Researchers from Australia have developed a model that predicts future 10-year risk of breast cancer after a patient has been diagnosed with ER-positive/HER2-negative breast cancer, according to recent research from the 2025 ASCO Annual Meeting. 

For patients considering a bilateral mastectomy, there is a need to balance the personal risk of a future breast cancer diagnosis and the potential downsides associated with a mastectomy, such as morbidity, financial toxicity, and increased use of healthcare system resources. 

The researchers developed a model using data from 1,162 breast cancer cases in Australia from two cohort studies. Patients in the cohorts had been diagnosed with invasive ER-positive/HER2-negative breast cancer. 

In total, there were 187 breast cancer cases over a median 13.8 years of follow-up, which included 88 ipsilateral cases, 96 contralateral cases, and three cases of unknown laterality. Of the cases identified, 161 were considered invasive, while 26 cases were identified as ductal carcinoma in situ. 

The researchers also performed a flexible parametric survival analysis that considered time since diagnosis and any-cause mortality. They used data from 3,136 cases from the international Breast Cancer Association Consortium, which included 181 breast cancer events, to validate the model.  

Researchers also assessed predictors of future risk such as age at diagnosis, number of first-degree relatives with breast cancer, polygenic risk score, use of breast conservation or unilateral mastectomy, and use of chemotherapy or radiation. 

The results showed the model had an area under the curve (AUC) at 10 years of 0.66 and an AUC of 0.65 when polygenic risk score — which is not often available in clinical practice — was not included. 

“This model provides valid estimates of 10-year [breast cancer] risk after a 1st ER+ HER2- [breast cancer] and may be useful in collaborative decision-making between patients and their surgeons when considering bilateral mastectomy,” 

- Kelly-Anne Phillips, MD, medical oncologist at the Peter MacCallum Cancer Centre in Melbourne, and fellow authors wrote. 

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Reference:  
https://meetings.asco.org/abstracts-presentations/251522 

Disclosures: MD /alert could not confirm financial disclosures at the time of reporting. This study was supported by the National Breast Cancer Foundation and National Health and Medical Research Council in Australia. 

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By Jeff Craven