Abstract P3-17-10: The impact of the presence of ductal carcinoma in situ in patients with invasive ductal carcinoma
Authors: Xu L , Monga V , Thomas A , Leone JP 
Published: March 2017

Background: Ductal carcinoma in situ (DCIS) is considered to be a precancerous lesion that shares many genetic similarities with invasive ductal carcinoma (IDC). However, it remains unclear how DCIS might develop into IDC and whether the coexistence of DCIS has any clinical significance.There is limited data on whether coexisting DCIS in patients with IDC (IDC-DCIS) has any impact on patients' clinical presentation, tumor characteristics, prognosis and treatment selection. We aim to investigate differences in patients with pure IDC versus patients with IDC-DCIS.

Methods: We reviewed clinicopathologic data from the Breast Molecular Epidemiological Resource (BMER) database, which is a prospectively maintained breast cancer database from the University of Iowa. Missing information was supplemented by Iowa Cancer Registry database. Patients with a diagnosis of pure IDC and IDC-DCIS from 2009 to 2014 who underwent surgical resection of their breast cancer were included. We excluded patients with stage IV disease at diagnosis and those who underwent neoadjuvant therapy. Patients who had more than one tumor were only analyzed once using parameters of the largest tumor. Patient and tumor characteristics and treatment selection were compared between the IDC and IDC-DCIS groups. Student's t test was used for continuous variables and chi squared test for categorical variables.

Results: We observed that women with IDC-DCIS (n=226) had higher incidence of Her-2 positive cancers than those with pure IDC (n=95) (p=0.04). The IDC-DCIS group was more likely to be ER + and PR +, though these differences were not statistically significant. Another distinguishing characteristic between the two groups was that the IDC group contained more current smokers than the IDC-DCIS group (18.9% vs 10.6%, p&lt;0.01). Patients with IDC-DCIS were more likely, than patients with pure IDC, to be under-staged based on clinical information. Clinical stage distribution in IDC-DCIS group was: 4% stage 0, 61.9% stage I, 28.3% stage II and 5.8% stage III. In contrast, the percentages of pathologic stage I, II and III were 54.5%, 35.4% and 10.2%, respectively (p=0.002). Similar analysis for patients with pure IDC showed no significant overall change from clinical to pathologic stage. Patients with IDC-DCIS tended to have higher total mastectomy rates than patients with IDC (37.2% vs 31.6%, p=0.34). Management of patients in either group were not significantly different in terms of radiation, chemotherapy, or hormonal therapy. There were 4 deaths (4.2%) in the IDC group and 12 deaths (5.3%) in the IDC-DCIS group (p=0.68).

Conclusions: Our study showed that active smoking may be a risk factor for the development of IDC without pre-existing DCIS. Patients with IDC-DCIS had higher rates of Her-2 positivity and significant differences between clinical and pathologic stages. Management and survival of both groups were similar.

Citation Format: Xu L, Monga V, Thomas A, Leone JP. The impact of the presence of ductal carcinoma in situ in patients with invasive ductal carcinoma [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-17-10.