Incident, proliferative benign breast disease tied to greatest breast cancer risk

Women with incident, proliferative benign breast diseases (BBDs) may have an elevated risk of developing breast cancer, according to a retrospective study conducted in Spain.

“Our results show that women with a BBD diagnosed from the second screening onwards [incident BBD] have a significantly higher subsequent risk of breast cancer than those with a BBD diagnosed on their first mammographic screening,” presented study author Dr Marta Román from the Hospital del Mar Medical Research Institute in Barcelona, Spain, at EBCC 2020.

The researchers assessed data of 629,087 women aged 50–69 years who in total underwent 2,327,384 mammographic examinations in 1994–2015 as part of a population-based screening programme. A total of 9,431 cases of breast cancer and 9,184 BBDs were diagnosed during a mean follow up of 7.8 years.

Women with prevalent BBD, identified at the first breast screening (usually at age 50 years), had an elevated risk of developing breast cancer (adjusted hazard ratio [adjHR], 1.87, 95 percent confidence interval [CI], 1.57–2.24) compared with women without BBD. The risk was even higher among women with incident BBDs (detected at subsequent breast screening visits every 2 years after the first screening; adjHR, 2.67, 95 percent CI, 2.24–3.19). [EBCC 2020, abstract 15]

Breast cancer risk was increased threefold in women with proliferative BBD (adjHR, 3.28, 95 percent CI, 2.60–4.15) compared with women with no BBD, and almost twofold among women with non-proliferative BBD (adjHR, 1.95, 95 percent CI, 1.68–2.27).

When looking at the combined effect of screening and BBD type, breast cancer risk was greatest among women with incident, proliferative BBD (adjHR, 3.92, 95 percent CI, 2.80–5.48).

However, the risk was still elevated in women with prevalent, non-proliferative BBD (adjHR, 1.63, 95 percent CI, 1.32–2.02), prevalent, proliferative BBD (adjHR, 2.85, 95 percent CI, 2.06–3.94), and incident, non-proliferative BBD (adjHR, 2.39, 95 percent CI, 1.95–2.93) compared with women without BBD.

“There was no interaction between screening type and BBD type (p=0.83),” the researchers noted.

Using the results to modify screening strategies

“[P]opulation-based breast cancer screening programmes save lives by detecting cancer at an early stage. However, [they] can raise questions about … the best way of treating women with cancer that may never become a problem … [and] also what to do about women with BBD,” said EBCC 2020 co-chair Professor Javier Cortes from the IOB Institute of Oncology, Madrid and Barcelona, Spain, who was not involved in the study.

“[P]atients and clinicians want to be sure that if BBD does develop into cancer, it can be detected quickly. The[se] results … provide us with useful information that can improve the accuracy of breast cancer risk prediction models so that we can tailor surveillance strategies for patients with this disease,” he added.

“Personalized risk-based screening going beyond the current ‘one-size fits all’ recommendation may increase the effectiveness of breast cancer screening. Including information from BBD, in addition to other factors, to develop risk-based screening approaches can help with the prediction of whether a woman would develop breast cancer in a defined period,” contributed Román. However, she acknowledged the unavailability of information on breast cancer risk factors in this study cohort.

“Clinicians involved in the management of women with BBDs could offer targeted surveillance strategies considering, in addition to other factors, if the BBD was found at first or in subsequent screening examinations. Also, this information will be included in an individualized model that can be used to predict an individual woman’s risk of developing breast cancer in 5 or 10 years’ time,” added lead investigator Professor Xavier Castells, also from the Hospital del Mar Medical Research Institute.