J. Timbres (London, United Kingdom)
King's CollegeAuthor Of 1 Presentation
82P - Predicting invasive disease and lymph node involvement in patients with preoperative diagnosis of ductal carcinoma in situ
Abstract
Background
Eight to 56% patients undergoing a mastectomy with preoperative diagnosis of ductal carcinoma in situ (DCIS) upgrade to invasive disease on final histopathological evaluation. Sentinel node biopsy in this cohort of patients cannot be safely excluded due to the high probability of finding invasive disease on final histopathological evaluation. We were keen to identify factors predictive of invasiveness and therefore probable nodal involvement.
Methods
We performed a retrospective audit of patients undergoing a mastectomy as primary treatment following a diagnosis of DCIS between Jan 2016 and Sept 2020 (n=99). We included patients diagnosed with DCIS that had normal conventional imaging following a microdochectomy for pathological nipple discharge, as well. We interrogated our data to identify predictors of invasiveness.
Results
29 of 99 patients were found to have invasive disease on final histopathological evaluation. Median pathological size of the DCIS was 60 mm (range of 10 to 180 mm). Nine patients (9.09%) were found to have involved lymph node involvement (5 micrometastases + 4 Macrometastases). Of the patients with invasive disease, 2 (6.8%) had low grade DCIS and 4 (13.7%) had intermediate grade DCIS. A higher proportion (53.8%) of those with distortion on 3D mammogram were found to have invasive disease as compared to those with micro-calcifications (25.5%; p=0.035). A smaller proportion of ER-negative DCIS were found to have invasive disease as compared to ER-positive (17.8% for ER-negative Vs 33.8% ER-positive), the difference was not statistically significant.
Conclusions
This study shows that over 71% of patients who underwent mastectomy for a preoperative diagnosis of DCIS with sentinel node biopsy that could have been avoided. Further research is needed to identify a cohort of patients with a pre-operative diagnosis of DCIS, where routine surgical staging of the axilla can be avoided to reduce additional surgical morbidity.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.