Luis Vicioso

Breast cancer (BC) is the most prevalent cancer in women. While usually detected when localized, invasive procedures are still required for diagnosis. Herein, we developed a novel ultrasensitive pipeline to detect circulating tumor DNA (ctDNA) in a series of 75 plasma samples from localized BC patients prior to any medical intervention. We first performed a tumor-informed analysis to correlate the mutations found in tumor tissue and plasma. Disregarding the tumor data next, we developed an approach to detect tumor mutations in plasma. We observed a mutation concordance between the tumor and plasma of 29.50% with a sensitivity down to 0.03% in mutant variant allele frequency (VAF). We detected mutations in 33.78% of the samples, identifying eight patients with plasma-only mutations. Altogether, we determined a specificity of 86.36% and a positive predictive value of 88.46% for BC detection. We demonstrated an association between higher ctDNA median VAF and higher tumor grade, multiple plasma mutations with a likelihood of relapse and more frequent TP53 plasma mutations in hormone receptor-negative tumors. Overall, we have developed a unique ultra-sensitive sequencing workflow with a technology not previously employed in early BC, paving the way for its application in BC screening.

Circulating tumor DNA (ctDNA) has emerged as a non-invasive “liquid biopsy” for early breast cancer diagnosis. We evaluated the suitability of ctDNA analysis in the diagnosis of early breast cancer after mammography findings, comparing PIK3CA and TP53 mutations between tumor biopsies and pre-biopsy circulating DNA. Matched plasma and frozen fresh tissue biopsies from patients with Breast Imaging-Reporting and Data System (BIRADS) 4c/5 mammography findings and subsequent diagnosis of primary breast cancer were analyzed using NGS TruSeq Custom Amplicon Low Input Panel (Illumina) and plasma SafeSEQ (Sysmex Inostics). The same plasma and tumor mutations were observed in eight of 29 patients (27.6%) with four in TP53 and five in PIK3CA mutations. Sequencing analysis also revealed four additional ctDNA mutations (three in TP53 and one in PIK3CA) previously not identified in three patients tissue biopsy. One of these patients had mutations in both genes. Age, tumor grade and size, immunohistochemical (IHC) subtype, BIRADS category, and lymph node positivity were significantly associated with the detectability of these blood tumor-derived mutations. In conclusion, ctDNA analysis could be used in early breast cancer diagnosis, providing critical clinical information to improve patient diagnosis.

1585 Background: Male breast cancer (MBC) is a rare disease that is still poorly understood. It is mainly classified by immunohistochemistry (IHQ) as a luminal disease. In this study, we use for the first time the PAM50 signature to unravel the molecular genetic heterogeneity in MBC. Methods: We collected surgical specimens of invasive MBC from four different Spanish pathology laboratories. IHQ staining for estrogen receptor (ER), progesterone receptor (PR), androgen receptor (AR), human epidermal growth factor receptor 2 (HER2), cytokeratin 5/6 (CK5/6), epidermal growth factor receptor (EGFR) and Ki-67 was performed on tissue microarrays composed of 3 cores sized 0.6 mm per case by standard methods. Breast cancer molecular subtypes were classified according to Cheang et al. (2009). Gene-expression profiling was performed on a research-use-only (RUO) nCounter Analysis System using the RUO PAM50 assay analyzed with the Prosigna algorithm. We explored the association of IHQ and PAM50 subtypes using Fisher’s exact test. Results: From the 78 selected patients, 59 (76%) had enough tumor tissue to be classified by both IHQ and PAM50 approaches. The characteristics of our cohort are the following: mean age 63, tumor-size > 2cm 54%, grade 1 46%, positive lymph nodes 44%, adjuvant chemotherapy (CHT) 51%, hormonotherapy (HT) 80%, CHT+HT 41%. By IHQ these samples are mainly RE, RP and RA positive (97%, 86%, and 90% respectively); HER2, CK5/6 and EGFR negative (100%, 97% and 80%) and with a balanced Ki67 expression (Ki67 > 14 56%). When subtyping by IHQ and PAM50, the majority of samples are luminal B (54 and 63%, respectively) followed by luminal A (43% and 32%). Only 3% by IHQ and 5% by PAM50 are non-luminal (1 basal-like and 1 non-basal triple negative by IHQ and 3 Her2-enriched by PAM50). We found a strong association between both IHQ and PAM50 classifications (p-value = 0.007). Conclusions: In contrast with female breast cancer in which a third of the cases are non-luminal, our findings suggest that MBC is mainly a genomic luminal disease. More research is needed to identify the reason for the scarcity of non-luminal subtypes in MBC and the predominance of the luminal B subtype.

MicroRNAs (miRNAs) are involved in numerous biological and pathological processes including colorectal cancer (CRC). The aim of our study was to evaluate the ability of miRNA expression patterns to predict chemotherapy response in a cohort of 78 patients with metastatic CRC (mCRC). We examined expression levels of 667 miRNAs in the training cohort and evaluated their potential association with relevant clinical endpoints. We identified a miRNA profile that was analysed by RT-qPCR in an independent cohort. For a set of selected miRNAs, bioinformatic target predictions and pathway analysis were also performed. Eight miRNAs (let-7 g*, miR-107, miR-299-5p, miR-337-5p, miR-370, miR-505*, miR-889 and miR-99a-3p) were significant predictors of response to chemotherapy in the training cohort. In addition, overexpression of miR-107, miR-337-5p and miR-99a-3p, and underexpression of miR-889, were also significantly associated with improved progression-free and/or overall survival. MicroRNA-107 and miR-99a-3p were further validated in an independent cohort as predictive markers for chemotherapy response. In addition, an inverse correlation was confirmed in our study population between miR-107 levels and mRNA expression of several potential target genes (CCND1, DICER1, DROSHA and NFKB1). MiR-107 and miR-99a-3p were validated as predictors of response to standard fluoropyrimidine-based chemotherapy in patients with mCRC.

Introduction: Recurrence risk in breast cancer varies throughout the follow-up time. We examined if these changes are related to the level of expression of the proliferation pathway and intrinsic subtypes. Methods: Expression of estrogen and progesterone receptor, Ki-67, human epidermal growth factor receptor 2 (HER2), epidermal growth factor receptor (EGFR) and cytokeratin 5/6 (CK 5/6) was performed on tissue-microarrays constructed from a large and uniformly managed series of early breast cancer patients (N = 1,249). Subtype definitions by four biomarkers were as follows: luminal A (ER + and/or PR+, HER2-, Ki-67 <14), luminal B (ER + and/or PR+, HER2-, Ki-67 ≥14), HER2-enriched (any ER, any PR, HER2+, any Ki-67), triple-negative (ER-, PR-, HER2-, any Ki-67). Subtype definitions by six biomarkers were as follows: luminal A (ER + and/or PR+, HER2-, Ki-67 <14, any CK 5/6, any EGFR), luminal B (ER + and/or PR+, HER2-, Ki-67 ≥14, any CK 5/6, any EGFR), HER2-enriched (ER-, PR-, HER2+, any Ki-67, any CK 5/6, any EGFR), Luminal-HER2 (ER + and/or PR+, HER2+, any Ki-67, any CK 5/6, any EGFR), Basal-like (ER-, PR-, HER2-, any Ki-67, CK5/6+ and/or EGFR+), triple-negative nonbasal (ER-, PR-, HER2-, any Ki-67, CK 5/6-, EGFR-). Each four- or six-marker defined intrinsic subtype was divided in two groups, with Ki-67 <14% or with Ki-67 ≥14%. Recurrence hazard rate function was determined for each intrinsic subtype as a whole and according to Ki-67 value. Results: Luminal A displayed a slow risk increase, reaching its maximum after three years and then remained steady. Luminal B presented most of its relapses during the first five years. HER2-enriched tumors show a peak of recurrence nearly twenty months post-surgery, with a greater risk in Ki-67 ≥14%. However a second peak occurred at 72 months but the risk magnitude was greater in Ki-67 <14%. Triple negative tumors with low proliferation rate display a smooth risk curve, but with Ki-67 ≥14% show sharp peak at nearly 18 months. Conclusions: Each intrinsic subtype has a particular pattern of relapses over time which change depending on the level of activation of the proliferation pathway assessed by Ki-67. These findings could have clinical implications both on adjuvant treatment trial design and on the recommendations concerning the surveillance of patients.

Patients treated with tamoxifen often experience vaginal bleeding, generally because of benign endometrial lesions or, less often, because of endometrial carcinoma. A rare cause of vaginal bleeding in these patients is breast carcinoma metastasis in an endometrial polyp. We describe a 67-yr-old patient with metastasis of lobular breast carcinoma in an endometrial polyp and papillary serous endometrial carcinoma, both diagnosed simultaneously in a uterine curettage. The coexistence of the 2 cancers was confirmed by pathologic study of the hysterectomy specimen. To our knowledge, this is the first reported case of the synchronous presence of the 2 neoplastic diseases. Endometrial biopsies performed for endometrial disorders in patients who have breast cancer and have received tamoxifen should be studied carefully to avoid underdiagnosis.

The dissemination of tumour cells to the lymph nodes is a complex process involving the formation of new lymph vessels, or lymphangiogenesis, produced by the tumour itself. The main growth factor involved in lymphangiogenesis is vascular endothelial growth factor C (VEGF-C), which is secreted by several different malignant tumours, including melanoma. Not only has VEGF-C expression been found in tumour cells, it has also been detected in tumour stromal cells like macrophages and fibroblasts. This study aimed to determine whether the expression of VEGF-C in tumour and stromal cells in cutaneous melanoma determines lymphangiogenesis and neoplastic dissemination to lymph nodes. We examined cases from 50 patients with melanoma who underwent selective biopsy of the sentinel lymph node. Immunohistochemical study was done with D2-40 to label lymph vessels, and the expression of VEGF-C was evaluated in tumour and stromal cells. Lymph vessel density was greater in sentinel lymph node-positive than in sentinel lymph node-negative cases, though the difference was not significant (P = 0.075). A significant correlation was seen between lymph vessel density and tumour thickness and the presence of ulceration. The main finding was that the expression of VEGF-C in fibroblasts was highly associated with the presence of metastasis in the sentinel node and with the Clark level. However, VEGF-C expression showed no relation in either tumour cells or macrophages with node status or other prognostic factors, such as the Breslow index or Clark level. Our results highlight the relevance of the stroma in tumour progression in cutaneous melanoma and its role in the spread to lymph nodes.

Mutational analysis of the KRAS gene has recently been established as a complementary in vitro diagnostic tool for the identification of patients with colorectal cancer who will not benefit from anti-epidermal growth factor receptor (EGFR) therapies. Assessment of the mutation status of KRAS might also be of potential relevance in other EGFR-overexpressing tumors, such as those occurring in breast cancer. Although KRAS is mutated in only a minor fraction of breast tumors (5%), about 60% of the basal-like subtype express EGFR and, therefore could be targeted by EGFR inhibitors. We aimed to study the mutation frequency of KRAS in that subtype of breast tumors to provide a molecular basis for the evaluation of anti-EGFR therapies.