Brachytherapy in breast cancer: factors predictive of local and distant recurrence

This study aims to evaluate predictive factors of local recurrence and distant metastasis in patients submitted to brachytherapy as a complementary treatment of breast cancer after surgeries. It is justified as a search for production of knowledge regarding the adjuvant treatment in breast cancer and identification of phenotypes that may be related to the better therapeutic response in patients submitted to brachytherapy with multiple catheters. Methodologically, the study was organized as a retrospective cohort with a convenience sample. It counts on the participation of patients diagnosed with precursor lesions or invasive breast neoplasm in initial clinical staging, classified as 0, I and IIA, submitted to breast brachytherapy as an adjuvant treatment to surgery. Data from medical records were collected at the Radium Institute of Campinas between March 2004 and June 2013, with 377 patients receiving partial accelerated partial breast irradiation (APBI) using multiple catheters as adjuvant therapy to breast conserving surgery. Eighty percent of these patients had the diagnosis of invasive carcinoma and 20% of ductal carcinoma in situ. The pathological staging was thus distributed: 0: 20%, I: 68% and II: 12%. Most of the patients had estrogen receptor positive (86%) and progesterone receptor positive (79%), HER2 negative (82%) and 63% had degree of tumor differentiation. Data were collected with local recurrence events and distant metastasis. The mean follow-up time was 50.5 months. The mean age of the patients was 59 years. The mean tumor size was 1.37 cm. Local recurrence was present in 12 patients (3.18%) and distant metastasis was recorded in seven patients (1.86%). Follow-up at 2 years, 5 years and 10 years presented a free recurrence rate of 99.3%, 97.1% and 83.8%, respectively. In univariate analysis, Her2 negative (OR: 16.42, 95% CI: 1.63-165.13, p = 0.01) and estrogen and progesterone receptors (OR: 4.17, 95% CI: 1.30-13.36, p = 0.01) were statistically significant in local recurrence. We conclude, therefore, that the accelerated partial irradiation of the breast with brachytherapy with the use of multiple interstitial catheters is a safe technique for adjuvant treatment in a select group of patients with diagnosis of initial breast cancer. Locoregional disease control presented excellent rates and low toxicity. In univariate analysis, Her2 positive and estrogen receptor and progesterone negative cases were statistically significant for local recurrence. (author)