Osteoporosis therapy is associated with improved survival without an increased risk of visceral metastasis in postmenopausal women receiving adjuvant aromatase inhibitors (AIs) for hormone-receptor-positive breast cancer, according to a new analysis.
"All women with early breast cancer and osteoporosis should receive a bisphosphonate or denosumab,” Dr. Allan Lipton from Penn State Hershey Medical Center, in Hershey, Pennsylvania, told Reuters Health by email. “At present the antitumor effect as shown in AZURE, the meta-analysis, and our trial would favor a bisphosphonate.”
Bisphosphonates are used to treat or prevent bone loss due to AIs and chemotherapy, but they also appear to prevent the recurrence of early breast cancer.
Dr. Lipton and colleagues in the NCIC Clinical Trials Group’s MA.27 study examined whether osteoporosis therapy with bisphosphonates affected outcomes in more than 7,500 postmenopausal breast cancer patients (median age, 64 years) treated with an adjuvant AI (exemestane or anastrozole).
Most (85%) of the nearly 1,300 women reporting osteoporosis said they were taking osteoporosis medication; in addition, 815 women were taking the drugs at baseline, the researchers note in Cancer, online May 2.
Patients receiving osteoporosis therapy had a significantly better event-free survival (EFS) throughout follow-up, compared with women who did not receive osteoporosis therapy.
Five-year EFS among women with osteoporosis was 89% for those with osteoporosis therapy, three percentage points better than those with osteoporosis who did not receive osteoporosis therapy (86%).
Women without osteoporosis also fared better, in terms of five-year EFS, with osteoporosis therapy (92%) than without it (87%).
Osteoporosis treatment begun more than 30 days before relapse was associated with a 33% lower risk of having a cancer-related event, and longer osteoporosis therapy during the trial was associated with better EFS.
Results were similar for distant disease-free survival (DDFS), but osteoporosis therapy was not associated with the incidence of visceral-only metastasis.
“The overall good experience of these patients precluded delineation of specific subgroups who could benefit most from receipt of osteoporosis therapy, but we think it strongly advisable that those with osteoporosis be managed with bisphosphonate therapy,” Dr. Lipton concluded. “The results of adjuvant denosumab in the D-CARE trial are awaited.”
Dr. V. Craig Jordan from the University of Texas MD Anderson Cancer Center in Houston, who was not involved in the study, told Reuters Health by email, "It is clear AIs increase the risk of osteoporosis - bone-building agents must be employed. The bonus is that there is an increase in EFS and DDFS with bisphosphonates.”
“This is a story that started with aspirin in the laboratory with Trevor Powles in his PhD in the 70s,” he said. “He showed metastases were reduced, but it did not translate to the clinic. Herbie Fleich brought bisphosphonates into the frame. The Marsden trial showed decreases in metastases, so the current results build upon and confirm the legacy of the past.”
Dr. Peyman Hadji from Krankenhaus Nordwest in Frankfurt, Germany, who has studied the management of AI-associated bone loss in women like these, said, "If women receive adjuvant bisphosphonates for bone protection, they also have an added benefit with regard to their breast cancer outcome.”
Dr. Hadji, who also was not involved in the new research, led an international expert group that recommended adjuvant bisphosphonate therapy for women receiving adjuvant AI treatment for their breast cancer.
“As osteoporosis is a common side effect of aromatase inhibitors,” he told Reuters Health by email, “bone mineral density testing should be offered to all patients with breast cancer and endocrine treatment.”