Although there have been encouraging recent studies showing a potential benefit from annual mammography in women aged 40-49 years of age with an elevated breast cancer risk due to family history there is little evidence of efficacy in women aged <40 years of age. A prospective study (FH02) has been developed to assess the efficacy of mammography screening in women aged 35-39 years of age with a lifetime breast cancer risk of ≥ 17 % who are not receiving MRI screening. Retrospective analyses from five centres with robust recall systems identified 47 breast cancers (n = 12 in situ) with an interval cancer rate of 15/47 (32%). Invasive tumour size, lymph node status and current vital status were all significantly better than in two control groups of unscreened women (including those with a family history) recruited to the POSH study. Further evaluation of the prospective arm of FH02 is required to assess the potential added value of digital mammography and the cancer incidence rates in moderate and high risk women in order to inform cost effectiveness analyses.
Background
Many women who are at increased risk of breast cancer due to a mother or sister diagnosed with breast cancer aged under 40 do not currently qualify for surveillance before 40 years of age. There are almost no available data to assess whether mammography screening aged 35–39 years would be effective in this group, in terms of detection of breast cancer at an early stage or cost effective.
Methods
A cohort screening study (FH02) with annual mammography was devised for women aged 35–39 to assess the sensitivity and screening performance and potential survival of women with identified tumours.
Findings
2899 women were recruited from 12/2006–12/2015. These women underwent 12,086 annual screening mammograms and were followed for 13,365.8 years. A total of 55 breast cancers in 54 women occurred during the study period (one bilateral) with 50 cancers (49 women) (15 CIS) adherent to the screening. Eighty percent (28/35) of invasive cancers were ≤ 2 cm and 80% also lymph node negative. Invasive cancers diagnosed in FH02 were significantly smaller than the comparable (POSH-unscreened prospective) study group (45% (131/293) ≤ 2 cm in POSH vs 80% (28/35) in FH02 p < 0.0001), and were less likely to be lymph-node positive (54% (158/290, 3 unknown) in POSH vs 20% (7/35) in FH02: p = 0.0002. Projected and actual survival were also better than POSH. Overall radiation dose was not higher than in an older screened population at mean dose on study per standard sized breast of 1.5 mGy.
Interpretation
Mammography screening aged 35–39 years detects breast cancer at an early stage and is likely to be as effective in reducing mortality as in women at increased breast cancer risk aged 40–49 years.
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