Breast cancer mortality has significantly declined in the United States, and this phenomenon is attributed to the combined effect of improved screening and treatments, particularly for hormone receptor-positive cancers.
Between 1975 and 2019, breast cancer mortality in the United States decreased significantly. Therapeutic advances played a pivotal role in this decline, with as many as 30 new anticancer drugs approved between 2010 and 2020. The Cancer Intervention and Surveillance Modeling Network (CISNET) developed simulation models to quantify the relative associations between breast cancer screening, treatment for stages I-III, and treatment for metastatic cancer, and the improvement in breast cancer mortality.
CISNET employed various models to analyze overall mortality trends and trends related to estrogen receptor (ER) and ERBB2 (HER2) status among women aged 30-79 years between 1975 and 2019. In addition, recurrence rates of metastatic forms and their survival were examined, drawing data from the National Comprehensive Cancer Network Outcomes database, which encompasses 82,252 patients with breast cancer, including 7740 with metastatic recurrence.
Significant Mortality Reduction
The study compared women with malignant breast tumors to those without these tumors. The following scenarios were examined: No diagnostic or therapeutic intervention, only screening, treatment for stages I-III, screening and treatment for metastatic forms, and the combined effect of all three interventions.
In 1975, the breast cancer mortality rate in the United States reached 48 per 100,000 women; by 2019, it had dropped to 27 per 100,000. CISNET's various models highlighted an overall absolute reduction in mortality of 58% (ranging from 55% to 61%, based on the model) due to screening and various treatments. This age-adjusted mortality reduction varied according to ER/ERBB2 status, with a notably more pronounced benefit in ER+/ERBB2+ forms: around 71% (68%-76%), compared with ER-/ERBB2- forms, which saw a 39% (35%-42%) reduction.
Screening and Treatments
Analyzing the overall mortality decline revealed that 29% (19%-32%) of it was attributed to treating metastatic forms, 47% (35%-60%) to recent treatments for stages I-III, and 25% (21%-37%) to mammography screening.
Simulations demonstrated that the maximum survival extension for metastatic forms between 2000 and 2019 ranged from 1.9 years (1.0-2.7 years) to 3.2 years (2.0-4.9 years). Survival gains were more significant in ER+/ERBB2+ forms: approximately 2.5 years (2.0-3.4 years) compared with a much lower gain of 0.5 years (0.3-0.8 years) in ER-/ERBB2- forms.
In summary, CISNET's simulation models confirm improvements in breast cancer screening and treatment for stages I-III between 1975 and 2019 in the United States, aligning with a reduction in mortality. They also reveal a lower mortality rate for metastatic forms that is associated with improved therapeutic management. Approximately 25% of the observed decline can be attributed to the treatment of metastatic forms, another 25% to screening, and around 50% to therapeutic advances in early-stage forms (stages I-III).
It's crucial to note that survival gains were more significant in ER+/ERBB2+ forms (about 2.5 years), compared with a mere 0.5 years in ER-/ERBB2- forms, which showcases the effectiveness of treatments for hormone receptor-positive breast cancers.
This work comes with some caveats, however. The accuracy of simulations depends on the precision of baseline data. The models did not consider potential disparities related to age, gender, ethnic origin, or the variable effectiveness of screening and treatments in different regions, which could affect mortality results. In addition, the cost of various interventions was not addressed.
In conclusion, according to various CISNET simulation models, breast cancer screening and treatment were associated with a 58% reduction in mortality, based on data collected between 1975 and 2019. Within this substantial reduction, therapeutic advances in stages I-III contributed 47%, treatments for metastatic forms contributed 29%, and screening contributed 25%.
This article was translated from JIM, which is part of the Medscape professional network, using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.