Breast cancer survival and prognosis by screening history.

BACKGROUND

Cancers not detected by breast screening are commonly assumed to have poorer prognosis.

METHODS

We examined the survival experience of all women aged 50-74 years diagnosed with a first breast cancer between 1998 and 2006 in British Columbia, Canada and determined their screening experience. Disease-specific survival rates were calculated and, for cases diagnosed in 2002, prognostic factors (size, nodal involvement, grade ER status and stage) were examined by time since screening.

RESULTS

Breast cancers diagnosed at screening had the best survival (P<0.001). Cancers detected within 12 months of a negative screen had similar survival rates (P=0.98) to those diagnosed within 12-23 and 24-47 months, with other non-screen-detected cancers having poorer survival (P<0.001). The prognostic profile of cancers diagnosed in 2002 followed a similar pattern.

INTERPRETATION: There was no evidence that cancers diagnosed within 12 months had poorer prognosis than those diagnosed up to 48 months following screening.