Although some defended the January 1997 NIH consensus development panel majority report that did not recommend mammography screening of women ages 40–49 years,50-52
by March 1997, 2 influential organizations, NCI and ACS, had publicly recommended screening women in their 40s. However, inconsistency between these organizations remained with respect to the optimal screening interval for women in that age group. In our study, consistent with new ACS guidelines, there was a decrease in endorsement of biennial screening and an increase in endorsement of annual screening among women in their 40s after public announcements of new screening recommendations. This finding did not differ by race. In addition, there was no significant increase in endorsement of annual screening among women ages ≥50 years. This suggests that the increased endorsement of annual screening in the younger group may be attributed to the guideline changes that were specific to that age group. We were unable, however, to identify factors that might have mediated the relation between changes in screening guidelines and increased endorsement of annual screening among younger women. Additional study is needed to identify such factors and to develop interventions to further impact beliefs about screening frequency.
Nonetheless, the endorsement of more frequent, annual screening mammograms that we observed is consistent with evidence of considerable enthusiasm for cancer screening among persons in the United States.53
For example, following an earlier round of the mammography screening controversy in 1993, when NCI announced that it would no longer support mammography screening of women in their 40s, the vast majority of women in that age group planned to continue with their screening regimens.7,54
In addition, many physicians planned to continue recommending screening to women in their 40s.55,56
This public penchant for screening was reflected in and buttressed by news media, where coverage between 1990 and 1997 largely supported mammography screening.4
Even when reporting on the 1997 NIH consensus development panel’s finding of inadequate evidence for screening younger women, the majority of news stories actually favored screening.57
These findings, which are consistent with our results, suggest that new screening guidelines are more likely to be supported when they call for more frequent screening but not when they recommend less.
Our study has several strengths, including its prospective design, large sample size, broad age range, and ethnic diversity among respondents. In addition, by controlling for multiple potentially confounding variables, we were able to isolate the impact of guideline changes on beliefs about screening frequency and to demonstrate the broad impact of these recommendations across race, socioeconomic status, and other factors. A potential limitation is that our analysis of baseline data was an aggregate-level analysis that compared the group of women interviewed before the guidelines changed with the group interviewed after the guidelines changed with respect to endorsement of annual screening. In such a group-level analysis, it is not possible to determine whether guideline changes influenced beliefs held by individual women. It is, thus, reassuring that results of our individual-level analysis comparing endorsement of annual screening in women at baseline and follow-up were consistent with results of the baseline analysis.
In addition, we could not directly examine whether the increased support of annual screening among women ages 40–49 years that we observed after the guidelines changed was accompanied by an increase in annual screening behavior
among women in that age group. All study participants were due for an annual screening after March 1997, thus precluding comparison of screening behavior before and after the guidelines changed. However, other studies have found a strong relation between behavioral intentions and health behaviors.10
Consistent with those findings, our data showed a significant association between endorsement of annual screening (at baseline) and actual annual screening behavior (at follow-up, postguideline change; P
<.0001). This suggests that the increased endorsement of annual screening that we observed among younger women after the 1997 guideline changes would lead to an increase in annual screening behavior. Nevertheless, post-1997, women in their 40s remained less likely to obtain annual screenings than women in their 50s and 60s.58-60
This is of concern because of mounting evidence that mammography screening has contributed to the decline in breast cancer mortality observed in the United States61,62
and that annual screening, in particular, may detect smaller and more treatable tumors.63,64
A recent study by White and colleagues65
found that a shorter screening interval was associated with less late-stage disease in younger but not older women with breast cancer, so annual screening may be especially important in women ages 40–49 years.
Since the 1997 mammography screening controversy, the public debate about the efficacy of mammography screening and appropriate screening guidelines has continued. In 2001-2002, for example, a contentious debate ensued after publication of a Cochrane review that found that mammography screening did not decrease mortality in either younger or older women.66,67
More recently, in April 2007, reminiscent of the 1997 NIH consensus development panel’s finding of inadequate evidence to recommend screening women in their 40s, the American College of Physicians withdrew its recommendation for regular mammography screening among women in that age group and instead recommended that physicians tailor recommendations based on individual risk of breast cancer, risks and benefits of mammography, and women’s preferences.68,69
Such actions may fuel future controversies over appropriate target populations, screening intervals, and risks and benefits of available screening modalities. Our findings suggest that in the face of new information, patients are likely to endorse recommendations calling for increased mammography screening. However, further study is needed to examine the impact of new recommendations on screening behavior. In addition, acceptance of new technology, such as magnetic resonance imaging (MRI) for breast screening that was recently recommended by ACS,70
has yet to be evaluated. To better inform health policy and respond to individual patients, ongoing assessment of the influence on beliefs and behavior of controversies over mammography screening and of changes in screening guidelines is needed.