ARRS 2022 Abstracts

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1844. Ipsilateral Recurrence Following Breast-Conserving Surgery for Ductal Carcinoma In Situ: Evaluation of Risk Prediction Models
Authors * Denotes Presenting Author
  1. Kimberlee Hashiba *; Harvard Medical School; Massachusetts General Hospital
  2. Manisha Bahl; Harvard Medical School; Massachusetts General Hospital
Objective:
The incidence of ductal carcinoma in situ (DCIS), also known as non-invasive or stage 0 breast cancer, has markedly increased since the widespread implementation of screening mammography. Treatment of DCIS involves some combination of surgery, radiation, and hormonal treatment, with the goal of determining the least aggressive treatment needed to minimize the risk of a future ipsilateral breast cancer recurrence. The purpose of this study is to determine ipsilateral breast recurrence risks in women with DCIS who have undergone breast-conserving surgery (BCS), as estimated by the Van Nuys Prognostic Index and the Memorial Sloan Kettering Cancer Center (MSKCC) DCIS nomogram.

Materials and Methods:
In this Institutional Review Board-approved and HIPAA-compliant study, medical records were reviewed for consecutive women diagnosed with DCIS by image-guided core needle biopsy from 2007 - 2014 at an academic medical center. Included patients underwent BCS and had at least 5-year imaging follow-up. The following women were excluded from the analysis: women with a concurrent diagnosis of invasive cancer, upstaged invasive disease at surgery, a prior history of breast cancer, or less than 5-year imaging follow-up. For each patient who had an ipsilateral recurrence, the Van Nuys Prognostic Index and MSKCC DCIS nomogram risk estimates were calculated. In addition, imaging and clinicopathological features were compared between women who did and did not have a recurrence using the Pearson’s chi-squared test and the Wilcoxon signed-rank test.

Results:
Over an 8-year period, 456 women (mean age 57 years, range 30-87 years) underwent BCS for DCIS. Most women were also treated with radiation (89.5%, 408/456), and one-quarter (25.2%, 115/456) completed at least 5 years of adjuvant endocrine therapy. Of 456 women, 31 (6.8%) experienced an ipsilateral recurrence (18 invasive cancers and 13 DCIS). The median and mean time periods from initial DCIS diagnosis to subsequent recurrence were 4.5 years and 5.5 years (standard deviation of 3.0 years), respectively. Among the 31 women who had a recurrence, the average Van Nuys Prognostic Index score was 7.4 (range 5-10), with 4-6 being the lowest risk group, 7-9 moderate risk, and 10-12 high risk. Per the MSKCC nomogram, the average 5-year risk of recurrence was 5% (range 1-12%). Two of the features found to be significantly associated with recurrence risk in our patient cohort but not included in either of the risk prediction models are dense breast tissue on mammography (80.6% [25/31] vs 53.6% [228/425], p<0.01) and estrogen receptor-negative status at biopsy (17.9% [5/28] vs 6.3% [25/398], p=0.02).

Conclusion:
Ipsilateral recurrence risk estimates based on the Van Nuys Prognostic Index and MSKCC DCIS nomogram vary among women with DCIS who underwent BCS and developed a subsequent recurrence. Inclusion of imaging features such as dense breast tissue on mammography and pathological features such as estrogen receptor status could potentially strengthen these risk prediction models.