Long-term Survival Outcomes of 'Low Risk' Ductal Carcinoma in situ from a Territory-wide Cancer Registry

Aims: The LORIS trial is an ongoing phase III clinical trial on low risk ductal carcinoma in situ (DCIS). DCIS patients aged >= 46 years with screen-detected low/ intermediate nuclear grade were considered low risk and were randomised into surveillance or standard surgery. Here we review the 10-year territory-wide breast cancer registry database and evaluate the clinical outcomes of low versus high risk DCIS patients. Materials and methods: This was a retrospective study of a prospectively maintained territory-wide breast cancer registry in Hong Kong. Results: Between 1997 and 2006, 1391 DCIS patients were identified from the Hong Kong cancer registry breast cancer database. The mean age at diagnosis was 49.2 years (range 30-70). In total, 372 patients were classified as low risk', whereas the remaining 777 patients were classified as 'high risk'. After a median follow-up of 11.6 years, the 10-year overall breast cancer-specific survival of the entire DCIS cohort was 1136/1149 (98.9%). Overall breast cancer-specific survival of low risk DCIS was 99.5%, whereas that in high risk DCIS was 98.6% (Log-rank test, P = 0.208). Forty-six (12.4%) patients in the LORIS low risk group did not receive surgery, whereas 93 (12%) patients in the LORIS high risk group did not receive surgery. The 10-year breast cancer-specific survival in the non-operated low risk DCIS group was 97.8%; that in the non-operated high risk DCIS group was 96.7% (P = 1). Conclusion: Long-term survival of DCIS was excellent, especially in low risk DCIS, regardless of surgical treatment. (C) 2020 Published by Elsevier Ltd on behalf of The Royal College of Radiologists.