Long-Term Survival Following Definitive Radiation Therapy for Oligometastases in Gynecological Malignancies: A Landmark Analysis

Abstract

Radiation therapy (RT) has been shown to prolong survival for patients with select oligometastatic cancers. Limited long-term follow-up data exist to determine if the prolonged survival correlates with cure versus a delayed relapse. To investigate this, we evaluated the clinical and disease characteristics of long-term survivors treated with definitive RT for oligometastatic gynecological cancer at our institution.We performed a landmark analysis in patients with oligometastatic gynecological cancer (OMGC) who survived for at least 5 years following treatment of their metastasis. OMGC was defined as metastasis (maximum of 5 total and 3 per site) present at a distant site at time of diagnosis or at a regional or distant site at time of recurrence. All patients received definitive RT between 2000 and 2015. Demographic and clinical variables were extracted from the medical record. Disease-free survival (DFS) after treatment of the first ROMGC was modeled using Kaplan Meier curves.48 patients with OMGC were analyzed; 20 (41.7%) had ovarian cancer, 16 (33.3%) had uterine cancer, 11 (22.9%) had cervical cancer, 1 (2.1%) had vaginal cancer. Median age was 52 years. A majority (45.8%) were stage III at primary diagnosis. The most common histology was adenocarcinoma (35.4%). The most common site of OMGC was in the pelvic lymph nodes (LN) (40.7%), with the following other sites: para-aortic LN (38.9%), supraclavicular LN (7.4%), lung (5.6%), mediastinal LN (3.7%), and axillary LN (3.7%). The median size was 2 cm. The median [interquartile range (IQR)] total RT dose and fractionation was 62.1 [52.5-64.5] Gy and 2.1 [2-2.2] Gy/fraction. The majority (70.8%) were treated with intensity-modulated RT. 25 (52.1%) patients received concurrent chemoRT (CRT) for their OMGC. After a median follow-up of 9.9 years after OMGC treatment, median [range] DFS for all patients was 73 [4-212] months (mo). 5-year DFS for cervical, uterine, and ovarian cancers was 82% (95% confidence interval [CI], 45-95%), 69% (CI, 41-86%), and 35% (CI, 16-55%), respectively. Patients who received CRT had better median DFS than those treated with RT alone (103 vs. 65 mo, P = 0.18). Patients with nodal OMGC had similar median DFS as those with non-nodal OMGC (73 vs. 66 mo, P = 0.86). During the first OMGC course, patients treated for 1 site had worse median DFS than those treated for 2+ sites (65 vs. 103 mo, P = 0.61). Of all 48 patients, 8 (16.7%) died of gynecologic cancer, 11 (22.9%) died of other causes, 3 (6.3%) had progression of disease. The remaining 26 (54.2%) patients were disease free at long-term follow up.Cure is possible for patients treated definitively for OMGC. Patients with cervical cancer, a greater number of treated OMGC sites, and treated with CRT had the longest DFS among this selected cohort. A randomized trial in oligometastatic gynecologic cancer is needed to determine if RT increases overall survival.K.L. Corrigan: None. A.K. Yoder: None. L.L. Lin: Employee; VA Hospital. Research Grant; Astra Zeneca. Travel Expenses; Astra Zeneca. A. Jhingran; American Board of Radiology. M.M. Joyner: Consultation with executive management and participation in board meetings; Frontline Bioenergy. P.J. Eifel: Travel Expenses; National Cancer Center Network. Stock; Apple Computer. L. Colbert: None. K.H. Lu: None. A.H. Klopp: Research Grant; MD Anderson Cancer Center SPORE Grant.