Short-term and long-term survival of interval breast cancers taking into account prognostic features

The aim of this population-based study was to estimate short-term and long-term survival of interval breast cancers and to compare them to clinically detected cancers, taking into account prognostic features.

This study included all interval cancers and clinically detected cancers diagnosed in the Loire-Atlantique population-based cancer registry from 2000 to 2010 in women aged 50-76 years. We used the Pohar-Perme method to estimate 5- and 10 year net survival rates and a flexible parametric model to compare interval cancer and clinically detected cancer prognosis with and without adjustment for the main prognostic factors (age, stage, histological grade, and phenotype).

This study included 813 interval cancers and 1,354 clinically detected cancers. Interval cancers were diagnosed at a significantly less advanced stage than clinically detected cancers, but more often with a triple-negative phenotype. Interval cancer age-standardised net survival was 88.0% at 5 years (95% CI 84.9-91.2) and 81.7% at 10 years (95% CI 76.9-86.9), whereas clinically detected cancer age-standardised net survival was 77.8% (95% CI 75.1-80.6) and 64.6% (95% CI 60.7-68.7), respectively. After adjustment for covariates, survival no longer differed between interval cancers and clinically detected cancers at 5 and 10 years.

Although the interval cancer net survival rate was higher, interval cancers had a similar short-term and long-term prognosis than clinically detected cancers after taking into account the main prognostic factors.