Validation of radiation volume by analysis of recurrence pattern in breast-conserving treatment for early breast cancer

Purpose: To assess the appropriateness of radiotherapy volume for patients receiving breast-conserving treatment (BCT) through analysis of recurrence pattern and factors affecting recurrence. Methods: From 1991 to 1996, 362 patients who received BCT were retrospectively evaluated. The radiation volume was the involved breast alone in the patients with less than 4 positive axillary lymph nodes (LNs), and breast and supraclavicular fossa in patients with 4 or more positive axillary LNs. The median follow-up period was 123 months (range, 3-169 months). Results: Ten-year overall, disease-free, local recurrence-free, and regional recurrence-free survival rates were 86.2%, 82.2%, 95.9%, and 95.2%, respectively. Among 310 patients receiving radiotherapy on the breast alone, 15 (4.8%) had regional recurrence. In particular, patients with inner quadrant lesions had high regional recurrence rates (11/98, 11.2%) (p <0.001). Conclusion: These low local recurrence rates may reveal that the current radiotherapy technique was successful. However, in cases of inner quadrant lesions, there were a considerable number of regional recurrences, even in N0 cases. This may suggest a potential role for irradiation on regional LNs in this group.