Stem and immune cells in colorectal primary tumour: Number and function of subsets may diagnose metastasis

An important percentage of colorectal cancer (CRC) patients will develop metastasis, mainly in the liver, even after a successful curative resection. This leads to a very high mortality rate if metastasis is not detected early on. Disseminated cancer cells develop from metastatic stem cells (MetSCs). Recent knowledge has accumulated about these cells particularly in CRC, so they may now be tracked from the removed primary tumour. This approach could be especially important in prognosis of metastasis because it is becoming clear that metastasis does not particularly rely on testable driver mutations. Among the many traits supporting an epigenetic amplification of cell survival and self-renewal mechanisms of MetSCs, the role of many immune cell populations present in tumour tissues is becoming clear. The amount of tumour-infiltrating lymphocytes (T, B and natural killer cells), dendritic cells and some regulatory populations have already shown prognostic value or to be correlated with disease-free survival time, mainly in immunohistochemistry studies of unique cell populations. Parallel analyses of these immune cell populations together with MetSCs in the primary tumour of patients, with later follow-up data of the patients, will define the usefulness of specific combinations of both immune and MetSCs cell populations. It is expected that these combinations, together to different biomarkers in the form of an immune score, may predict future tumour recurrences, metastases and/or mortality in CRC. It will also support the future design of improved immunotherapeutic approaches against metastasis.     

Microbiome and colorectal cancer: Unraveling host-microbiota interactions in colitis-associated colorectal cancer development

Dysbiosis of gut microbiota occurs in many human chronic immune-mediated diseases, such as inflammatory bowel disease (IBD) and colitis-associated colorectal cancer (CAC). Reciprocally, uncontrolled immune responses, that may or may not be induced by dysbiosis, are central to the development of IBD and CAC. There has been a surge of interest in investigating the relationship between microbiota, inflammation and CAC. In this review, we discuss recent findings related to gut microbiota and chronic immune-mediated diseases, such as IBD and CAC. Moreover, the molecular mechanisms underlying the roles of chronic inflammation in CAC are examined. Finally, we discuss the development of novel microbiota-based therapeutics for IBD and colorectal cancer.     

Comparison of survival outcomes between primary and secondary muscle-invasive bladder cancer: An updated meta-analysis

Objective: Studies have showed that different follow-up starting points might potentially impact the comparison between primary (PMIBC) and secondary muscle-invasive bladder cancer (SMIBC), but the only previous meta-analysis did not differentiate the follow-up starting points of included studies. With more trials published, we aim to update the meta-analysis comparing PMIBC and SMIBC.Methods: PubMed, Embase, Cochrane Library and ClinicalTrial.gov. systematically searched. Literatures comparing the survival outcomes of PMIBC and SMIBC were selected. Outcomes of cancer-specific mortality (CSM), overall mortality (OM) and recurrence-free survival (RFS) were pooled and grouped based on the starting point of follow-up (after initial diagnosis or radical cystectomy (RC)). Newcastle-Ottawa Scale (NOS) and funnel plot were employed to assess the study quality and publication bias, respectively.Results: A total of 17 high-quality studies were selected, with 5558 patients aged from 59.8 to 72.7 (mean value) involved. The male-to-female ratio was roughly 4:1 (4390/1124). SMIBC had lower risk of CSM after initial diagnosis (HR 0.81, 95%CI 0.67-0.98, P=0.03, I²=70%), but higher risk of CSM after RC (HR 1.45, 95%CI 1.27-1.65, P<0.00001, I²=64%). In terms of OM and recurrence, outcomes were pooled only after RC, which both turned out to be higher for SMIBC (OM: HR 1.50, 95%CI 1.30-1.73, P<0.00001, I²=0%; Recurrence: HR 1.66, 95%CI 1.36-2.02, P<0.00001, I²=48%). No obvious publication bias was observed from funnel plot.Conclusion: The current study suggested SMIBC had higher risk of CSM, OM and recurrence after RC, but lower risk of CSM after initial diagnosis.     

Methylation-dependent silencing of CST6 in primary human breast tumors and metastatic lesions

CST6 is a breast tumor suppressor gene that is expressed in normal breast epithelium, but is epigenetically silenced as a consequence of promoter hypermethylation in metastatic breast cancer cell lines. In the current study, we investigated the expression and methylation status of CST6 in primary breast tumors and lymph node metastases. 25/45 (56%) primary tumors and 17/20 (85%) lymph node metastases expressed significantly lower levels of cystatin M compared to normal breast tissue. Bisulfite sequencing demonstrated CST6 promoter hypermethylation in 11/23 (48%) neoplastic lesions analyzed, including 3/11 (27%) primary tumors and 8/12 (67%) lymph node metastases. In most cases (12/23, 52%), the expression of cystatin M directly reflected CST6 promoter methylation status. In remaining lesions (8/23, 35%) loss of cystatin M was not associated with CST6 promoter hypermethylation, indicating that other mechanisms can account for loss of CST6 expression. These results show that methylation-dependent silencing of CST6 occurs in a subset of primary breast cancers, but more frequently in metastatic lesions, possibly reflecting progression-related genomic events. To examine this possibility, primary breast tumors and matched lymph node metastases were analyzed. In 2/3 (67%) patients, primary tumors were positive for cystatin M and negative for CST6 promoter methylation, and matched metastatic lesions lacked cystatin M expression and CST6 was hypermethylated. This observation suggests that progression-related epigenetic alterations in CST6 gene expression can accompany metastatic spread from a primary tumor site. Overall, the results of the current investigation suggest that methylation-dependent epigenetic silencing of CST6 represents an important mechanism for loss of CST6 during breast tumorigenesis and/or progression to metastasis.     

结肠癌组织中Ski的表达及其与临床病理因素的关系

目的 研究Ski在结肠癌组织中的表达与临床病理因素的相关性.方法 采用免疫组化检测癌旁和结肠癌组织中Ski蛋白表达情况.结果 结肠癌组织中Ski蛋白表达阳性率[61.76％(21/34)]明显高于癌旁组织[38.24％(13/34)],差异具有统计学意义(P=0.02).Ski阳性表达与肿瘤的浸润深度(P=0.03)、有无淋巴结转移(P=0.005)和患者的预后有关(P=0.005),而与患者的性别、年龄、肿瘤分化程度无关(P＞0.05).结论 Ski在结肠癌组织中的表达明显增强,并且与肿瘤的浸润、转移和患者的预后有关.     

VEGF-C在晚期卵巢癌原发灶和转移灶中的表达比较

目的 研究血管内皮生长因子C（VEGV-C）在晚期卵巢癌原发灶和转移灶中的表达并进行比较,探讨其与晚期卵巢癌发生、发展及预后的关系。方法 应用SP免疫组织化学技术检测52例晚期卵巢癌原发灶以及相应的大网膜转移灶中VEGF-C的表达。结果 VEGF-C在52例卵巢上皮癌中原发灶的高表达率为21％（11／52）,其中透明细胞癌与黏液性癌相比有显著性差异（X^2=6．97,P〈0．01）;在转移灶的高表达阳性率为35％（18／52）,各种组织学类型之间无显著性差异（P〉0．01）。卵巢癌原发灶和转移灶之间VEGF-C表达无明显差异（P〉0．05）。结论 VEGF-C在晚期卵巢癌组织中表达增高,原发灶与转移灶之间无明显差异。     

Smoothelin and caldesmon are reliable markers for distinguishing muscularis propria from desmoplasia: a critical distinction for accurate staging colorectal adenocarcinoma

An accurate distinction between deep muscularis propria invasion versus subserosal invasion by colonic adenocarcinoma is essential for the accurate staging of cancer and subsequent optimal patient management. However, problems may arise in pathologic staging when extensive desmoplasia blurs the junction between deep muscularis propria and subserosal fibroadipose tissue. To address this issue, forty-three (43) cases of colonic adenocarcinoma resections from 2007-2009 at The Methodist Hospital in Houston, TX were reviewed. These cases were selected to address possible challenges in differentiating deep muscularis propria invasion from superficial subserosal invasion based on H&E staining alone. Immunohistochemical staining using smooth muscle actin (SMA), smoothelin, and caldesmon were performed on 51 cases: 8 cases of pT1 tumors (used mainly as control); 12 pT2 tumors; and 31 pT3 tumors. All 51 (100%) had diffuse, strong (3+) immunoreactivity for caldesmon and smoothelin in the muscularis propria with a granular cytoplasmic staining pattern. However, the desmoplastic areas of these tumors, composed of spindled fibroblasts and myofibroblasts, showed negative immunostaining for caldesmon and smoothelin (0/35). SMA strongly stained the muscularis propria and weakly (1+) or moderately (2+) stained the spindled fibroblasts in the desmoplastic areas (the latter presumably because of myofibroblastic differentiation). Compared to SMA, caldesmon and smoothelin are more specific stains that allow better delineation of the muscularis propria from the desmoplastic stromal reaction which provides a critical aide for proper staging of colonic adenocarcinoma and subsequent patient care.     

Chemokine expression is associated with the accumulation of tumour associated macrophages (TAMs) and progression in human colorectal cancer

Chemokines promote tumour progression by enhancing proliferation and modifying the immune response. The purpose of this study was to test the hypothesis that CCL2 monocyte chemotactic protein-1 (MCP-1) contributes to the progression of colorectal cancer by influencing the number and distribution of tumour associated macrophages (TAMs). Chemokine expression was assessed in human colorectal adenocarcinomas by ribonuclease protection assay (RPA). Colonic adenocarcinoma cell lines were used to assess chemokine production by enzyme linked immunosorbant assay (ELISA), and Boyden microchemotaxis assays were performed to determine cell line supernatant monocyte chemotactic activity. CCL2 production was assessed in paraffin embedded tumour samples by immunohistochemistry. Finally, the number of macrophages and their distribution was determined in the same colorectal adenocarcinomas and compared with CCL2 expression and tumour stage. Results showed that CCL2 produced by cell lines induced monocyte chemoattraction, the expression of this chemokine in solid cancers increased with tumour stage (P < 0.05) and immunohistochemistry localized production to tumour cells. Analysis of the macrophage infiltrate showed that the accumulation was significantly greater in tumours than controls (P < 0.005) and within tumours it was greatest in necrotic regions (median 44,600 per mm³). Macrophage accumulation increased with tumour stage and correlated with CCL2 expression (r _s = 0.8). CXCL8 interleukin 8 (IL-8), a potent angiogenic factor and growth factor, was expressed in all tumours and cell lines. It is concluded that CCL2 induces the accumulation of tumour promoting TAMs in human colorectal cancer and represents a therapeutic target to modify the macrophage response and direct immune mediated therapy.     

APRIL调节基质金属蛋白酶的表达对结直肠癌细胞转移侵袭能力的影响

目的 研究增殖诱导配体(a proliferation-inducing ligand,APRIL)对结直肠癌(colorectal cancer,CRC)细胞转移侵袭能力和基质金属蛋白酶(matrix metalloproteinases,MMPs)表达的影响,以进一步明确APRIL在CRC转移中的作用.方法 APRIL基因的小干扰RNA质粒载体(siRNAAPRIL)转染人CRC细胞SW480,APRIL重组蛋白(rhAPRIL)刺激CRC细胞HCT-116,Transwell小室转移及侵袭试验分析APRIL对CRC细胞转移及侵袭能力的影响;RT-PCR、ELISA检测MMPs的表达变化.结果 siRNA-APRIL转染的SW480细胞Transwell小室试验转移及侵袭细胞数显著减少(P＜0.05),rhAPRIL刺激的HCT-116细胞Transwell小室试验转移及侵袭细胞数显著增多(P＜0.05);MMP-2、MMP-9及TIMP-1 mRNA,分泌型的MMP-2、MMP-9蛋白表达在转染或刺激前后差别均有统计学意义(P＜0.05);MMP的抑制剂GM6001处理后,SW480对照组和rhAPRIL刺激后的HCT-116细胞Transwell小室侵袭细胞数显著减少(P＜0.05).结论 APRIL通过调节MMPs的表达促进结直肠癌的侵袭和转移,可为结直肠癌转移的干预及治疗提供新的靶点.     

CpG island methylation,response to combination chemotherapy,and patient survival in advanced microsatellite stable colorectal carcinoma

The CpG island methylator phenotype (CIMP) is a distinct epigenetic phenotype in colorectal carcinoma with concordant methylation in multiple promoter CpG islands. The relationship between CpG island methylation and clinical outcomes among colorectal cancer patients treated with chemotherapy has been a controversial subject. Utilizing real-time polymerase chain reaction (PCR; MethyLight technology), we quantified DNA methylation in 13 CpG island loci (CACNA1G, CDKN2A, CRABP1, IGF2, MLH1, NEUROG1, RUNX3, SOCS1, MINT1, MINT31, IGFBP3, MGMT, and WRN) in 30 metastatic microsatellite stable colorectal carcinomas in phase I/II clinical trials of combination chemotherapy (5-fluorouracil, irinotecan, leucovorin, and gefitinib). Tumor response was assessed by CT scans performed at baseline and every 6 weeks thereafter. Overall CIMP-high status (either ≥9/13 or ≥7/13 methylated markers; identifying 3 or 5 CIMP-high tumors, respectively) and methylation in CACNA1G, IGF2, MLH1, NEUROG1, RUNX3, MINT31, and WRN were associated with worse survival (all p < 0.01). Although not statistically significant, there was a trend toward resistance to chemotherapy among tumors with CpG island methylation. In conclusion, CpG island methylation may predict poor survival in metastatic microsatellite stable colorectal carcinoma treated with chemotherapy. Additional studies are necessary to examine the role of DNA methylation in treatment efficacy.     

Apoptosis and cell-cycle regulatory proteins in colorectal carcinoma: relationship to tumour stage and patient survival

The quantitative assessment of apoptotic index (AI) and mitotic index (MI) and the immunoreactivity of p53, bcl-2, p21, and mdm2 were examined in tumour and adjacent normal tissue samples from 30 patients with colonic and 22 with rectal adenocarcinoma. Individual features and combined profiles were correlated with clinicopathological parameters and patient survival data to assess their prognostic value. Increased AI was significantly associated with increased bcl-2 expression (p<0.008) and the immunoprofiles that included bcl-2, but not with MI, p53, p21 or mdm2. AI was significantly associated with increased Dukes' stage from A, B to C (p<0.02) but not D, while MI showed a significant association with all Dukes' stages (p<0.05). No significant association was found between either AI or MI and prognosis. p53, p21, mdm2, and bcl-2 positivity were detected in 65.4%, 53.8%, 65.4%, and 34.6% of cases, respectively. mdm2 was significantly associated with p53 (p<0.03) and p21 (p<0.04) expression and p53 immunoreactivity was more prevalent in rectal tumours (p<0.008). In univariate survival analysis, bcl-2 overexpression was associated with more favourable patient survival (p<0.03). Positive combined patterns p53+/p21+/bcl-2+ and p21+/mdm2+/bcl-2+ (p<0.005); p53+/bcl-2+, p21+/bcl-2+, and mdm2+/bcl-2+ (p<0.01); and p53+/p21+ (p<0.02) were also associated with favourable clinical outcome. In multivariate Cox survival analysis, bcl-2 (p<0.016) and Dukes' stage (p<0.0001) were the only significant independent prognostic indicators. In conclusion, bcl-2 immunoreactivity was associated with apoptosis and could be used in combination with Dukes' stage as a means of predicting prognosis in colorectal cancer.     

Comparison of losses of heterozygosity and replication errors in primary colorectal carcinomas and corresponding liver metastases

In order to investigate genetic alterations specific to liver metastases of colorectal carcinomas, losses of heterozygosity and replication errors have been compared in 15 cases of primary colorectal carcinoma and in the corresponding metastatic liver tumours. Fifteen microsatellite markers located on 13 different chromosomal arms were used in the study. The LOH patterns of the primary and the metastatic tumours were identical in eight cases and showed differences in seven cases. Areas of deletion predominantly or completely common to the colorectal and the metastatic tumour were detected on chromosomes 5q, 8p, 17p, 18q, and 22q. Preferential loss in metastatic tumours was observed on chromosomal arm 3p. Replication errors were found in four primary tumours and in three of the corresponding secondaries. A replication error phenotype specific to a metastasis was not observed. Copyright © 1999 John Wiley & Sons, Ltd.     

Surface phenotype and functions of tumor-infiltrating dendritic cells: CD8 expression by a cell subpopulation

Although the function and significance of tumor-infiltrating dendritic cells (TIDC) in the immune response to tumor have never been clearly demonstrated, their location suggests that they play a critical role in the presentation of tumor antigen to specific T cells. We studied the morphological and functional characteristics of interstitial dendritic cells (DC) located inside tumors obtained by injection of cancer cells into syngeneic rats. Single and double immunostaining of tumor sections revealed a dense network of cells which expressed class II major histocompatibility complex (MHC II) molecules. Cell morphology and surface markers were characteristic of DC populations in other tissues. These DC were in close contact with tumor cells and increased in number as the tumor grew larger. Unexpectedly, a subpopulation of morphologically characteristic TIDC expressed both CD8 and MHC II molecules. TIDC were purified from tumors by gradient centrifugation and immunobeads and characterized by morphology, ultrastructural study and surface markers studied by flow cytometry. TIDC were negative for the CD5 molecule (a pan T cell marker), and were not labeled with 3.2.3 monoclonal antibody (mAb) (an NK cell marker) or with Ki-M2R mAb (a macrophage marker). A subpopulation of TIDC expressed the CD8 molecule, confirming the in situ results. TIDC expressed high levels of class I and class II MHC molecules and the adhesion molecule ICAM-1. This expression is compatible with effective antigen presenting function. Purified TIDC triggered rapid and high levels of proliferation of tumor-immune T cells in vitro, demonstrating the potential of these cells to constitutively process and present tumor-associated antigens.     

Microvascular architecture of human epicolic and paracolic lymph nodes located in the vicinity of colon cancer: a SEM study of corrosion casts

The vascular systems of epicolic and paracolic lymph nodes located in the vicinity of colon tumors resected from three patients were investigated by corrosion casting and scanning electron microscopy. Large vessels entered the nodes either at one site, not always corresponding with the anatomical hilus, or at 2-4 sites located along their perimeters. In the cortical zone of most examined nodes, the location of lymphoid nodules was marked by rosette-like capillary arrays drained by peripheral arcuate venules. The paracortex and medulla showed a dense capillary network with areas of tortuous capillaries, sometimes forming glomerular arrays suggesting nonsprouting angiogenesis by capillary elongation. Venules were abundant, especially in the paracortex and medulla, but high endothelial venules showing characteristic imprints of bulging endothelial cells in the casts were very rarely observed. Focal angiogenesis, abundance of venules and scarcity of high endothelial venules could result from remodeling of blood vessels induced by the tumor.     

Immunohistochemical metallothionein expression in colorectal adenocarcinoma: correlation with tumour stage and patient survival

Metallothioneins (MTs), a set of ubiquitous low-molecular-weight proteins essential for the protection of cells against heavy metal ion toxicity, were demonstrated immunohistochemically using a monoclonal antibody (E9) against a conserved epitope of I and II isoforms in a series of 109 colorectal adenocarcinomas. In a semiquantitative analysis strong MT expression in the majority of tumour cells was observed in 34 (31%) cases, 24 (22%) tumours showed a focal MT positivity, and 51 (47%) almost completely lacked MT expression. These differences in MT expression were statistically significantly (P<0.05) associated with the tumour stage (Dukes classification) and the lymph node involvement at the time of operation (pN stages). However, in contrast to previous findings obtained on a variety of tumours, MT positivity was associated with a favourable clinical outcome in colonic carcinoma, which may indicate their different biological behaviour. Survival curves of cases with MT-positive and MT-negative status differed from each other in a univariate analysis (Mantel-Haenszel: 8.9, P<0.05) but lost significance when a multivariate analysis was carried out by means of the Cox proportional regression model with Dukes' stages as a stratification factor. It is concluded that immunohistochemically demonstrated MT expression is significantly associated with tumour stages but does not represent an independent prognostic variable in colorectal cancer. However, it may provide important information about some of the biological mechanisms underlying progression in colorectal cancer.     

不同类型中药制剂逆转结直肠癌T细胞免疫抑制及其靶分子的比较研究

目的比较研究不同类型抗瘤中药制剂对结直肠癌所致T细胞免疫抑制的影响,寻找能有效逆转结直肠癌T细胞免疫抑制的抗瘤中药制剂组方。方法分别制备三氧化二砷(As2O3)、川芎嗪(LHC)、黄芪(AMB)、氧化苦参碱(MOX)、猪苓多糖(PUPS)、青蒿琥酯(ART)等6种中药制剂作用后的小鼠结直肠癌Colon26细胞再培养上清;MTT法检测中药制剂作用后对Colon26所致T细胞转化抑制的影响,直接免疫荧光FCM法检测对IL-2Rα及CD3ε+ζ+表达抑制的影响;定量ELISA法测定上清中TGF-β1、VEGF、IL-4、IL-6、IL-10和PGE2含量;多元相关分析中药制剂逆转结直肠癌T细胞免疫抑制的相应靶分子。结果 AMB、PUPS及ART对T细胞转化抑制的下调程度较强(下调约50%),维持时间较长;ART对IL-2Rα表达抑制的下调作用最强(下调约50%),维持时间较长;AMB对CD3ε+ζ+表达抑制的下调作用最强,不但可完全消除表达抑制,还可进一步促进表达,维持时间亦较持久。对Colon26肿瘤细胞所致转化抑制及CD3ε+ζ+表达抑制的逆转,LHC的作用靶分子为TGF-β1和IL-10,其他5种中药制剂的靶分子均为TGF-β1。对IL-2Rα表达抑制的逆转,除AMB以外其他5种中药制剂的靶分子均为TGF-β1。结论通过阻碍肿瘤细胞分泌TGF-β1、IL-10等免疫抑制分子,以逆转肿瘤细胞产生的T细胞免疫抑制,应是中药制剂的新型抗瘤机制之一。     

Differential expression of microRNAs in colorectal cancer: Different patterns between isolated cancer gland and stromal cells

Although microRNAs (miRNAs) play an important role in invasive tumor lesions, which involve cancer tissues mixed with stromal tissues, the differences in miRNA expression between cancer and stromal cells remain unclear. We selected 13 miRNAs and examined their differential expression patterns in cancer gland cells and surrounding stromal cells isolated from 24 colorectal cancer (CRC) specimens using a crypt isolation method. Although six miRNAs were upregulated in gland cells, only three were upregulated in the corresponding stromal cells, in the cancer compared with non‐cancer specimens. Next, we examined the differences in miRNA expression between isolated cancer gland and stromal cells. Five miRNAs showed statistical differences in their cancer‐related differential expression patterns between isolated cancer gland and stromal cells. We then compared these miRNA expression patterns in isolated cancer gland and stromal cells with those in fresh intact tumor tissues, consisting of cancer nests and stromal tissue, obtained from the 24 CRCs. The expression patterns of three miRNAs in the intact cancer tissue samples did not correspond with those in the isolated components. Identification of the expression patterns of miRNAs in both the cancer gland and stromal cell components of the tumor microenvironment greatly contributes to evaluating epigenetic regulation in CRC.     

Frequency of apoptosis relates inversely to invasiveness and metastatic activity in human colorectal cancer

 The frequency of apoptosis was determined in 102 cases of human colorectal cancer. The results were correlated with the frequency of cell proliferation and with clinicopathological characteristics such as degree of differentiation, invasiveness and metastasis. As a marker of apoptosis, intranuclear DNA strand breaks were localized with in situ nick translation (ISNT). As a marker of proliferation, proliferating cell nuclear antigen (PCNA) was localized immunohistochemically. The numbers of nuclei positive with ISNT and for PCNA per 1,000 nuclei on tissue sections were obtained. The labelling indices were compared with clinicopathological characteristics for each tumour. The ISNT labelling index of well differentiated colon carcinomas was higher than that of poorly differentiated carcinomas. Among similarly differetiated cancers, ISNT L.I. of colon carcinomas classified as Dukes A was higher than Dukes B/C, and L.I. of carcinomas which did not metastasize to lymph node or liver was higher than that of carcinomas which metastasized. The PCNA labelling index did not correlate with any of the clinicopathological characteristics or with the ISNT labelling index. The data suggest that apoptosis indices severe as a marker of tumour progression. Received: 28 October 1996 / Accepted: 15 April 1997     

Using tumour pathology to identify people at high genetic risk of breast and colorectal cancers

Genes have been identified for which germline mutations are associated with high lifetime risks of breast, colorectal and other cancers. Identification of mutation carriers through genetic testing is important as it could help lower cancer incidence and mortality. The translation of genetic information into better health outcomes is expensive because of the costs of genetic counselling as well as laboratory testing. Approaches to triage for mutation screening of known genes which rely on cancer family history are not necessarily sensitive and specific or the most cost-effective. Recent population-based research has shown that the cancers and precancerous lesions arising in mutation carriers have specific molecular and morphological characteristics. People with colorectal cancer, especially those diagnosed at a young age, whose tumours exhibit microsatellite instability and some specific pathology and immunohistochemically-defined features are more likely to carry a germline mutation in one of four mismatch repair genes. Some morphological and immunohistochemically-defined features are associated with breast cancers arising in women who carry BRCA1 or BRCA2 germline mutations, especially if at a young age. Screening paradigms based on molecular and morphological features that predict mutation status, especially if focused on early-onset disease, have the potential to identify mutation carriers with greater sensitivity and specificity, and in a more cost-effective way, than those based on family history alone. Genetic testing results could help inform treatment if those affected are tested soon after diagnosis using pathology-led selection strategies to identify cases most likely to carry germline mutations. We propose how this new approach could be undertaken by having genetic testing and counselling prioritised to those with the greatest probability of carrying a germline mutation in these known cancer predisposition genes.