Abstract 99P
Background
Predicting DCIS recurrence remains challenging. Our study validates local recurrence risks in DCIS patients based on criteria from landmark and ongoing trials, aiming to aid treatment decisions and develop a novel prediction model.
Methods
Analyzing patients diagnosed with DCIS who underwent breast-conserving surgery at our institution over a span of 20 years, from 1999 to 2021. We assessed recurrence risk using Kaplan-Meier estimates. Rates of initial local recurrence were compared across various trial recommendations and eligibility criteria. We used penalized Cox regression and reported AuROC to assess predictive performance.
Results
Our study comprised 600 DCIS patients, with median follow-up durations of 10.69 and 6.76 years in recurrence and non-recurrence groups, respectively. Among them, 71 patients experienced a first local recurrence (11.80%). Recurrence included DCIS in 36 cases (50.70%) and invasive cancer in 35 cases (49.30%). Most recurrences were ipsilateral (53 cases, 74.60%), followed by contralateral (16 cases, 22.50%), and bilateral (2 cases, 2.80%) breast tumor recurrence. In the table: LORD showed the lowest risk (0% over 10 years) with grade 1 histology. LORETTA, including up to grade 2 histology, tumor size ≤ 2.5 cm, and ER positivity, demonstrated the second lowest risk (6.7% over 10 years). These findings prioritize grade 1 histology, followed by tumor size ≤ 2.5 cm and ER status. Our preliminary analysis found three significant variables: hormonal treatment, tumor grade, and re-wide excision using penalized Cox regression. Radiotherapy notably predicted lower local recurrence rates. Table: 99P
| IIBTR from Landmark or Ongoing trials | Total | Low | High | HR | C-index | |
| RTOG 9804 10 year 15 year | 600 | 94 (16%) 8.4% 21.7% | 506 (84%) 16.2% 21.7% | 1.60 (0.73-3.46) p=0.239 | 0.53 | |
| COMET 10 year 15 year | 600 | 195 (32.5%) 10.4% 24.9% | 405 (67.5%) 17.3% 21.3% | 1.58 (0.90-2.76) p=0.110 | 0.58 | |
| LORD 10 year 15 year | 600 | 19 (3%) 0% 0% | 581 (97%) 15.7% 22.9% | NA | NA | |
| LORETTA 10 year 15 year | 600 | 59 (10%) 6.7% 15.2% | 541 (90%) 16.0% 22.5% | 1.96 (0.71-5.38) p=0.191 | 0.54 | |
| LORIS 10 year 15 year | 600 | 64 (11%) 9.1% 16.0% | 536 (89%) 15.9% 22.6% | 1.46 (0.63-3.36) p=0.379 | 0.53 | |
| Low1 | Low2 | High | ||||
| ECOGAcrinE5194 10 year 15 year | 600 | 302 (50%) 14.9% 24.8% | 105 (18%) 13.6% 18.7% | 193 (32%) 16.1% 18.2% | High vs Low1 1.17 (0.71-1.95) p=0.539 High vs Low2 1.43 (0.67-3.07) p=0.348 | 0.56 |
Conclusions
Based on our 10-year data validation, Grade 1 histology, tumor size ≤ 2.5 cm, and ER-positive status are key in identifying low recurrence risk. Factors like no re-wide excision and radiotherapy may also reduce recurrence. Future plans include refining risk assessment in DCIS patients with a prediction model.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.