Tumor cells from breast cancer can spread to the
bones resulting in bone resorption. This process releases a number of
bone-derived growth factors that in turn promote survival and growth of cancer
cells. Thus, preventing bone resorption
using drugs from a group called bisphosphonates could help to prevent or delay
the onset of metastasis, and thus improve survival in breast cancer patients
Some previous studies indicate that bisphosphonates reduce the chances of
recurrence and death in patients with breast cancer.
Bisphosphonates are normally used for osteoporosis,
a bone condition that often affects postmenopausal women. Osteoporosis results
in thinning of bones, which makes them vulnerable to fractures. Thus, if bisphosphonates prove to be useful
in breast cancer, they would provide additional benefit in preventing
osteoporosis in these patients.
A study was
carried out to evaluate the benefit of a bisphosphonate named zoledronic acid
in the treatment of breast cancer
. The results of this study were recently published
in the New England Journal of Medicine. 3360 women suffering from stage II or early
stage III breast cancer were included in the study. They all received standard
adjuvant therapy which included radiotherapy and/or chemotherapy as well as
other treatments like trastuzumab, according to the protocol of the institution
in which they were being treated. In addition, one half of the patients
received intravenous zoledronic acid on a periodic basis for a total duration
of 5 years. Surgical treatment was intended after completion of adjuvant
chemotherapy. Patients with distant metastasis or those unable to complete
treatment of the primary cancer were excluded from the study.
researchers found that the number of women who were alive and disease-free at
the end of five years was similar in the two groups
. The number of women who
suffered recurrent cancer or death was also similar in the two groups.
zoledronic acid were prone to dental-related side effects including
osteonecrosis or damage to the jaw
, which is a known side effect of zoledronic acid.
Seventeen cases were confirmed and 9 cases were suspected of zoledronic
acid-induced osteonecrosis. The incidence of fractures, however, was lower in
the group taking zoledronic acid.
deduced that zoledronic acid did not improve survival in these breast cancer
. However, it may show some benefit in women
who have undergone menopause at least 5 years before the start of treatment.
according to the researchers, the use of zoledronic acid to improve survival in
breast cancer patients cannot be recommended
. It may be useful to prevent bone loss due
to cancer treatment in postmenopausal women. The exact effect of zoledronic
acid on various reproductive hormones also needs to be established through
1. Robert E. Coleman et al. Breast-Cancer Adjuvant Therapy with
Zoledronic Acid. N Engl J Med 2011; 365:1396-1405.