49歳以下にはマンモグラフィー検診は推奨しない(3)

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同じ米国予防医学作業部会US Preventative Services Task ForceScreening for Breast Cancerに40-49歳の推奨を変更した理由が記載されています。
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Explanation of Change in Recommendation

The 2002 USPSTF issued a B recommendation for screening mammography for women 40 years or older. However, it went on to say:

The precise age at which the benefits from screening mammography justify the potential harms is a subjective judgment and should take into account patient preferences. Clinicians should inform women about the potential benefits (reduced chance of dying from breast cancer), potential harms (for example, false-positive results, unnecessary biopsies), and limitations of the test that apply to women their age. Clinicians should tell women that the balance of benefits and potential harms of mammography improves with increasing age for women between the ages of 40 and 70 (6).

The updated USPSTF recommendation endorses this approach to deciding when to start screening. However, the current USPSTF is now further informed by a new systematic review (7), which incorporates a new randomized, controlled trial that estimates the "number needed to invite for screening to extend one woman's life" as 1904 for women aged 40 to 49 years and 1339 for women aged 50 to 59 years. Although the relative risk reduction is nearly identical (15% and 14%) for these 2 age groups, the risk for breast cancer increases steeply with age starting at age 40 years. Thus, the absolute risk reduction from screening (as shown by the number needed to invite to screen) is greater for women aged 50 to 59 years than for those aged 40 to 49 years.

The current USPSTF statement is also informed by the Cancer Intervention and Surveillance Modeling Network (CISNET) modeling studies (8) that accompany this recommendation. The Task Force considered both "mortality" and "life-years gained" outcomes. In this case, given that the age groups (40 to 49 years and 50 to 59 years) are adjacent, the Task Force elected to emphasize the mortality outcomes from the modeling studies. Of the 8 screening strategies found most efficient, 6 start at age 50 years rather than age 40 years. The frontier curves for the mortality outcome show only small gains but larger numbers of mammograms required when screening is started at age 40 years versus age 50 years.

In conclusion, the USPSTF reasoned that the additional benefit gained by starting screening at age 40 years rather than at age 50 years is small, and that moderate harms from screening remain at any age. This leads to the C recommendation. The USPSTF notes that a "C" grade is a recommendation against routine screening of women aged 40 to 49 years. The Task Force encourages individualized, informed decision making about when to start mammography screening.
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1人の生命を救うために、40-49歳では1904人、50-59歳では1339人のがん検診が必要とのこと。過剰診断による不利益と効果、どちらを選択するか。難しい問題です。

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