancer Society What are the key statistics about endometrial cancer?, accessed 19 December 2014.
4.  Additional source: Mayo Clinic Osteoporosis - definition, accessed 19 December 2014.
5.  Additional source: WebMD Bisphosphonates for osteoporosis, accessed 19 December 2014.