['The pS2 protein is involved in the maintenance of the integrity of the gastrointestinal tract. In breast cancer pS2 can be demonstrated in at least half of the tumors and probably reflects the functional status of ER. Several features make it likely that pS2 is involved in growth regulation.', 'We have investigated the value of immunohistochemical pS2 determination as a prognostic factor in 339 breast cancer patients with long follow-up from one hospital.', 'A prognostic role for pS2 could not be demonstrated considering disease-free and overall survival, although in pS2-negative tumors a trend for less locoregional relapse was found. However, in multivariate analysis pS2 showed independent prognostic value for post-relapse survival.'] Is pS2 an independent prognostic factor for post-relapse survival in primary breast cancer?