Breast Cancer Overdiagnosis
Definition of Overdiagnosis
Source: National Cancer Institute
Finding cases of cancer with a screening test (such as a mammogram or PSA test) that will never cause any symptoms. These cancers may just stop growing or go away on their own. Some of the harms caused by overdiagnosis are anxiety and having treatments that are not needed.
Some cancers that are diagnosed early do not develop symptoms requiring treatment, while others grow so slowly that the patient outlives the cancer and dies of other causes. Many of these are treated unnecessarily, leading to:
- Unnecessary tests and treatment
- Exposure to dangerous side-effects
- Radiation-induced cancers
- Mental and physical pain
- Infertility
- Inflated survival rates
The rates of breast cancer overdiagnosis
The authors of this study which looked at cancer overdiagnosis stated: We estimate the magnitude of overdiagnosis from randomized trials: about 25% of mammographically detected breast cancers…
This Article, published in the New England Journal of Medicine, found: 31% of all breast cancers are over-diagnosed.
This 2016 review concluded:
· At least 20% of Breast Cancer patients, if left untreated would be alive after 5 years
· limited evidence suggests that around 10% of screen detected Breast Cancers may regress.
Breast cancer overdiagnosis and treatment
This study sheds light on the need for new measures to avoid overdiagnosis and unnecessary treatment.
The study authors say:
A vast range of disorders—from indolent to fast-growing lesions—are labelled as cancer. Therefore, we believe that several changes should be made to the approach to cancer screening and care, such as use of new terminology for indolent and precancerous disorders. We propose the term indolent lesion of epithelial origin, or IDLE, for those lesions (currently labelled as cancers) and their precursors that are unlikely to cause harm if they are left untreated.
The National Cancer Institute’s Breast Cancer Screening (PDQ®)–Health Professional Version (updated June 1, 2018) includes the following :
Theoretically, in a given population, the detection of more breast cancers at an early stage would result in a subsequent reduction in the incidence of advanced-stage cancers. This has not occurred in any of the populations studied to date. Thus, the detection of more early stage cancers likely represents overdiagnosis. A population-based study in the Netherlands showed that about one-half of all screen-detected breast cancers, including DCIS, would represent overdiagnosis and is consistent with other studies, which showed substantial rates of overdiagnosis associated with screening.
The National Cancer Institute’s Breast Cancer Screening (PDQ®)–Health Professional Version (updated June 1, 2018) includes the following :
Theoretically, in a given population, the detection of more breast cancers at an early stage would result in a subsequent reduction in the incidence of advanced-stage cancers. This has not occurred in any of the populations studied to date. Thus, the detection of more early stage cancers likely represents overdiagnosis. A population-based study in the Netherlands showed that about one-half of all screen-detected breast cancers, including DCIS, would represent overdiagnosis and is consistent with other studies, which showed substantial rates of overdiagnosis associated with screening.
Ductal carcinoma in situ
Ductal carcinoma in situ is a pathological entity that is an unintended result of breast cancer screening, rarely diagnosed before screening was adopted. Diagnosis of ductal carcinoma in situ results in immediate treatment with aggressive locoregional therapy; however, the natural history of untreated ductal carcinoma in situ has never been elucidated. Results of studies suggest that only a subset of ductal carcinoma in situ progresses to clinically significant invasive cancer during a patient’s lifetime. The result of this historically aggressive treatment approach is that nearly 50 000 women per year in the USA are diagnosed and given treatment, 20 000 of whom undergo mastectomy, with a growing proportion opting for bilateral mastectomy.
[These women then attribute screening and treatment to saving their lives when in fact they did not need any treatment at all.]
See more at Mammography’s big failing: Overdiagnosis
Updated 2024