Targetable mutations more common with both breast, uterine cancer

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Takeaway

  • Women with both breast and uterine cancer (BUC) are more likely to test positive for germline mutations than women who have breast cancer (BCa) alone or uterine cancer (UC) alone.

Why this matters

  • One of the first studies of multigene testing in BUC.
  • The majority of identified mutations identified were actionable, suggesting that women with BUC should be offered expanded genetic testing. 

Study design

  • Study of women (n=51,918) tested for 23 BCa or UC genes, including 1650 with BUC.
  • Funding: None disclosed.

Key results

  • 1 or more mutations in the 23 genes were found in 14.0% of BUC vs 9.3% of BCa only (P<.001 of uc only and with no cancer>
  • BUC cases (n=730) were more likely than no cancer cases (n=19,597) to have mutations in ATM, BARD1, BRCA2, MSH2, MSH6, PALB2, PMS2, and PTEN (P<.01 except>BARD1, PTEN: P=.02).
  • BUC cases were more likely than BCa only (n=30,148) to have mutations in BRCA1, MLH1, MSH2, MSH6, PMS2, and PTEN (all P<.01>
  • BUC cases were 2 times more likely to have BRCA1 mutations (OR, 2.01; P=.016)
  • BUC cases were more likely than UC only (n=1307) to have ATM mutations (OR, 5.27; P=.01).
  • Limitations

    • Retrospective design.
    • Single testing laboratory used.