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J-START follow-up: adjunctive ultrasound reduced advanced breast cancer incidence, not mortality

In the trial's target population, Asian women aged 40 to 49 years with dense breast tissue, adding ultrasonography to mammography reduced advanced breast cancer incidence for up to 8 years; whether this lowers mortality remains unconfirmed.

  • Narumi Harada-Shoji, MD PhD; Akihiko Suzuki, MD PhD; Takanori Ishida, MD PhD; Seiichiro Yamamoto, PhD; Seiki Kanemura, MD PhD; Takuhiro Yamaguchi, PhD; et al.

  • February 21, 2026

  • The Lancet
  • The Lancet, Volume 407, Issue 10530, Pages 784–793
  • 10.1016/S0140-6736(25)02319-0

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Evidence before this study

We searched the Cochrane Database of Systematic Reviews, which published a comprehensive analysis in 2023 evaluating the added value of ultrasonography to mammography in breast cancer screening. The review included eight studies: two prospective cohort studies, five retrospective cohort studies, and one randomised controlled trial (J-START), which was assessed to have low risk of bias. To identify any additional randomised controlled trials published since then, we conducted an updated search of the Cochrane Database of Systematic Reviews, as well as MEDLINE and PubMed on Aug 5, 2025 for studies published between Nov 22, 2014, and Aug 5, 2025, using keywords related to “breast cancer”, “screening”, “mammography”, “ultrasound”, and “randomised controlled trial”. This search identified the BRAID trial, in which abbreviated MRI and contrast mammography detected three times more invasive cancers than automated whole breast ultrasound. BRAID differs from J-START in age, modality, and follow-up.

Added value of this study

This report presents the extended follow-up results of J-START, a large-scale randomised controlled trial investigating the effect of adjunctive ultrasonography in breast cancer screening among women aged 40–49 years. Unlike previous reports, this analysis focused specifically on the cumulative incidence of advanced breast cancer. Our findings show that the addition of ultrasonography significantly reduced the incidence of advanced breast cancer for up to 8 years following the second screening. The study included 72 661 women followed up over more than 15 years (Aug 2, 2007, to Oct 4, 2024), with a minimal loss to follow-up. These results suggest that adjunctive ultrasonography with mammography is a highly effective strategy for the early detection of breast cancer in Asian women aged between 40 and 49 years with dense breast tissue, who are the target population of J-START.

Implications of all the available evidence

This study is the first randomised controlled trial to show a reduction in the cumulative incidence of advanced breast cancer, which could translate into decreased breast cancer mortality in the future. In cancer screening trials, mortality is often the most important endpoint; however, the favourable prognosis of breast cancer limits the number of mortality events that can be observed within a short follow-up period. Despite the fact that an observed reduction in advanced cancer might suggest a potential decline in mortality, the validity of using advanced cancer incidence as a surrogate endpoint remains under debate. Although current evidence is still limited, our findings might contribute to the use of advanced breast cancer incidence as a potential surrogate indicator. Continued follow-up is warranted to confirm whether adjunctive ultrasonography reduces breast cancer mortality.

Source: The Lancet

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