Beta catenin immunostaining in MSS tumors.

<p><b>A.</b> Cross-section of a tumor from an MSS-Old patient shows only membrane staining. <b>B</b>. Cross-section of a tumor from a sporadic EOCRC (MSS–Young) patient shows strong cytoplasmic and nuclear staining with a loss of membrane staining, reflecting Wnt/beta catenin activation.</p

Sporadic Early-Onset Colorectal Cancer Is a Specific Sub-Type of Cancer: A Morphological, Molecular and Genetics Study

<div><p>Sporadic early onset colorectal carcinoma (EOCRC) which has by definition no identified hereditary predisposition is a growing problem that remains poorly understood. Molecular analysis could improve identification of distinct sub-types of colorectal cancers (CRC) with therapeutic implications and thus can help establish that sporadic EOCRC is a distinct entity. From 954 patients resected for CRC at our institution, 98 patients were selected. Patients aged 45–60 years were excluded to help define “young” and “old” groups. Thirty-nine cases of sporadic EOCRC (patients≤45 years with microsatellite stable tumors) were compared to both microsatellite stable tumors from older patients (36 cases, patients>60 years) and to groups of patients with microsatellite instability. Each group was tested for <i>TP53</i>, <i>KRAS</i>, <i>BRAF</i>, <i>PIK3CA</i> mutations and the presence of a methylator phenotype. Gene expression profiles were also used for pathway analysis. Compared to microsatellite stable CRC from old patients, sporadic EOCRC were characterized by distal location, frequent synchronous metastases and infrequent synchronous adenomas but did not have specific morphological characteristics. A familial history of CRC was more common in sporadic EOCRC patients despite a lack of identified hereditary conditions (p = 0.013). Genetic studies also showed the absence of <i>BRAF</i> mutations (p = 0.022) and the methylator phenotype (p = 0.005) in sporadic EOCRC compared to older patients. Gene expression analysis implicated key pathways such as Wnt/beta catenin, MAP Kinase, growth factor signaling (EGFR, HGF, PDGF) and the TNFR1 pathway in sporadic EOCRC. Wnt/beta catenin signaling activation was confirmed by aberrant nuclear beta catenin immunostaining (p = 0.01). This study strongly suggests that sporadic EOCRC is a distinct clinico-molecular entity presenting as a distal and aggressive disease associated with chromosome instability. Furthermore, several signaling pathways including the TNFR1 pathway have been identified as potential biomarkers for both the diagnosis and treatment of this disease.</p></div

Prognostic impact of positive baseline ctDNA.

<p>(A) PFS and (B) OS in patients with positive and negative ctDNA (<i>n</i> = 105).</p

Study design.

<p>(A) Flowchart of the study population. (B) Time point of ctDNA follow-up. *Includes ALK fusion (<i>n</i> = 3) and ROS1 fusion (<i>n</i> = 1). **PIK3CA p.H1047L. ^†TP53 p.Gly244Cys. ^$KRAS p.G12V, TP53 p.C135Y, and TP53 p.R248W. No mutations were found for <i>AKT1</i>, <i>ERBB2</i>, <i>FBXW7</i>, <i>FGFR2</i>, <i>MET</i>, or <i>NOTCH1</i>.</p

Clinico-pathological features of each group showing significant differences among the 79 variables studied.

<p>Data are expressed as absolute number and relative percentage. SD: standard deviation, M/F: male/female, UICC: Union for International Cancer Control (2002 classification), CRC: colorectal cancer. *: One case with liver and ovary metastases, 6 cases with liver and lung metastases, one case with liver and brain metastasis and one case with ovary and peritoneum metastasis. **: Two cases presented with liver and peritoneum metastases.</p

Plasma characteristics.

<p>Plasma characteristics.</p

Consort diagram.

<p>Consort diagram depicting the selection of patients from a single institution, on the basis of available frozen tissue and after applying exclusion criteria. Four groups were defined by taking into account age and MMR status. The study was designed to allow the comparison of MSS early-onset CRC with other well-defined groups of CRC. FAP: Familial Adenomatous Polyposis. IBD: Inflammatory Bowel Disease. MMR status: Mismatch Repair status. MSS: Microsatellite stable. MSI: Microsatellite unstable.</p

Unsupervised analysis of expression profiles of the four patient groups.

<p>Unsupervised classification of expression profiles: dendrogram of the closest clustering to the consensus partition for k = 5. Legend: io, MSI/Old; iy, MSI/Young; so, MSS/Old; sy, MSS/Young; d, deficient MMR; p, proficient MMR; R, right colon; L, left colon; Re, rectum; M, mutated; W, wild-type.</p

Clinical characteristics associated with ctDNA concentration.

<p>Correlation between T0 ctDNA concentration tertiles and (A) tumor burden defined by the sum of the RECIST target lesions (Mann-Whitney test) and (B) presence of liver metastasis (Fisher’s exact test). (C) Correlation between positive ctDNA at baseline and Ki67 proliferative index expressed as a % of positive cells in a subset of tumors with available tissue (<i>n</i> = 19, Mann-Whitney test). *<i>p</i> < 0.05, **<i>p</i> < 0.005, ***<i>p</i> < 0.001.</p

Summary of baseline patient and tumor characteristics.

<p>Summary of baseline patient and tumor characteristics.</p