Can a chest CT evaluate osteoporosis and fracture risk in patients with breast cancer?

This study was carried to examine the effectiveness of using chest computed tomography (CT) for the screening of osteoporosis (OP) and predicting the risk of fractures (bone breaks) in patients with breast cancer (BC). The authors found that CT can be used for predicting OP and determining the risk of fractures in these patients. 

BC is the most common form of cancer found in women. OP is a disease of the bone density decreases. Therefore, the bones become brittle and patients with OP have a high risk of developing fractures at minor trauma such as falling from a standing posistion. OP happens in most women after menopause. However, patients with BC have an increased risk of OP due to BC treatments.

Guidelines in the United States recommend that women with BC who are at high risk of developing OP undergo bone-mineral density (BMD) assessment and monitoring. Currently, dual-energy X-ray absorptiometry (DXA) is the standard for BMD assessment due to its low-cost, low radiation exposure, and its ability to monitor treatment response. Having a DXA T-score of -2.5 usually indicates that a patient has OP. Technician training and the presence of fractures can result in varying results. 

CT is an imaging technique widely used to assess BC spread. Assessment of the vertebrae (bones of the spine) can be used as an indicator of OP. There have been no studies until now that have compared the use of CT in diagnosing OP in patients and comparing them to DXA scanning. 

There were 414 women with BC included in this study. All patients underwent chest both CT and DXA examinations 2 times each within 1 year. The authors compared how well the x-rays penetrate the bone of the L1 vertebra on CT (L1 vertebral attenuation) to the DXA T-score.

21.3% of the patients experienced fractures during this study. Survival without fracture was measured at a threshold of 90 HU. HUs (Hounsfield units) are the measure of radiodensity on CT scans. Fracture-free survival was lower in patients with an attenuation level of 90 HU or lower on CT, as well as with DXA T scores of -2.5 or lower. L1-vertebral attenuation levels on CT were correlated with DXA T scores.

The authors concluded that L1 attenuation of 90 HU or lower relates to lower bone density and can be used to assess the risk of OP and fracture in patients with BC. 

This study was carried out in one Asian institution which may not be translatable to the worldwide population. Also, the study was based on medical records and information may have been missing. Further studies are needed.