Contralateral breast cancer: factors associated with stage and size at presentation.

Few reports have evaluated factors associated with the stage at presentation of contralateral breast cancer and whether contralateral cancer presentation has changed in recent years, during which increased screening and enhanced adjuvant therapy of the initial tumor has been introduced. Patients with initial cancers staged 0-IIIB diagnosed between 1980 and 1999 who subsequently developed contralateral breast cancer were evaluated for stage, primary tumor size and histologic features, patient age and year of diagnosis, synchronous or metachronous presentation, and time from initial tumor to diagnosis of contralateral breast cancer. Tumor presentation was compared with contemporaneously diagnosed unilateral breast cancer patients. A total of 171 patients were diagnosed with contralateral breast cancer; 161 cases if lobular carcinoma in situ for either the initial or the contralateral tumor were excluded. Contralateral tumors were of significantly smaller size and of earlier stage than initial tumors. Contralateral cancers demonstrated earlier stage distributions with more recent year of diagnosis; initial tumors in contralateral patients did not. Earlier stage at presentation of contralateral tumors was associated in a multivariate model with more recent year of contralateral tumor diagnosis and earlier stage at presentation of the initial tumor; contralateral tumor size was associated with the size of the initial tumor. More recently diagnosed contralateral breast cancers are presenting with earlier stages of disease. The stages of initial tumors in these patients have not undergone such an improvement. Initial tumor size and stage is strongly associated with contralateral breast cancer size and stage; this association is independent of the year of diagnosis. Increased compliance with screening might be expected to improve both initial tumor stage and tumor size presentations in contralateral tumor patients, as well as the presentation of contralateral cancers.