Abstract B06: Circulating tumor cell analysis in locally and advanced colon cancer: A pilot study

Abstract

Colorectal cancer presents high incidences (9.7%) and mortality rates (8.5%) worldwide in men and women. Although the early detection of colon cancer promotes high cure rates (30-40%), there are still patients who experience local recurrence as well as distant metastases. The main treatment is surgery-based and then, after risk evaluation, patients can undergo or not undergo adjuvant chemotherapy. Circulating tumor cells (CTCs) and circulating tumor microemboli (CTM) seem to play an important role in these processes, being detached from tumor and circulating in blood vessels before surgery intervention. Our objective, therefore, was to evaluate the role of CTCs and CTM in stages I-III colon cancer patients. Here, we collected 10 mL of blood from presurgery colon cancer and filtrated the sample in ISET® (Isolation by Size of Epithelial Tumor cells) device. This study started on July 2016. CTCs counts were assessed and correlated with clinical and pathologic data. We included 15 patients. However, one patient was identified as metastatic after surgery and therefore excluded from these analyses. From 14 patients analyzed, 8 (57.1%) were male, with a median age of 65 years (53-87). The most prevalent cancer sites were right colon (n= 6;42.9%) and left colon (n=4;28.6%). CTCs detection rate was 85.7%, and the mean and median of CTCs were 5.1/mL and 2.6/mL, respectively (0-30.3/mL). We found CTM in 4/14 patients (28.5%). Histopathologic analysis showed that no patient had blood vessel invasion, 5 (35.7%) had lymphatic invasion, and 4 (28.6%) had perineural invasion. Four patients (28.4%) were classified as stage I and 10 (71.4%) were classified as stage II and III. From patients with RAS mutational analysis available (12), 9 (75%) presented tumor mutation. Although we present a limited sample, exact Fisher's test showed an association between lymphatic invasion and CTC number above the median (P= 0.03), and the presence of CTM was most frequent in this group of patients, although without statistical significance (P= 0.09). CTM absence was associated with pathologic T= 2 and 3 (P= 0.06), when compared to pathologic T= 4. Our next steps are to evaluate some proteins in CTCs that could confer an invasive phenotype, resistance to adjuvant treatment as well as verify the pattern of mutations in CTCs and CTMs. Moreover, this is the first study to show the efficacy of ISET method in detecting high rates of CTCs from stage I-III colon cancer patients. Citation Format: Emne Abdallah, Virgílio Silva, Bianca Flores, Alexcia Braun, Ana Urvanegia, Vanessa Alves, Marcello Fanelli, Samuel Aguiar, Ludmilla Chinen. Circulating tumor cell analysis in locally and advanced colon cancer: A pilot study [abstract]. In: Proceedings of the AACR International Conference held in cooperation with the Latin American Cooperative Oncology Group (LACOG) on Translational Cancer Medicine; May 4-6, 2017; São Paulo, Brazil. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(1_Suppl):Abstract nr B06.