Do Surgeons Overdiagnose Breast Cancer? I’d like your thoughts
For this post I’ve taken some what I consider to be highlights from NHS Choices and a US Cancer website www.cancer.gov I quote the exact link below. I couldn’t find anything on the web, well not immediately that was form the UK that was not NHS Choices or the newspapers NHS Choices quotes (quite fairly I think).
I’d actually like to start some kind of discussion on overdiagnosis and what it can potentially mean if we are not diagnosed, having met people whose bodies on their death for some other reason are subjected to autopsy and the discovery is then made that the person had had cancer for a long time and hey ho they had been living a good life.
All of this stuff is of course relative.
From NHS Choices
Overdiagnosis occurs where a woman is diagnosed and treated with no survival benefit even though the diagnosis is correct. This can be because the tumour identified would not have progressed to a clinical stage (i.e. it would never have caused symptoms) or because the woman would have died from other causes before the cancer reached a clinical stage.
The researchers included 39,888 patients with invasive breast cancer diagnosed over twenty years, between 1986 and 2005.
The authors estimated the rate of overdiagnosis due to mammography screening as 15–25%. They calculated that for every 2,500 women invited for screening, 6 to 10 women are overdiagnosed, 20 women are diagnosed with breast cancer that is not overdiagnosed, and 1 death from breast cancer is prevented.
This study has some limitations. It was based on data taken from registries rather than gathered to specifically assess screening. Also, the researchers could not adjust for all factors that could have influenced the results, some of which might have offered alternative explanations for the results. In addition, another type of breast cancer called ductal carcinoma in situ was not studied.
However, despite its limitations, the study’s findings are similar to those in other recent publications, including some that have prompted a UK review of breast cancer screening and the type of information offered to women. This review is currently being conducted, although its expected completion date has not yet been announced.
Kalager M, Adami HO, Bretthauer M, et al. Overdiagnosis of Invasive Breast Cancer Due to Mammography Screening: Results From the Norwegian Screening Program. Annals of Internal Medicine. 2012;156:491-499
Evaluation of Breast Symptoms
Breast symptoms may suggest a diagnosis of breast cancer. During a 10-year period, 16% of 2,400 women aged 40 to 69 years sought medical attention for breast symptoms at their health maintenance organization. Women younger than 50 years were twice as likely to seek evaluation. Additional examinations were performed in 66% of patients, with 27% undergoing invasive procedures. Cancer was diagnosed in 6.2% of patients with breast symptoms, most being stage II or III. Of the breast symptoms prompting medical attention, a mass was most likely to lead to a cancer diagnosis (10.7%) and pain was least likely (1.8%) to do so.
Barton MB, Elmore JG, Fletcher SW: Breast symptoms among women enrolled in a health maintenance organization: frequency, evaluation, and outcome. Ann Intern Med 130 (8): 651-7, 1999. [PUBMED Abstract]
Ductal Carcinoma In Situ
Ductal carcinoma in situ (DCIS) is a noninvasive condition that can progress to invasive cancer, with variable frequency and time course. While some authors include DCIS with invasive breast cancer statistics, it has been suggested that the term DCIS be replaced by a classification system of ductal intraepithelial neoplasia, similar to those used to grade cervical and prostate precursor lesions. DCIS is usually diagnosed by mammography, so it is rare in unscreened women. In the United States in 1983, the prescreening era, 4,900 women were diagnosed with DCIS, compared with approximately 63,300 women who will be diagnosed in 2012.