Risk factors for local recurrence after breast-conserving therapy

Background. Breast-conserving therapy has been widely accepted as a standard treatment for early breast cancer both in Western countries and in Japan. In Western countries, many studies have investigated the risk factors for local recurrence after breast-conserving therapy (BCT), but few such studies have been done in Japan. Methods. To determine the risk factors for local recurrence in 399 breast cancer patients (stage I and II, n = 396; stage III, n = 3) who had undergone BCT with or without postoperative radiation therapy, we evaluated their clinicopathological features by univariate and multivariate analyses. The patients were treated at Osaka National Hospital between February 1988 and December 1997. Results. Univariate analysis showed that a young age (≤45 years; P = 0.0005) was a significant risk factor for local recurrence, while radiation therapy (P = 0.0058) and adjuvant endocrine therapy (P = 0.0041) significantly reduced the risk of local recurrence. In patients with BCT, without radiation therapy a positive surgical margin significantly increased the risk of local recurrence (P = 0.0470). Multivariate analysis showed that a young age (P = 0.0285) was a significant independent risk factor for local recurrence, while radiation therapy (P = 0.0457) significantly decreased recurrence. In patients with a negative surgical margin, radiation therapy (P = 0.0158) and adjuvant endocrine therapy (P = 0.0421) significantly reduced the relative risk of local recurrence, to 0.160 and 0.366, respectively. In patients with a positive surgical margin, radiation therapy marginally significantly (P = 0.0756) reduced the relative risk of local recurrence, to 0.181, and adjuvant endocrine therapy significantly (P = 0.0119) reduced the risk, to 0.076. Conclusions. Young age and lack of radiation therapy or adjuvant endocrine therapy were risk factors for local recurrence in breast cancer patients treated with breast-conserving therapy, with surgical margin status also being a possible risk factor. Received: November 9, 1998 / Accepted: March 11, 1999