My counseling approach on screening
Notably, the Women’s Preventive Services Initiative recommends that average risk women initiate mammography screening no earlier than age 40 and no later than age 50.6 This creates more flexibility around starting time for screening. In the population of women that I personally counsel, we discuss that fewer women (1 in 68) will experience breast cancer in their 40s compared with in their 50s (1 in 43); therefore as a population, more women will benefit from screening mammography in their 50s. However, there is clear evidence of mortality benefit for a woman in either decade should she develop breast cancer.
We also discuss that the frequency of harms is fairly comparable in either decade, but women who choose to start screening at age 50 will obviously not experience any callbacks or screening-associated benign breast biopsies in their 40s. With this understanding of benefits and harms, most (but not all) average risk women in my practice choose to start screening at age 40.
Related articles:
Breast cancer screening: My practices and response to the USPSTF guidelines
Be mindful of study limitations
The study by Arleo and colleagues has several weaknesses.5
Simulation studies/computer models have limitations. They are only as accurate as the assumptions that are used in the model. However, CISNET modeling has the benefit of having 6 different models with different assumptions on mortality, efficacy of mammography, and efficacy of treatment, and Arleo and colleagues’ analysis takes the mean of these 6 different models.5 It is reassuring to know that the modeling results are consistent with virtually all studies that show that annual screening mammography has a mortality benefit for women in their 40s.
Cost differences are not included. The actual cost of differences between the strategies is difficult to calculate and was not analyzed in this study. While it is easy to calculate the “front end” costs in a study like this (for example, how many more mammograms or biopsies in the different strategies), it is very difficult to calculate the “back end” costs (such as avoided chemotherapy or end-of-life care).
Overtreatment and overdiagnosis have been discussed extensively with regard to the different screening strategies. For example, approximately 80% of women with ductal carcinoma in situ (DCIS) have these tumors detected on screening mammography, and DCIS is not an obligate precursor to invasive breast cancer. Because the natural history of DCIS cannot be predicted, treatment is recommended for all women with DCIS, even though many of these tumors will remain indolent and never cause harm. As a result, concerns have been raised that more intensive screening strategies may result in more overdiagnosis and overtreatment compared with less intensive strategies.
Increasingly, this argument has been questioned, since the prevailing thought is that DCIS does not regress or disappear on mammography. In other words, if DCIS is present at age 40, it will be detected whenever screening starts (age 40, 45, or 50), and age of starting screening or the screening interval will not impact overdiagnosis or overtreatment.7
Related articles:
More than one-third of tumors found on breast cancer screening represent overdiagnosis
Counsel patients, offer screening at age 40
While 3 different breast cancer mammography screening strategies are recommended in the United States, the study by Arleo and colleagues suggests that based on CISNET data, the A40–84 strategy appears to be the most effective at reducing breast cancer mortality and resulting in the most life-years gained. This strategy also requires the most lifetime mammograms and results in the most callbacks and benign biopsies. Women should be offered annual screening mammography starting at age 40 and should start no later than age 50 after receiving counseling about benefits and harms.
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