Characteristics of Screen-Detected Breast Cancer of Turkish Bahcesehir (Istanbul) Screening Project
Authors: Cabıoğlu Neslihan , Ozkan-Gurdal Sibel , Kayhan Arda , Ozaydın Ayse Nilufer , Şahin Cennet , Ozcinar Beyza , Aribal Erkin , Ozmen Vahit 
Published: October 2018

Purpose The Turkish Bahcesehir Breast Cancer Screening Project is a 10-year organized population-based screening program carried out in one of the largest counties of Istanbul, Turkey. The aim of the current study was to examine the biologic features of screen-detected and interval breast cancers for the first 9-year study period. Methods Between January 2009 and January 2018, 26,040 mammographies were performed with 2-year intervals for 8,408 women age 40 to 69 years. Clinicopathologic and biologic tumor characteristics—estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2-neu, and protein encoded by the MKI67 gene (Ki-67) —were analyzed for those patients who were diagnosed with breast cancer. Interval cancer was defined as symptomatic cancer diagnosed within 24 months of a negative screening. Ki-67 level > 20% was considered a high score. Results Median age was 52.5 years, and 37% were younger than age 50 years. Of 8,408 women, 113 breast cancers (1.3%) were detected. There were 14 ductal carcinoma in situ (12.4%) and 99 invasive cancers (87.6%). The majority of patients with invasive cancer had stage 1 (49.1%) or stage 2 (31.8%) disease. The majority of patients underwent breast-conserving therapy (83%) with sentinel lymph node biopsy alone (74.1%). Interval cancers (n = 11) were more likely to have multifocality or multicentricity ( P = .002) and high Ki-67 score ( P = .05). Furthermore, diagnosis with interval cancer was associated with more advanced disease, including stage II to IV disease and axillary positivity, and patients were more likely to have nonluminal cancers or tumors with lymphovascular invasion. However, these associations did not reach statistical significance. Multivariable logistic regression analysis identified multifocality or multicentricity as the only significant factor to be associated with interval cancers (odds ratio, 5.94; 95% CI, 1.4 to 25.4; P = .016). Conclusion Our findings suggest that the majority of screen-detected breast cancers exhibit either luminal A or B subtype with low Ki-67 scores and unifocal tumors. However, interval cancers were more likely to have aggressive biology and multicentricity that was less likely to be detected by mammographic screening programs and that required more aggressive surgical and systemic therapies. AUTHORS' DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST The following represents disclosure information provided by authors of this manuscript. All relationships are considered compensated. Relationships are self-held unless noted. I = Immediate Family Member, Inst = My Institution. Relationships may not relate to the subject matter of this manuscript. For more information about ASCO's conflict of interest policy, please refer to www.asco.org/rwc or ascopubs.org/jco/site/ifc . Neslihan Cabioğlu Research Funding: Roche (Inst) Travel, Accommodations, Expenses: Genomic Health Sibel Ozkan-Gurdal Research Funding: Roche (Inst) Arda Kayhan Research Funding: Roche (Inst) Ayse Nilufer Ozaydin Research Funding: Roche (Inst) Cennet Şahin Research Funding: Roche (Inst) Beyza Ozcinar Research Funding: Roche (Inst) Erkin Aribal Employment: Nutricia – Danone and TRPharm (I) Leadership: Nutricia – Danone and TRPharm (I) Stock or Other Ownership: Roche (I) Honoraria: GE Healthcare, Fuji, Roche Travel, Accommodations, Expenses: Bayer Vahit Ozmen Honoraria: Pfizer, Roche Research Funding: Roche (Inst), Genekor, Roche Travel, Accommodations, Expenses: Pfizer