Summary by Cécile Bour, MD
January 12, 2020
Causes of Death After Breast Cancer Diagnosis: A US Population-Based Analysis
The longer women are followed up after being diagnosed with breast cancer, the more likely it is that a cause of death unrelated to the original cancer would be found. The most common cause of death is heart disease, according to the authors of the study published at the end of 2019 in the journal "Cancer".
The study is based on a population of more than 750,000 American women diagnosed with breast cancer over the past 15 years since the beginning of the century.
The proportion of deaths from non-cancerous causes increased from about 28% in the first year after diagnosis to just over 60% among women who lived for more than 10 years after their breast cancer diagnosis.
These women, having survived their cancer longer, had a significantly increased risk of heart disease and Alzheimer's disease compared to general population.
Results according to monitoring
- For deaths within 1 to 5 years after diagnosis, breast cancer itself is the responsible cause in the most frequent cases.
- Among women who died 5-10 years after diagnosis of breast cancer, breast cancer was the cause of death in 38.2%, followed by other cancers in 13.4%, and non-cancerous causes in 48.4%. Heart disease was the most common non-cancer cause of death (15.7%), followed by cerebrovascular disease (stroke) and chronic obstructive pulmonary disease (3.9%) and Alzheimer's disease (3.4%).
- In a more distant follow-up, the cardiovascular cause prevails.
As discussed above, deaths from heart disease and stroke are leading causes of death unrelated to cancer during the post-diagnosis follow-up periods.
But other important causes of death unrelated to breast cancer include chronic liver disease, sepsis, infectious and parasitic diseases. Suicide must also be considered, as it is a significantly higher cause of death than in the general population in all women but particularly among young women.
The high rates of death from heart disease are probably related to the toxicity of chemotherapy (especially anthracyclines) and radiation therapy (especially left breast).
According to Dr. Sonbol, co-author of the article,
1°Some women could be cured of breast cancer and then die of other intervening causes.
2°For other women breast cancer, e.g. metastatic cancer, may have been transformed into a chronic disease, it may be under control through systematic therapy, and then other causes contribute to death.
According to the authors, these findings provide considerable insight into how patients treated for their breast cancer should receive warnings about future health risks.
Hospital physicians who follow up women that have had breast cancer must work closely with general practitioners to ensure optimal long-term follow-up and prevent various pathologies that may occur during the lifetime of these patients after their treatment.
We would add that overdiagnosis, in this context, must become a major concern, all the more so since it throws healthy women into an illness they should not have known about, and exposes them to these other, potentially serious pathologies which are also likely to seriously impact their lives and lead to death.