Interstitial high dose rate (HDR) brachytherapy for early stage breast cancer

Abstract

10551 Background: External Beam Radiation Therapy (EBRT) has been the standard of care for breast conservation radiation therapy. Recent data indicates that Interstitial Implant and High Dose Rate (HDR) radiation afterloading compares favorably to EBRT in selected patients. Methods: Patients with Tis, T1, and T2 tumors measuring ≤ 3 cm, negative surgical margins, and negative axillary lymph nodes were judged to be candidates for Interstitial Implant. Results: Between 2000 and 2006, 112 patients underwent Interstitial HDR Implant under Stereotactic Mammographic guidance with conscious sedation and local anesthesia. Conscious sedation consisted of Morphine and Versed. Local anesthesia was given with a mixture of 1% Lidocaine, 0.25% Marcaine, 1:100,000 Epinephrine, and 4% Sodium Bicarbonate neutralizing solution. The implants were placed using a Template with from 3 to 6 planes, and 8 to 43 needles. Catheters were subsequently threaded thru the needles, and the needles removed. Catheter spacing was 1.0 to 1.5 cm. Radiation Treatment planning was performed using CT Scanning. Treatment volumes ranged from 25 cm3 to 359 cm3. The breast implant volume received 3400 cGy in 10 fractions via HDR prescribed to the Planning Target Volume, given BID over 5 days. The procedure was well tolerated. No patient required hospital admission. With a median follow-up 36 months (range 6–60 months), local recurrence occurred in 2.7% (3/112). Cosmetic results were good to excellent in 85.7% (96/112) of the patients. Wound healing complications developed in 7.1% (8/112). Three of these patients had received anthracycline based Chemotherapy. The other five had large (> 200 cm3) implant volumes and catheter spacing of 1.5 cm. Two patients healed after 6 months of conservative treatment. Surgery was required in six patients who developed fat necrosis. Conclusions: With median 36 month follow-up, Breast Conservation radiation therapy utilizing Interstitial HDR Implant has yielded local recurrence rates and cosmetic results which compare favorably to EBRT in selected patients. Treatment with anthracycline based Chemotherapy and large (> 200 cm3) implant volumes appear to be relative contraindications to Interstitial HDR Implant. Finally, catheter spacing of 1 cm yielded optimal dosimetry and minimized complications. No significant financial relationships to disclose.