Abstract
Objectives“True” breast cancers, defined as not being visible on prior screening mammograms, are expected to be more aggressive than “missed” cancers, which are visible in retrospect. However, the evidence to support this hypothesis is limited. We compared the risk of death from any cause for women with true, minimal signs, and missed invasive screen-detected (SDC) and interval breast cancers (IC).MethodsThis nation-wide study included 1022 SDC and 788 IC diagnosed through BreastScreen Norway during 2005–2016. Cancers were classified as true, minimal signs, or missed by five breast radiologists in a consensus-based informed review of prior screening and diagnostic images. We used multivariable Cox regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the risk of death from any cause associated with true, minimal signs, and missed breast cancers, adjusting for age at diagnosis, histopathologic tumour diameter and grade, and subtype. Separate models were created for SDC and IC.ResultsAmong SDC, 463 (44%) were classified as true and 242 (23%) as missed; among IC, 325 (39%) were classified as true and 235 (32%) missed. Missed SDC were associated with a similar risk of death as true SDC (HR = 1.20, 95% CI (0.49, 2.46)). Similar results were observed for missed versus true IC (HR = 1.31, 95% CI (0.77, 2.23)).ConclusionsWe did not observe a statistical difference in the risk of death for women diagnosed with true or missed SDC or IC; however, the number of cases reviewed and follow-up time limited the precision of our estimates.Key Points• An informed radiological review classified screen-detected and interval cancers as true, minimal signs, or missed based on prior screening and diagnostic mammograms.• It has been hypothesised that true cancers, not visible on the prior screening examination, may be more aggressive than missed cancers.• We did not observe a statistical difference in the risk of death from any cause for women with missed versus true screen-detected or interval breast cancers.
Highlights
Mammographic screening is considered the best approach to detect breast cancer at an early stage and thereby reduce breast cancer mortality [1, 2]
The radiologic classifications used in this study were obtained during a nationwide, multicentre informed review of ductal carcinoma in situ (DCIS) and invasive breast cancer diagnosed in BreastScreen Norway
True screendetected cancers had a higher proportion of grade 3 tumours (30.0%) than minimal signs (14.9%), or missed cancers (13.7%), and were more likely to be triple negative (9.8% versus 2.3% and 2.9%)
Summary
Mammographic screening is considered the best approach to detect breast cancer at an early stage and thereby reduce breast cancer mortality [1, 2]. Cancers that are retrospectively visible on prior screening mammograms are considered missed at the prior screen and the prior screening examination is considered a false negative Occult cancers are those that are not regarded as mammographically visible at diagnosis but may be symptomatic or diagnosed through other modalities such as ultrasound. The rates of these types of cancers in an organised screening program are associated with the sensitivity of the interpreting radiologists and that of any follow-up assessment, as well as the review process [12,13,14,15]
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