The significance of the internal mammary lymph nodes in medially located breast cancer.

The efficacy of adjuvant radiotherapy for medial breast cancers in Stage I or II disease was studied with a retrospective clinical analysis. All cases of breast cancer free of axillary node metastases at the time of standard or modified radical mastectomy were included. These were grouped by location and size of the primary tumor. There were 76 medial lesions, including those in the 6:00 or 12:00 axis. Seventeen of these had received postoperative radiation. Lateral tumors included 59. The size was based on the largest linear dimension and grouped less than or equal to 2 cm or greater than 2 cm. At the time of initial recurrence, all areas of metastases were determined. The data suggests that: (1) medial breast cancers have a greater rate of recurrence than lateral ones; (2) adjuvant radiation for medial lesions decreases that recurrence rate to the range of lateral tumors; (3) large lesions may have a greater chance for local recurrence as well as medial lesions of all sizes; and (4) the potential problems with local recurrence may be diminished with adequate radiotherapy as an adjunctive measure. When recurrence does occur, prior radiotherapy seems to delay the appearance of that recurrence.