Decision-Making Model Argues Whether Mammography Is Needed

How frequently should breast screening occur, and when it should begin are the topics of a new decision-making model strategy. The current guidelines recommended yearly screening after a woman reached 40 years of age. However, because of the risk of false-positive results, needless biopsies, extra financial costs, and the psychologic anguish caused over treatment, the answer now is “it depends.”

Dr. Oguzhan Alagoz, from the University of Wisconsin-Madison (WI, USA), created a decision-making model that to provide a more definitive answer. According to Dr. Alagoz, he can personalize breast-screening decisions to fit a woman’s calculated risk of invasive breast cancer--instead of just focusing on her age.

The model was described in the September/October 2012 issue of the journal Operations Research issue. The decision-making model not only has the patient’s genetics, age, and other personal risk factors, but also detailed on her screening history. Dr. Alagoz said, “We illustrate how this extra piece of information might change which decision is optimal and help doctors make better screening decisions. Unlike other cancers such as colorectal, none of the existing breast cancer population-based guidelines currently consider this.”

Governments and societies are unable to agree on when women should start breast screening. Some, such as the American Cancer Society, still adhere to 40 years as the best time to start, whereas the US Preventive Services Task Force changed it to 50 years in 2011. It added that individual physicians and patients should decide on whether to start earlier.

Up until several years ago, routine mammography scanning was thought to reduce US breast cancer rates by at least 20%-30%. However, several studies have found this is not accurate. A large Swedish study demonstrated that breast screening has limited or no impact on breast cancer mortality among females aged 40 to 69 years. Their study was published July 17, 2011, in the Journal of the National Cancer Institute. However, another study, performed by researchers from the department of public health at the Erasmus MC (Rotterdam, The Netherlands), and published in Cancer Epidemiology, Biomarkers & Prevention, discovered 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 underscreening. Dr. Alagoz’s decision-making model depends on sequential decision-making techniques, which account for decisions that are taken several times and have a cascading effect, such as an abnormal screening findings that persuades a patient to go for another screening six months later, or a set of risk factors that prompt her to begin screening earlier and more frequently.

The model focuses on each patient’s individual cancer risk, which is calculated from a range 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, clinicians might not recommend breast cancer screening for an individual patient for several years.

By tailoring screening needs to the individual patient, according to Dr. Alagoz, 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. Dr. Alagoz said, “Our model might help reduce the number of unnecessary mammograms, which account for approximately USD 100 million in overspending per year in the United States.”

Personalizing breast screening recommendations will save many high-risk lives and reduce unnecessary biopsies, unnecessary radiation exposure, overtreatments, stress, and expenses for low risk women. Dr. 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.”

What are the ups and downs of breast screening? Most women noticeably overestimate their risk of dying from breast cancer, they also overestimate the advantages of screening mammography on reducing that risk. Some specialists noted that if women completely understood how small, but statistically significant, the impact of mammography screening are on overall cancer mortality rates, most of them would refuse them, according to Dr. Alagoz. No one seems to agree on what are the contribution of mammography to the general health and population lifespan. For women with benign lesions, mammography can cause emotional anguish and financial costs.

The majority of patients accept the false-positive risk in breast screening; in fact, most say it is not very stressful. 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 noninvasive ductal carcinoma in situ, which is sometimes called pre-breast cancer. This type of cancer very rarely ever develops into a lump. Mammography scans can detect such breast tumors very early on; however, most of them never become life threatening. This leads to the case that mammography on a large scale should not profess to save lives, but do cause unnecessary surgery, worry, and financial costs for patients.

Related Links:
University of Wisconsin-Madison
Erasmus MC