How often should breast screening occur, and when should they start? It used to be annually after a woman reached forty years of age. However, because of the risk of false positives, needless biopsies, extra financial costs, and the psychological distress overtreatment causes, the answer now is “It depends”.
Wouldn’t it be better to have a more definitive answer? Oguzhan Alagoz, from the University of Wisconin-Madison created a decision-making model that will do just that. Alagoz says that with the model, he can tailor breast-screening decisions to fit a woman’s calculated risk of invasive breast cancer – instead of just focusing on her age.
His model is described in Operations Research, September/October 2012 issue.
The decision-making model not only has the patient’s genetics, age and other personal risk factors, but also details on her screening history.
Alagoz said:
“We illustrate how this extra piece of information might change which decision is optimal and help doctors make better screening decisions,” Alagoz says. “Unlike other cancers such as colorectal, none of the existing breast cancer population-based guidelines currently consider this.”
Societies and governments departments are unable to agree on when women should start breast screening. Some, such as the American Cancer Society, still stick to 40 years as the best time to start, while the US Preventive Services Task Force changed it to 50 years in 2011. It added that individual doctors and patients should decide on whether to start earlier.
Until a few years ago, routine mammographies were thought to reduce national breast cancer rates by at least 20% to 30%. However, several recent studies have found this is not the case at all. A large Swedish study found that breast screening has limited or no impact on breast cancer mortality among females aged 40 to 69 years. Their study was published in the Journal of the National Cancer Institute, July 17, 2011 issue.
Another study, however, carried out by researchers at the department of public health at the Erasmus MC at Rotterdam in the Netherlands, and published in Cancer Epidemiology, Biomarkers & Prevention found that screening mammograms brought breast cancer mortally rates down by 49%.
For breast screening to be effective and beneficial for society and individual patients, its benefits need to be maximized, while at the same time minimizing its potential harms, which include over- or under-screening.
The model focuses on each patient’s individual cancer risk, which is calculated from a series of factors, including her family history, lifestyle, as well as previous screening history. The woman’s risk of cancer – and risk of “transition” to new states, such as biopsy and treatment – would go down if all her mammograms came back negative. This would mean that in some cases, doctors might not recommend breast cancer screening for an individual patient for several years.
By tailoring screening needs to the individual patient, Alagoz says his model will increase the quality of life and number of years a woman enjoys, while bringing down the total number of mammograms a population as a whole receives, compared to standard population based screening recommendations.
Alagoz said:
“Our model might help reduce the number of unnecessary mammograms, which account for approximately $100 million in overspending per year in the United States.”
Individualizing breast screening recommendations will save many high risk lives and reduce unnecessary biopsies, pointless radiation exposure, over treatments, costs and stress for low risk women.
Alagoz added that his model can create “a single easy statistic to describe multiple risk factors, a point that might ease communication among the radiologist, patient and referring physician, and perhaps even facilitate shared decision-making in a more partnership-oriented patient-clinician relationship.”
The majority of women considerably overestimate their risk of dying from breast cancer, they also overestimate the benefits of screening mammography on reducing that risk. Some experts say that if women fully understood how small, but statistically significant, the impact of mammographies are on overall cancer mortality rates, most of them would refuse them.
Nobody appear to agree on what the contribution of mammographies to the overall health and lifespans of populations are. For women with benign lesions, mammographies can cause emotional distress and financial costs.
The majority of patients accept the false positive risk in breast screening; in fact, most say it is not very distressing. Although many patients find the recall extremely frightening, they are relieved when told it was a false positive (this occurs in about 90% of cases).
Routine breast screening’s major effect is to significantly increase early breast cancer detection rates, particularly for non-invasive ductal carcinoma in situ, which is sometimes called “pre-breast cancer”. This type of cancer very rarely ever forms a lump. Mammographies can detect such breast malignancies very early on; however, most of them never become life-threatening. This leads to the argument that mammographies on a large scale should not claim to save lives, but do cause unnecessary surgery, distress and financial costs for patients.
In October 2011, Scottish researchers reported in Health Technology Assessment that mammographic monitoring should be done once a year in high risk women and once every 3 years for others.
Written by Christian Nordqvist