The LORIS trial is an ongoing clinical trial on low-risk ductal carcinoma in situ (DCIS). DCIS patients aged more than 46 years with screen-detected low/intermediate nuclear grade were considered low risk and were randomized into a surveillance or traditional surgery. This retrospective study was aimed to review the ten year breast cancer registry database and evaluate the clinical outcomes of low vs. high-risk patients. The setting of this study was a prospectively maintained territory-wide breast cancer registry in Hong Kong. Between the year 1997-2006, about 1391 breast cancer patients were identified from the Hong Kong cancer registry database.

Only 777 patients were termed to be at high-risk, whereas 372 patients were classified as low-risk. After a follow-up of 12 years, the total breast cancer-specific survival of the DCIS patients cohort was almost 99%. The survival of low-risk patients was 99.5%, whereas, for high-risk patients, it was 98.6%. About 93 patients in the LORIS high-risk group who didn’t undergo surgery, whereas there were 46 patients in the low-risk group. The ten years breast cancer patient survival in the low-risk  group was about 98%, whereas it was 97% for the high-risk DCIS group. In conclusion, DCIS’s long-term survival was excellent, especially in low-risk patients, regardless of surgical treatment.