P. Singh1, M. Miller2, C. Wang4, D. J. Winchester3, C. Pesce3, E. Barrera3, K. Yao3 1University Of Chicago,Surgery,Chicago, IL, USA 2Memorial Sloan-Kettering Cancer Center,Surgery,New York, NY, USA 3Northshore University Health System,Surgery,Evanston, IL, USA 4Northshore University Health System,Center For Biomedical Research Informatics,Evanston, IL, USA
Introduction: A clinical trial in Europe is randomizing low-grade ductal carcinoma in situ (DCIS) patients to surgery versus no surgery arms and a similar trial will start soon in the United States. We utilized the National Cancer Database (NCDB) and the Surveillance, Epidemiology, and End Results (SEER) retrospective databases to examine overall (OS) and disease-specific (DSS) survival between patients who underwent surgical excision of DCIS versus those patients who did not undergo excision.
Methods: The NCDB and SEER databases were queried for low-grade DCIS patients treated from 2004-2011. We examined OS from both databases and DSS from SEER alone and used Cox regression modeling to adjust for patient, tumor and treatment factors. Mean follow-up for the surgery group was 5.6 years and 5.1 years for the no surgery group.
Results: Of 150,479 low-grade DCIS patients from the NCDB, 2,470 (2.0%) were reported to have no surgery and of 17,342 low-grade DCIS patients from SEER, 443 (2.5%) had no surgery. The mean age of the surgery group for NCDB and SEER was 58.8 and 58.4 years respectively and for the no surgery group was 60.4 and 60.8 years respectively. Mean tumor size was 1.5cm and 1.6cm for the NCDB and SEER patients respectively who had surgery, and 1.8cm and 1.5cm respectively for those who did not have surgery. Estrogen receptor was positive in 82.5% and 83.3% of the NCDB and SEER patients who had surgery and 82.1% and 85.8% of the NCDB and SEER patients who did not have surgery. In the NCDB and SEER patients undergoing surgery, 48.3% and 52.8% had radiation therapy versus 16.7% and 7.9% of those not undergoing surgery. Of NCDB patients, 33.1% of the surgery group received hormonal therapy compared to 11.7% in the no surgery group. OS at 10 years for both NCDB and SEER patients was greater for those who had surgery versus those who did not; in SEER, DSS was greater in the surgery group (Table 1). On Cox regression modeling adjusting for patient, tumor and treatment factors, not having surgery was associated with a 2.07 (95%CI: 1.73-2.46, p<0.001) greater risk of death in the NCDB and a 2.05 (95%CI: 1.63-2.59, p<0.001) greater risk of death in the SEER patients. The hazard ratio for DSS was 6.37 (95%CI: 3.8-10.6, p<0.0001) in SEER. Similar findings were found for estrogen receptor-positive patients alone.
Conclusion: OS and DSS were significantly higher in the surgery group versus the no surgery group. Although findings were similar between the two databases, selection bias may account for the survival differences between the surgery and no surgery groups given the retrospective nature of the databases. Future clinical trials will be more definitive in determining survival outcomes in DCIS patients not undergoing surgery.
