Michael T Milano1, Alan W Katz2, Hong Zhang2, Christine F Huggins2, Khush S Aujla2, Paul Okunieff3. 1. Department of Radiation Oncology, University of Rochester, United States. Electronic address: michael_milano@urmc.rochester.edu. 2. Department of Radiation Oncology, University of Rochester, United States. 3. Department of Radiation Oncology, University of Florida, Gainesville, United States.
Abstract
BACKGROUND: The clinical state of oligometastases describes metastases limited in number and extent, amenable to metastasis-directed therapy. We sought to analyze long-term outcomes and characterize potential prognostic factors, in women with breast cancer (BC) oligometastases treated with hypofractionated stereotactic radiation (HSRT) therapy on a prospective phase II protocol. METHODS: Forty-eight women with 1-5 extracranial BC oligometastases received HSRT to all radiographically apparent sites of disease. Various dose-fractionation schedules were used. Most (n = 27) received 10 daily fractions, typically ≥50 Gy (n = 17). RESULTS: BC patients with bone-only oligometastases (BO, n = 12) vs. all other patients (non-BO; n = 36) were significantly younger, more likely to present with oligometastases at the time of primary BC diagnosis (i.e., synchronous), and significantly more likely to have had hormone receptor-positive disease. The 5-year and 10-year overall survival (OS) rates after HSRT were 83% and 75%, respectively, for BO patients vs. 31% and 17%, respectively, for non-BO patients (p = 0.002). BO patients experienced a significantly (p = 0.018) greater freedom from widespread metastases (FFWM). Among non-BO patients, net oligometastatic GTV >25 cc (reflecting disease burden) was a significant factor for freedom from local recurrence (p = 0.047) and FFWM (p = 0.028). The number of oligometastatic lesions (p = 0.007) and organs (p = 0.001) involved were also significant factors for FFWM in non-BO patients. CONCLUSIONS: Some patients with BC oligometastases treated with HSRT can survive >10 years. Tumor burden (volume and number of lesions) appears to impact risk of recurrence. Further research is needed to help better identify BC patients most likely to benefit from metastasis-directed radiotherapy.
BACKGROUND: The clinical state of oligometastases describes metastases limited in number and extent, amenable to metastasis-directed therapy. We sought to analyze long-term outcomes and characterize potential prognostic factors, in women with breast cancer (BC) oligometastases treated with hypofractionated stereotactic radiation (HSRT) therapy on a prospective phase II protocol. METHODS: Forty-eight women with 1-5 extracranial BC oligometastases received HSRT to all radiographically apparent sites of disease. Various dose-fractionation schedules were used. Most (n = 27) received 10 daily fractions, typically ≥50 Gy (n = 17). RESULTS: BC patients with bone-only oligometastases (BO, n = 12) vs. all other patients (non-BO; n = 36) were significantly younger, more likely to present with oligometastases at the time of primary BC diagnosis (i.e., synchronous), and significantly more likely to have had hormone receptor-positive disease. The 5-year and 10-year overall survival (OS) rates after HSRT were 83% and 75%, respectively, for BO patients vs. 31% and 17%, respectively, for non-BO patients (p = 0.002). BO patients experienced a significantly (p = 0.018) greater freedom from widespread metastases (FFWM). Among non-BO patients, net oligometastatic GTV >25 cc (reflecting disease burden) was a significant factor for freedom from local recurrence (p = 0.047) and FFWM (p = 0.028). The number of oligometastatic lesions (p = 0.007) and organs (p = 0.001) involved were also significant factors for FFWM in non-BO patients. CONCLUSIONS: Some patients with BC oligometastases treated with HSRT can survive >10 years. Tumor burden (volume and number of lesions) appears to impact risk of recurrence. Further research is needed to help better identify BC patients most likely to benefit from metastasis-directed radiotherapy.
Authors: Tessa G Steenbruggen; Michael Schaapveld; Hugo M Horlings; Joyce Sanders; Sander J Hogewoning; Esther H Lips; Marie-Jeanne T Vrancken Peeters; Niels F Kok; Terry Wiersma; Laura Esserman; Laura J van 't Veer; Sabine C Linn; Sabine Siesling; Gabe S Sonke Journal: JNCI Cancer Spectr Date: 2021-02-04