BACKGROUND Mammography and physical examination are routine methods for the detection of ipsilateral local recurrence and contralateral breast carcinoma in patients initially undergoing breast conservation treatment. The current study reports the relation between the method of detection of the initial breast carcinoma and the method of detection of subsequent ipsilateral local recurrence and contralateral breast carcinoma. METHODS A retrospective review was performed of the records of female patients with initial American Joint Committee on Cancer (AJCC) Stage I and II invasive breast carcinoma who developed ipsilateral local recurrence or contralateral breast carcinoma after breast conservation treatment. The method of detection of local recurrence in the ipsilateral breast and the method of detection of contralateral breast carcinoma were compared with the method of detection of the primary tumor. RESULTS There were 125 ipsilateral breast local recurrences and 71 contralateral breast carcinoma cases detected. Of the 125 recurrences in the ipsilateral breast, 38% (48 recurrences) were detected by mammography only, 37% (46 recurrences) were detected by physical examination only, and 25% (31 recurrences) were detected by both methods. Of the 71 contralateral breast carcinoma cases, 53% (38 cases) were detected by mammography only, 23% (16 cases) were detected by physical examination only, and 24% (17 cases) were detected by both methods. When the primary tumors were detected by mammography only, 21% of the local recurrences (3 of 14 local recurrences) and 19% of the contralateral breast carcinoma cases (4 of 21 cases) were detected by physical examination only. When the primary tumors were detected by physical examination only, 24% of the local recurrences (14 of 58 local recurrences) and 42% of the contralateral breast carcinoma cases (8 of 19 cases) were detected by mammography only. When stratified by the interval between diagnosis of the primary tumor and ipsilateral local recurrence or contralateral breast carcinoma (< or = 5 years vs. > 5 years) or age of the patient at the time of ipsilateral breast recurrence or contralateral breast carcinoma (age < or = 49 years vs. age > or = 50 years), both breast examination and mammography were found to be important in the detection of locally recurrent tumor and contralateral breast carcinoma in each subgroup of the patients, regardless of the method of presentation of the primary tumor. CONCLUSIONS Both mammography and physical examination were found to be significant in the detection of locally recurrent tumor in the ipsilateral breast and in the detection of contralateral breast carcinoma, regardless of the method of detection of the primary tumor.