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Breast density helps predict cancer-related lymphedema risk

JAMA Network Open
Reuters Health - 18/11/2020 - In patients with breast cancer who undergo axillary lymph node dissection, mammographic breast density is among factors associated with the risk of lymphedema, according to new research.

"Currently, about a third of patients are diagnosed in the late stages of lymphedema with few effective treatment options available," Dr. Fei-Fei Liu of Princess Margaret Cancer Centre, in Toronto, Canada, told Reuters Health by email. "We developed a mathematical model to predict lymphedema morbidity. Patients with low breast density were at a higher risk of developing severe lymphedema."

In a paper in JAMA Network Open, Dr. Liu and colleagues note that lymphedema is a surgical complication in about 20% of breast-cancer patients who undergo an axillary lymph node dissection. This risk nearly doubles in surgical treatment combined with radiotherapy or chemotherapy.

Moreover, the condition becomes increasingly challenging to treat over time because of progressive fibrosis.

"Most lymphedema risk models are based on cancer and treatment risk factors, yet these features do not fully account for the risk," Dr. Liu and her colleagues write.

To investigate further, the researchers examined data on 373 women with a mean age of 52.3 years. All had completed curative treatment for a first diagnosis of breast cancer. They were divided into a training cohort of 247 and a validation cohort of 126.

Multivariate linear regression showed that age, BMI and mammographic breast density were among independent prognostic factors associated with lymphedema. This was also the case for the number of pathological lymph nodes and axillary lymph node dissection.

In validation testing there was a moderate but statistically significant correlation between measured and predicted volume of lymphedema. The area under the curve was 0.72 for predicting mild lymphedema and 0.83 for severe lymphedema.

"The study results revealed that fatty breasts cooccurred with worse lymphedema, and on multivariate analysis, breast density added an independent prognostic value beyond BMI," the team sums up.

Dr. Liu added, "Pinpointing who is at greater risk with this model could help high-risk patients and identify and treat lymphedema earlier, when present treatments are most effective."

Dr. Maggie Lee DiNome of the University of California, Los Angeles, author of an accompanying editorial, told Reuters Health by email, "The most important observation from this study is that mammographic breast density, which is a uniformly reported and easily evaluable measure on every mammogram report may be a useful predictor of lymphedema risk for patients undergoing breast-cancer treatment."

"Until we are able to prevent this potentially disabling side effect altogether," she concluded, "we need to be able to counsel patients more accurately about the risks."

By David Douglas

SOURCE: https://bit.ly/3nwF2YW and https://bit.ly/36E7D7z JAMA Network Open, online November 11, 2020.

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