Prognostic impact of the early detection of metachronous contralateral breast cancer.

The study aimed to assess whether the early detection of asymptomatic metachronous contralateral breast cancer (MCBC) improves the prognosis of the patient compared with a diagnosis at symptomatic onset. We reviewed 339 MCBC cases that were consecutively diagnosed from 1970 to 2001, for which reliable information on subjective symptoms was available. The association of early (asymptomatic vs. symptomatic) detection with mortality from breast cancer was studied by univariate and multivariate analyses, adjusting for potential confounders. A more favourable stage at diagnosis was evident for asymptomatic vs. symptomatic MCBC (pT1=84.2% vs. 58.1%, pN0 65.0% vs. 52.4%). The hazard ratio (HR) of breast cancer death was approximately half (0.49%, 95% Confidence Interval (CI) 0.29-0.83, P = 0.008) for asymptomatic vs. symptomatic MCBC. Although length bias may have occurred (symptomatic MCBC had a shorter free interval from the first cancer), the present evidence supports the practice of active follow-up aimed at the early detection of asymptomatic MCBC.