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INTRODUCTION: Molecular pathological epidemiology (MPE) is an integrative transdisciplinary area examining the relationships between various exposures and pathogenic signatures of diseases. In line with the accelerating advancements in MPE, social science and its health-related interdisciplinary areas have also developed rapidly. Accumulating evidence indicates the pathological role of social-demographic factors. We therefore initially proposed social MPE in 2015, which aims to elucidate etiological roles of social-demographic factors and address health inequalities globally. With the ubiquity of molecular diagnosis, there are ample opportunities for researchers to utilize and develop the social MPE framework. AREAS COVERED: Molecular subtypes of breast cancer have been investigated rigorously for understanding its etiologies rooted from social factors. Emerging evidence indicates pathogenic heterogeneity of neurological disorders such as Alzheimers disease. Presenting specific patterns of social-demographic factors across different molecular subtypes should be promising for advancing the screening, prevention, and treatment strategies of those heterogeneous diseases. This article rigorously reviewed literatures investigating differences of race/ethnicity and socioeconomic status across molecular subtypes of breast cancer and Alzheimers disease to date. EXPERT OPINION: With advancements of the multi-omics technologies, we foresee a blooming of social MPE studies, which can address health disparities, advance personalized molecular medicine, and enhance public health.

Background: Growing evidence supports the importance of characterizing the organizational patterns of various cellular constituents in the tumor microenvironment in precision oncology. Most existing data on immune cell infiltrates in tumors, which are based on immune cell counts or nearest neighbor-type analyses, have failed to fully capture the cellular organization and heterogeneity. Methods: We introduce a computational algorithm, termed Tumor-Immune Partitioning and Clustering (TIPC), that jointly measures immune cell partitioning between tumor epithelial and stromal areas and immune cell clustering versus dispersion. As proof-of-principle, we applied TIPC to a prospective cohort incident tumor biobank containing 931 colorectal carcinoma cases. TIPC identified tumor subtypes with unique spatial patterns between tumor cells and T lymphocytes linked to certain molecular pathologic and prognostic features. T lymphocyte identification and phenotyping were achieved using multiplexed (multispectral) immunofluorescence. In a separate hepatocellular carcinoma cohort, we replaced the stromal component with specific immune cell types—CXCR3+CD68+ or CD8+—to profile their spatial relationships with CXCL9+CD68+ cells. Results: Six unsupervised TIPC subtypes based on T lymphocyte distribution patterns were identified, comprising two cold and four hot subtypes. Three of the four hot subtypes were associated with significantly longer colorectal cancer (CRC)-specific survival compared to a reference cold subtype. Our analysis showed that variations in T-cell densities among the TIPC subtypes did not strictly correlate with prognostic benefits, underscoring the prognostic significance of immune cell spatial patterns. Additionally, TIPC revealed two spatially distinct and cell density-specific subtypes among microsatellite instability-high colorectal cancers, indicating its potential to upgrade tumor subtyping. TIPC was also applied to additional immune cell types, eosinophils and neutrophils, identified using morphology and supervised machine learning; here two tumor subtypes with similarly low densities, namely 'cold, tumor-rich' and 'cold, stroma-rich', exhibited differential prognostic associations. Lastly, we validated our methods and results using The Cancer Genome Atlas colon and rectal adenocarcinoma data (n = 570). Moreover, applying TIPC to hepatocellular carcinoma cases (n = 27) highlighted critical cell interactions like CXCL9-CXCR3 and CXCL9-CD8. Conclusions: Unsupervised discoveries of microgeometric tissue organizational patterns and novel tumor subtypes using the TIPC algorithm can deepen our understanding of the tumor immune microenvironment and likely inform precision cancer immunotherapy. Author summary: We have developed a computational tool called the Tumor-Immune Partitioning and Clustering (TIPC) algorithm, designed to reveal the intricate organization of immune cells within the tumor microenvironment. Traditionally, studies have mainly focused on counting these cells or examining their proximity to one another. Those approaches often underestimate the complex roles of immune cells in tumors. With TIPC, we have uncovered distinct patterns in the arrangement of immune cells across different tumor regions. This advancement has enabled us to identify tumor subtypes that were previously undetectable with existing methods. Our new method can determine which tumors are likely to have longer survival rates or respond better to immunotherapy, based on the layout of immune cells rather than merely their numbers. This breakthrough has significant implications for cancer research, highlighting the importance of understanding the spatial patterns of immune cells. Such knowledge is crucial for selecting appropriate patients for specific treatments and for assessing the potential effectiveness of immunotherapy. By tailoring treatment plans to the unique cellular landscapes of each tumor, we can potentially improve outcomes and provide more personalized and effective cancer care. [ABSTRACT FROM AUTHOR]

Background: Microsatellite instability-high (MSI-high) tumors comprise ~15% of sporadic colorectal cancers (CRC) and are associated with elevated T cell infiltration. However, the universality of this response across T cell subtypes with distinct functions is unknown. Methods: Including 1,236 CRC tumors from three observational studies, we conducted in-situ T cell profiling using a customized 9-plex (CD3, CD4, CD8, CD45RA, CD45RO, FOXP3, KRT, MKI67, and DAPI) multispectral immunofluorescence assay. MSI status was assessed through polymerase chain reaction or immunohistochemical assays. We used multivariable ordinal logistic regression to estimate odds ratios (OR per increasing quantile) and 95% confidence intervals (CIs) for the association of MSI status with quantiles of T cell densities in either tumor epithelial or stromal tissue areas. Results: Compared to microsatellite instability low or microsatellite stable (MSI-low/MSS) tumors, MSI-high status was associated with higher density for the majority of immune subsets (twelve out of eighteen) in both epithelial and stromal tissue areas. The strongest associations were for CD3+CD8+ T cells in epithelial areas [OR (95% CI) for naive, memory, and regulatory subsets = 3.49 (2.57, 4.75); 2.82 (2.10, 3.78); 3.04 (2.24, 4.13), respectively]. Conversely, stromal area CD3+CD4+ memory T cells were inversely associated [OR (95% CI) = 0.68 (0.51, 0.91)]. Discussion: MSI-high status was strongly associated with higher densities of most T cell subsets in both epithelial and stromal tissue areas. Our investigation supports efforts to identify patients who may be more likely to respond to current immunotherapy treatments. Significance: This study helps us better understand how a clinically relevant tumor phenotype, microsatellite instability status, is related to different functioning T cell densities in colorectal tumors, which may impact future immunotherapy strategies. [ABSTRACT FROM AUTHOR]

It remains unclear if pre‐diagnostic factors influence the developmental pathways of colorectal cancer (CRC) that could enhance tumor aggressiveness. This study used prospective data from 205,489 cancer‐free US health professionals to investigate the associations of 31 known or putative risk factors with the risk of aggressive CRC. Tumor aggressiveness was characterized by three endpoints: aggressive CRC (cancer that causes death within 5 years of diagnosis), fatal CRC, and tumor stage at diagnosis. The data augmentation method was used to assess the difference in the associations between risk factors and endpoints. We documented 3201 CRC cases, of which 899 were aggressive. The protective associations of undergoing lower endoscopy (hazard ratios [HR] 0.43, 95% confidence interval (CI) 0.37, 0.49 for aggressive versus HR 0.61, 95% CI 0.56, 0.67 for non‐aggressive) and regular use of aspirin (HR 0.70, 95% CI 0.61, 0.81 versus HR 0.84, 95% CI 0.77, 0.92) were stronger for aggressive than non‐aggressive CRC (pHeterogeneity <0.05). Lower intake of whole grains or cereal fiber and greater dietary inflammatory potential were associated with a higher risk of aggressive but not non‐aggressive CRC. The remaining risk factors showed comparable associations with aggressive CRC and non‐aggressive CRC. Aggressive cases were more likely to have KRAS‐mutated tumors but less likely to have distal or MSI‐high tumors (p <.007). Similar results were observed for fatal CRC and advanced tumor stages at diagnosis. These findings provide initial evidence for the role of pre‐diagnostic risk factors in the pathogenesis of aggressive CRC and suggest research priorities for preventive interventions. [ABSTRACT FROM AUTHOR]

Evidence indicates that combinations of anti‐EGFR antibodies and KRAS p.G12C (c.34G>T) inhibitors can be an effective treatment strategy for advanced colorectal cancer. We hypothesized that KRAS c.34G>T (p.G12C)‐mutated colorectal carcinoma might be a distinct tumor subtype. We utilized a prospective cohort incident tumor biobank (including 1347 colorectal carcinomas) and detected KRAS c.34G>T (p.G12C) mutation in 43 cases (3.2%) and other KRAS mutations (in codon 12, 13, 61, or 146) in 467 cases (35%). The CpG island methylator phenotype (CIMP)‐low prevalence was similarly higher in KRAS c.34G>T mutants (52%) and other KRAS mutants (49%) than in KRAS‐wild‐type tumors (31%). KRAS c.34G>T mutants showed higher CIMP‐high prevalence (14%) and lower CIMP‐negative prevalence (33%) compared with other KRAS mutants (6% and 45%, respectively; p = 0.0036). Similar to other KRAS mutants, KRAS c.34G>T‐mutated tumors were associated with cecal location, non‐microsatellite instability (MSI)‐high status, BRAF wild type, and PIK3CA mutation when compared with KRAS‐wild‐type tumors. Compared with BRAF‐mutated tumors, KRAS c.34G>T mutants showed more frequent LINE‐1 hypomethylation, a biomarker for early‐onset colorectal carcinoma. KRAS c.34G>T mutants were not associated with other features, including the tumor tissue abundance of Fusobacterium nucleatum (F. animalis), pks+Escherichia coli, Bifidobacterium, or (enterotoxigenic) Bacteroides fragilis. Among 1122 BRAF‐wild‐type colorectal carcinomas, compared with KRAS‐wild‐type tumors, multivariable‐adjusted colorectal cancer‐specific mortality hazard ratios (95% confidence interval) were 1.82 (1.05–3.17) in KRAS c.34G>T (p.G12C)‐mutated tumors (p = 0.035) and 1.57 (1.22–2.02) in other KRAS‐mutated tumors (p = 0.0004). Our study provides novel evidence for clinical and tumor characteristics of KRAS c.34G>T (p.G12C)‐mutated colorectal carcinoma. [ABSTRACT FROM AUTHOR]

Background We examined whether the association between alcohol consumption and colorectal cancer (CRC) incidence was stronger for tumors with higher contributions of defective mismatch repair (dMMR)–related tumor mutational signatures. Methods We used data from 227 916 men and women who participated in the Nurses' Health Study (1980-2016), the Nurses' Health Study II (1991-2017), and the Health Professionals Follow-Up Study (1986-2016). Dietary data were collected every 4 years through validated food frequency questionnaires. Relative contributions of 2 defective mismatch repair–related tumor mutational signatures with single-based substitutions (c-dMMRa/SBS15 and c-dMMRb/SBS26) were quantified using whole-exome sequencing data in a subset of incident CRC patients. Duplication-method Cox proportional hazards regression models were used to assess the association between alcohol consumption and the risk of CRC subtypes according to different contributions of the tumor mutational signatures. All statistical tests were 2-sided. Results We documented 825 incident CRC patients with available tumor mutational signature data over 26 to 36 years of follow-up. The association between alcohol consumption and CRC incidence was stronger for tumors with higher contributions of c-dMMRb/SBS26 (P trend = .02 for heterogeneity) compared with tumors with lower contributions of this tumor mutational signature. Compared with nondrinkers, drinkers who imbibed 15 g/d or more of alcohol had a high risk of c-dMMRb/SBS26-high CRC (multivariable-adjusted hazard ratio = 2.43, 95% confidence interval = 1.55 to 3.82) but not c-dMMRb/SBS26-low CRC (multivariable-adjusted hazard ratio = 0.86, 95% confidence interval = 0.57 to 1.28) or c-dMMRb/SBS26-moderate CRC (multivariable-adjusted hazard ratio = 1.14, 95% confidence interval = 0.76 to 1.71). No significant differential associations were observed for c-dMMRa/SBS15 (P trend = .41 for heterogeneity). Conclusions High alcohol consumption was associated with an increased incidence of CRC containing higher contributions of c-dMMRb/SBS26, suggesting that alcohol consumption may be involved in colorectal carcinogenesis through the DNA mismatch repair pathway. [ABSTRACT FROM AUTHOR]

A multi-disciplinary symposium on early-age onset cancer (EAOC) was held in October 2023 to explore challenges experienced by this rapidly growing population. A major outcome of the symposium was recognition of the remarkable similarities of EAOC patients' journeys across cancer sites. Prevention and early detection of cancer are hindered by a lack of awareness among patients and family doctors that cancer can and does occur in younger persons. Distinct characteristics of the disease—such as a later stage at diagnosis and more aggressive tumor biology—require more potent treatments, which result in profound physical and psychosocial consequences that are unique to this age group. EAOC patient empowerment emerged as another key theme of the symposium. The development of a greater number of specialized clinics was called for, and patient support groups were recognized for the vital role they play in empowering patients and their families. Leading-edge medical advancements hold tremendous hope across the spectrum of EAOC care. New technologies based on genomic profiling, immunotherapy and microbiome alteration contribute to the development of highly effective, personalized approaches to treatment. All symposium participants expressed their commitment to speak with one resounding voice to advocate for equitable access to leading care practices for EAOC patients; thus, a fourth symposium is planned for November 2024. [ABSTRACT FROM AUTHOR]