Approximately 33% of older women with early-stage breast cancer are not being tested for bone mineral density (BMD) before starting aromatase inhibitor therapy, according to a new and to date the largest population-based study on this topic (Charlson J, et al. J Natl Compr Canc Netw. 2016;14:875-880).
BMD testing rates decreased from 73% for women aged 67 to 70 years to 51% for those aged ≥85 years. The proportion of women who do not undergo BMD testing or receive bisphosphonates increased with older age as well.
Older age and aromatase inhibitor therapy increase the risk for bone fracture. The American Society of Clinical Oncology and the National Comprehensive Cancer Network guidelines recommend baseline BMD testing before starting aromatase inhibitor therapy.
“This study highlights suboptimal US compliance with guideline recommendations for baseline BMD testing when starting aromatase inhibitor therapy. Older women, at higher risk for fractures in general, are least likely to obtain BMD testing, and the slight increase in empiric treatment for those women did not close the gap,” noted lead investigator John Charlson, MD, Associate Professor of Medicine, Division of Hematology and Oncology, Medical College of Wisconsin, Milwaukee, and colleagues. They called for increased awareness of this knowledge gap to optimize therapy.
“This is the largest and most contemporary population-based study to date assessing the quality of bone health management in postmenopausal women with breast cancer initiating adjuvant AI [aromatase inhibitor] therapy, with BMD testing examined through 2012; the first to both assess screening and empiric treatment [with bisphosphonates]; and the first to include large numbers of older women,” they observed.
The study population included 19,585 Medicare-enrolled women aged ≥67 years who underwent breast cancer surgery in 2006 or 2007 and started aromatase inhibitor therapy within 1 year after surgery.
The unadjusted BMD testing rates were lowest (26%) in the oldest age-group (≥86 years), and the rates of bisphosphonate use without BMD testing were slightly higher (10%) in this age-group. The investigators noted that a strategy of baseline BMD testing, followed by treatment with bisphosphonates for osteoporosis or osteopenia, is considered cost-effective compared with empiric bisphosphonate treatment in all women receiving aromatase inhibitors.
The percentage of women starting adjuvant aromatase inhibitor therapy without evidence of BMD testing or bisphosphonate use increased from 24% in patients aged 67 to 70 years to 40% in patients aged ≥86 years.
An adjusted analysis showed that older age, comorbidity, low income, and race were all associated with an increased likelihood of starting aromatase inhibitor therapy without baseline BMD testing. Although older age and comorbidity are associated with increased risk for bone fractures, a substantial proportion of women in the highest-risk subgroups were among the least likely to receive BMD testing.
“The reason for this deficiency is unknown, but clinicians should be aware of it so that efforts can be focused on maximizing the therapeutic index in adjuvant breast cancer treatment,” concluded Dr Charlson and colleagues.
