Women with false positive mammography result more likely to have breast cancer in long term: JAMA

Mammography is a popular diagnostic method used to screen breast cancer, mammography screening programs have made a huge difference by reducing breast cancer mortality of more than 20%. However one of the major drawbacks of mammography screening is the occurrence of a false-positive mammography result.

In US, approximately 11% of women receive a false-positive result from a single screening, while in Europe, the corresponding proportion is approximately 2.5%. Along with psychological stress, previous studies consistently show that women with false-positive results have an increased risk of developing breast cancer within 10 years of follow-up compared with women without false-positive results.

A new study in JAMA Oncology reports that women in Sweden with a false-positive mammography result had an elevated incidence of breast cancer and mortality for up to 20 years. The increased breast cancer risk varied according to age, mammographic breast density, and whether a biopsy was performed during recall or not. In addition, the risk of breast cancer was more pronounced during the initial years after the false-positive mammography result.

The researchers conducted a population-based, matched cohort study was conducted in Sweden from January 1, 1991, to March 31, 2020. It included 45 213 women who received a first false-positive mammography result between 1991 and 2017 and 452 130 controls matched on age, calendar year of mammography, and screening history (no previous false-positive result). The study also included 1113 women with a false-positive result and 11 130 matched controls with information on mammographic breast density from the Karolinska Mammography Project for Risk Prediction of Breast Cancer study. Statistical analysis was performed from April 2022 to February 2023.

The key findings of the study are

• A total of 497 343 women (median age, 52 years) were included in the study. The 20-year cumulative incidence of breast cancer was 11.3% among women with a false-positive result vs 7.3% among those without, with an adjusted hazard ratio (HR) of 1.61.

• The corresponding HRs were higher among women aged 60 to 75 years at the examination (HR, 2.02; 95% CI, 1.80-2.26) and those with lower mammographic breast density (HR, 4.65; 95% CI, 2.61-8.29).

• In addition, breast cancer risk was higher for women who underwent a biopsy at the recall (HR, 1.77) than for those without a biopsy (HR, 1.51).

• Cancers after a false-positive result were more likely to be detected on the ipsilateral side of the false-positive result (HR, 1.92) and were more common during the first 4 years of follow-up (HR, 2.57) during the first 2 years (HR, 1.93 at >2 to 4 years).

• No statistical difference was found for different tumor characteristics (except for larger tumor size). Furthermore, associated with the increased risk of breast cancer, women with a false-positive result had an 84% higher rate of breast cancer death than those without (HR, 1.84).

Researchers concluded that “This study suggests that the risk of developing breast cancer after a false-positive mammography result differs by individual characteristics and follow-up. These findings can be used to develop individualized risk-based breast cancer screening after a false-positive result.”

Reference: Mao X, He W, Humphreys K, et al. Breast Cancer Incidence After a False-Positive Mammography Result. JAMA Oncol. Published online November 02, 2023. doi:10.1001/jamaoncol.2023.4519