American Cancer Society’s New “Average Risk” Mammography Recommendations — Come Closer to the USPSTF’s Controversial 2009 Recommendation — but Disagreement Persists

21 October 2015

Citations

Kevin C. Oeffinger, Elizabeth T. H. Fontham, Ruth Etzioni, Abbe Herzig, James S. Michaelson, Ya-Chen Tina Shih, Louise C. Walter, Timothy R. Church, Christopher R. Flowers, Samuel J. LaMonte, Andrew M. D. Wolf, Carol DeSantis, Joannie Lortet-Tieulent, Kimberly Andrews, Deana Manassaram-Baptiste, Debbie Saslow, Robert A. Smith, Otis W. Brawley, and Richard Wender, Breast Cancer Screening for Women at Average Risk: 2015 Guideline Update From the American Cancer Society, Journal of the American Medical Association [JAMA] 314(15): 1599-1614, DOI: 10.1001/jama.2015.12783 (20 October 2015)

Nancy L. Keating and Lydia E. Pace, New Guidelines for Breast Cancer Screening in US Women, Journal of the American Medical Association [JAMA] 314(15): 1569-1571, DOI: 10.1001/jama.2015.13086 (20 October 2015)

The gist of the 2015 American Cancer Society mammography screening recommendation

From the paper’s abstract:

The ACS recommends that women with an average risk of breast cancer should undergo regular screening mammography starting at age 45 years (strong recommendation).

Women aged 45 to 54 years should be screened annually (qualified recommendation).

Women 55 years and older should transition to biennial screening or have the opportunity to continue screening annually (qualified recommendation).

Women should have the opportunity to begin annual screening between the ages of 40 and 44 years (qualified recommendation).

Women should continue screening mammography as long as their overall health is good and they have a life expectancy of 10 years or longer (qualified recommendation).

The ACS does not recommend clinical breast examination for breast cancer screening among average-risk women at any age (qualified recommendation).

© 2015 Kevin C. Oeffinger, Elizabeth T. H. Fontham, Ruth Etzioni, Abbe Herzig, James S. Michaelson, Ya-Chen Tina Shih, Louise C. Walter, Timothy R. Church, Christopher R. Flowers, Samuel J. LaMonte, Andrew M. D. Wolf, Carol DeSantis, Joannie Lortet-Tieulent, Kimberly Andrews, Deana Manassaram-Baptiste, Debbie Saslow, Robert A. Smith, Otis W. Brawley, and Richard Wender, Breast Cancer Screening for Women at Average Risk: 2015 Guideline Update From the American Cancer Society, Journal of the American Medical Association [JAMA] 314(15): 1599-1614, DOI: 10.1001/jama.2015.12783 (20 October 2015) (at Abstract) (paragraph split)

What is different

From the JAMA editorial:

Several aspects of this new guideline will be particularly striking to patients, clinicians, and others involved in health care:

(1) the more conservative starting age for mammography (45 vs 40 years), which brings the ACS recommendations closer to the US Preventive Services Task Force (USPSTF) guidelines (both the 20094 guideline and the April 2015 draft recommendation statement), which endorse biennial screening for women aged 50 to 74 years;

(2) the proposal for more frequent—annual—screening intervals among women aged 45 to 54 years;

(3) the recommendation against routine screening CBE [clinical breast exam], a marked deviation from prior ACS guidelines and a stronger statement than that of the USPSTF, which in 2009 concluded that the evidence was insufficient to recommend for or against CBE;

and

(4) the recommendation to stop screening among women with a life expectancy of less than 10 years (the USPSTF concluded that evidence is insufficient to assess benefits and harms in women aged ≥75 years).

© 2015 Nancy L. Keating and Lydia E. Pace, New Guidelines for Breast Cancer Screening in US Women, Journal of the American Medical Association [JAMA] 314(15): 1569-1571, DOI: 10.1001/jama.2015.13086 (20 October 2015) (at 3^rd paragraph) (reformatted)

Why the differences?

The authors of the JAMA editorial point to three main methodological differences between the American Cancer Society team’s approach and those the USPSTF used in 2009:

(1) More emphasis on recent observational studies which find a noticeably greater benefit to mammography than clinical trials do

(2) The use of 5-year age groups, rather than 10 — which presumably focuses in better on the transitions in risk at different ages, especially from age 45 to 49

(3) More weight placed upon the larger size of tumors characteristically found in biennial screening, as opposed to annual screening

Do these methodological differences make scientific sense?

Probably not enough to matter, one way or the other, at this (still low) point in our knowledge.

Admittedly, anybody who says an observational study is better than a properly set up clinical trial is an idiot. The only reason one can defend the use of observational study evidence is because so many clinical trials are either methodologically questionable (for screening efficacy purposes) or statistically unpersuasive, due to small sample sizes or inadequate attention paid to population subsets. Both of these qualifications are true for breast cancer.

Second, the American Cancer Society’s emphasis on 45-49 year olds makes arguable physiological sense, due to waning hormone levels as women approach menopause:

[T]he ratio of benefits to harms associated with screening 45- to 49-year-old women could be regarded as closer to the ratio among 50- to 54-year-old women.

On the other hand, the Society’s focus on increased tumor size in biennial screening is questionable:

Although smaller tumors confer better prognosis than larger tumors, the updated . . . analysis does not provide definitive evidence that annual vs biennial mammography for premenopausal women decreases breast cancer mortality.

Thus, despite some face validity in the idea that younger women, who often have more aggressive cancers, might benefit from shorter screening intervals, the actual clinical effects and importance remain uncertain, particularly given the relatively small absolute benefit of screening mammography among younger women, who are less likely than older women to develop or die from breast cancer.

Furthermore, as Oeffinger et al describe, annual mammography confers additional harms compared with biennial mammography, including more false-positive results and unnecessary biopsies.

In other words, just because your tumor is larger when discovered does not mean — all things otherwise equal — that (insofar as we know today) you are more likely to die from it.

Ambiguity bites, doesn’t it?

So what does this mean?

The JAMA editorial points out that it is arguably good that the American Cancer Society recommendations are closer to those the USPSTF came up with in 2009. It’s always nice when the alleged “experts” agree (somewhat).

That said, the recommendations still clash with respect to 45-49 and 50-54 year old women:

The more challenging decisions are for women aged 45 to 54 years, for whom ACS recommends annual screening, but for whom the USPSTF recommends no routine screening (age 45-49 years) or biennial screening (age 50-54 years).

Despite the vast literature on screening mammography, the evidence needed to help women make decisions remains incomplete. Better evidence about the extent of overdiagnosis is especially crucial, as is more information about the preferences and decision processes of diverse populations.

I have written about the basic elements of the mammography screening conundrum, here. The gist was that most women and their medical providers will elect to “mammographize” rather than not. We tend to be more fearful of cancer than of the down-the-road harms that may come from looking for it.

The moral? — When scientific evidence is lacking, our fears and the profit motive guide our behavior

When in doubt, most people (I think) will opt for the mammogram.

PeteFree.com

American Cancer Society’s New “Average Risk” Mammography Recommendations — Come Closer to the USPSTF’s Controversial 2009 Recommendation — but Disagreement Persists