ERBB2 and breast cancer: Analyses by the status of ER and HER2 jointly showed that lifetime MET-hours of physical activity were associated with decreased risks for the HER2− subtypes (ER−/HER2− and ER+/HER2− breast cancers), but only the result for ER+/HER2− was statistically significant (Table3, Ptrend = 0.01 for ER+/HER2−).