NEW YORK (Reuters Health) – In a large cohort of women with advanced breast cancer, about 40% of fractures were cancer-related, researchers say.
Breast cancer is associated with an increased fracture risk “attributed in part to estrogen deficiency, aromatase inhibitors, frailty, and skeletal metastases,” Dr. Joan Lo of Kaiser Permanente Northern California in Oakland and colleagues write in JAMA Network Open.
However, Dr. Lo told Reuters Health by email, the team’s previous work “suggested that to accurately assess risk and risk factors for osteoporosis and fractures, we needed to separate fractures which were pathologic — meaning caused by the cancer — and fractures which were not.”
Dr. Lo and colleagues analyzed data from 5,010 women on endocrine therapy in Kaiser Permanente’s Pathways cohort. The women were followed for up to 10 years after an invasive breast cancer diagnosis for incident fracture. The mean age was 60; 91% were stage I/II at initial diagnosis; 73% were non-Hispanic white; 10.8%, Asian; 9.4%, Hispanic, 4.9%, Black; and 1.6%, other or unknown ethnicity.
Three hundred and forty women (6.8%) had incident fracture(s) during follow-up at a median of 6.7 years: 46 hip, 104 vertebral, 78 humerus, and 137 wrist. These excluded prevalent fractures, which accounted for 46 of 150 (30.7%) vertebral fractures.
Among women with hip fracture, 43.5% were age 80 or older, versus less than 25% for women with vertebral (22.1%), humerus (19.2%), or wrist fracture (15.3%).
Roughly 21% of incident vertebral fractures were pathologic, as were 8.7% of incident hip fractures; the latter is consistent with the 10% reported in a 2014 publication.
By contrast, 99.3% of incident wrist fractures were nonpathologic, as 96.2% of humerus fractures.
By tumor stage, 17.2% of vertebral fractures among women with initial stage I/II disease were pathologic, versus 41.2% among women with initial stage III/IV.
Dr. Shipra Gandhi, a medical oncologist at Roswell Park Comprehensive Cancer Center in Buffalo, New York, commented on the study in an email to Reuters Health. “The study has some important implications,” Dr. Ghandi said. “Differentiating between pathologic and non-pathologic fractures is important for management decisions, as pathologic fractures may benefit from radiation treatment. The study highlights that clinicians should have a low threshold to consider incident vertebral fractures as pathologic in nature, especially for patients with higher-risk breast cancer.”
“Future research should focus on including risk factors to develop a prediction model for development of pathologic fractures so that aggressive osteoporotic fracture prevention care – including use of bisphosphonates, radiation therapy, etc. – could be instituted early on,” she said.
“Another question for future exploration,” she added, “is whether use of more frequent serial DEXA scans, especially for stage III or IV patients, help in risk stratifying to identify those who would benefit from aggressive interventions early.”
SOURCE: https://bit.ly/3DVG5tO JAMA Network Open, online November 17, 2021.
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