592 ATR-mediated CD47 and PD-L1 upregulation restricts radiotherapy-induced immune priming and abscopal responses in colorectal cancer

Background

Background: Radiotherapy of colorectal cancer (CRC) can prime adaptive immunity against tumor-associated antigen (TAA)-expressing CRC cells systemically; however, incidences of abscopal tumor remission are extremely rare. We sought to unravel the post-irradiation immune escape mechanisms in CRC.

Methods

Methods

Flow cytometry, gene knockdown, RNA and T cell receptor sequencing, and multiple murine syngeneic CRC models were used to interrogate mechanisms of CRC immune evasion following radiotherapy. Comparison of immunohistochemistry staining between pretreatment biopsy and post-irradiation surgical specimens was performed in rectal patients who underwent neoadjuvant radiotherapy with 5 Gy for 5 fractions.

Results

Results

We find that CRC cells utilize a common DNA repair signaling pathway — ATR/Chk1/STAT3 — to upregulate both CD47 and PD-L1 in response to radiotherapy, which through engagement of SIRPα and PD-1 suppresses the capacity of antigen-presenting cells (APCs) to phagocytose them thereby preventing TAA cross-presentation. This post-irradiation CD47 and PD-L1 upregulation can be observed in CRC cells treated with either photon or proton radiotherapy and across a wide variety of human solid tumor cells. Concordantly, rectal cancer patients who responded poorly (tumor regression grade 4–5, n = 10) to neoadjuvant radiotherapy exhibited significantly elevated post-irradiation CD47 levels (P = 0.005). In murine CRC models, the combination of radiotherapy, αSIRPα, and αPD-1 (RSP) profoundly enhances TAA uptake, activation of innate immune sensors, and TAA cross-priming across various antigen-presenting myeloid populations in the irradiated tumor microenvironment and facilitates TAA-presenting APC migration to secondary lymphoid organs. Furthermore, we observed robust production of TAA-specific CD8 T cells, functional activation of effector T cells, and increased tumor-infiltrating T cell clonality and clonal diversity in mice treated with RSP. Importantly, radiotherapy coupled with phagocytosis checkpoint blockade significantly improves complete response rates in both irradiated and abscopal tumors and prolongs survival in three distinct murine CRC models, including a cecal orthotopic model. In addition, αSIRPα exerts superior tumoricidal efficacy than αCD47 in combination with RT and αPD-1. We find RSP efficacy to be STING dependent as knockout animals lose most benefit of phagocytosis checkpoint blockade.

Conclusion

ATR-mediated CD47 and PD-L1 upregulation restrains radiation-induced immune priming in CRC. Blockade of the phagocytosis checkpoints SIRPα and PD-1 during radiotherapy promotes vigorous anti-CRC immune priming leading to systemic tumor regression.

Acknowledgements

This study is supported in part by NIH grant P30 CA16672, the MD Anderson Andrew Sabin Family Fellowship, and Chang Gung Memorial Hospital grant CMRPG3K1751. RCH was supported by the CPRIT Research Training Grant (RP170067) and Ralph B. Arlinghaus Ph.D. Scholarship. The authors are grateful to the members of the Advanced Cytometry & Sorting Facility at South Campus, Tissue Bank of Chang Gung Memorial Hospital at Linkou, and MHC Tetramer Core Facility at Baylor College of Medicine for their invaluable help.

Ethics Approval

This study was approved by the Institutional Review Board of Chang Gung Memorial Hospital, Taiwan; approval number: 202001191B0C601.

291 Dual-specific antibodies blocking both PD-L1 and PD-L2 engagement of PD-1 restore anti-tumor immunity

Background

Inhibition of T cell activation and effector function via engagement of the co-inhibitory receptor PD-1 is a critical mechanism enabling tumors to evade host immunity. The two ligands for PD-1, PD-L1 and PD-L2, can be expressed by a variety of immunosuppressive stromal cells, particularly of the myeloid lineage, endothelial cells, and by tumors themselves. In addition to PD-1, PD-L1 engages B7-1 in an additional co-inhibitory interaction. Blocking only PD-1 or only PD-L1 thus does not relieve all inhibitory components of this pathway. We hypothesized that bispecific antibodies blocking both PD-L1 and PD-L2 could more fully restore tumor-specific T cell activation and potentiate anti-cancer immunotherapy. Furthermore, we speculated that enhancing the cytotoxic effector function of these antibodies might further enhance their efficacy through the depletion of tumor cells and supportive stroma.

Methods

We investigated the capacity of monoclonal antibodies capable of bivalent binding to both PD-L1 and PD-L2 to restore the function of PD-1-suppressed T cells in vitro. To assess the in vivo therapeutic efficiency of bispecific PD-Ligand antibodies with ADCC capacities, mouse IgG2a and modified human IgG1 versions were generated. We assessed their ADCC activity in vitro using a bioluminescent reporter assay, and their therapeutic efficiency in vivo in syngeneic or human-cell derived tumors.

Results

The bispecific antibodies we generated restore the function of PD-1-suppressed T cells in vitro with equivalent efficiency to the FDA approved PD-1 antibody Pembrolizumab. Moreover, our modified human bispecific antibodies lead to significantly higher FcγRIIa activation than FDA-approved clinical human IgG1 PD-L1 antibodies in vitro. In vivo, ADCC-capable PD-Ligand bispecific antibodies suppress the growth of U2940 lymphoma in immunodeficient mice more efficiently than Rituximab, and in a syngeneic model of PD-L1/PD-L2 double positive colon carcinoma, these antibodies demonstrate superiority to PD-1 blocking antibodies to limit tumor growth and increase survival. Furthermore, treatment with our bispecific antibodies increases T cell proliferation and cytotoxicity and reduces density of immunosuppressive myeloid stroma in vivo.

Conclusions

ADCC-capable PD-Ligand bispecific antibodies display higher therapeutic potential than existing anti-PD-1 antibodies and represent a new class of PD-1 pathway therapeutics with significant potential for the treatment of a variety of human cancers.

Acknowledgements

I would like to thank Anupallavi Srinivasamani, PhD student in Michael Curran’s lab, who performed a considerable amount of the work on this project before I joined.

IFN-III is selectively produced by cDC1 and predicts good clinical outcome in breast cancer

Dendritic cells play a key role in the orchestration of antitumor immune responses. The cDC1 (conventional dendritic cell 1) subset has been shown to be essential for antitumor responses and response to immunotherapy, but its precise role in humans is largely unexplored. Using a multidisciplinary approach, we demonstrate that human cDC1 play an important role in the antitumor immune response through their capacity to produce type III interferon (IFN-λ). By analyzing a large cohort of breast primary tumors and public transcriptomic datasets, we observed specific production of IFN-λ1 by cDC1. In addition, both IFN-λ1 and its receptor were associated with favorable patient outcomes. We show that IFN-III promotes a T_H1 microenvironment through increased production of IL-12p70, IFN-γ, and cytotoxic lymphocyte-recruiting chemokines. Last, we showed that engagement of TLR3 is a therapeutic strategy to induce IFN-III production by tumor-associated cDC1. These data provide insight into potential IFN- or cDC1-targeting antitumor therapies.

Abstract A70: IFN-III is selectively produced by cDC1 and predicts good clinical outcome in human breast cancer

Dendritic cells (DCs) play a key role in the orchestration of antitumor immune responses. The cDC1 subset was demonstrated as essential for tumor control and response to immunotherapies in mice, but its precise role in human is largely unexplored. In our study, we combined the analysis of large cohorts of fresh breast and ovarian primary tumors and of public transcriptomic data sets to elucidate human cDC1 functions and clinical impact compared with other DC subsets. We identified a key role for intratumoral cDC1 in producing selectively type III interferon (IFN-III), strongly associated with cytokines and chemokines promoting cytotoxic immune cell recruitment and activation. Of utmost importance, we also revealed a positive impact of IFN-III and cDC1 on patient outcome in many human cancers and identified TLR3-triggering as a therapeutic strategy to trigger IFN-III production by tumor-associated cDC1. These data may pave the way for new IFN or cDC1-targeting antitumor therapies.

Citation Format: Margaux Hubert, Coline Couillault, Thien Phong Vu Manh, Vincent Ollion, Helene Lopez-Mestre, Nabil Rahmouni, Janice KIielbassa, Celine Rodriguez, Christophe Sajous, Benoit Dumont, Anne-Claire Doffin, Isabelle Treilleux, Olivier Tredan, Marc Dalod, Nathalie BendrissS-Vermare, Christophe Caux, Jenny Valladeau-Guilemomd. IFN-III is selectively produced by cDC1 and predicts good clinical outcome in human breast cancer [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A70.

Identification of Tertiary Lymphoid Structure-Associated Follicular Helper T Cells in Human Tumors and Tissues

Follicular helper T (Tfh) cells are major components of the humoral immune response due to their pivotal role in germinal center formation and antibody affinity maturation following B-cell isotype switching. This CD4⁺ T-cell subtype is mainly found in the B-cell zone of secondary lymphoid organs as well as in tertiary lymphoid structures (TLS), which are highly organized structures composed of T and B cells, occasionally found at the invasive margin in the tumor microenvironment.We describe here how to perform immunofluorescence staining of tumor tissue sections and multicolor flow cytometry on tumor cell suspensions to identify and visualize these TLS-associated Tfh cells within the tumor microenvironment of various human cancers. These assays take advantage of combinations of markers and molecules involved in Tfh differentiation and function.

Immunopathological characterization of ovarian teratomas associated with anti-N-methyl-D-aspartate receptor encephalitis

Encephalitis with anti-NMDAR antibodies (NMDAR-E) is a severe autoimmune neurological disorder, defined by a clinical presentation of encephalitis and the presence of IgG targeting the GluN1 subunit of NMDA receptors in the CSF. An underlying ovarian teratoma is commonly associated with this autoimmune disease suggesting a role of the tumor in immunopathogenesis. In this study, we characterized the salient histopathological features of 27 ovarian teratomas associated with NMDAR-E (3 immature and 24 mature teratomas) and 40 controls without associated encephalitis. All but one NMDAR-E-associated teratomas contained a nervous tissue component, while less than 40% of control teratomas did (p < 0.001). GluN1 expression by teratomatous nervous tissue seemed to be more often glial in NMDAR-E teratomas than in control teratomas (73% vs. 29%, p < 0.05). Strikingly, 3 out of 24 NMDAR-E-associated mature teratomas contained neuroglial tissue exhibiting histopathological features of central nervous system neuroglial tumor, while such glioma-like features are exceptionally described in the literature on ovarian teratomas. Moreover, NMDAR-E associated teratomas differed from sporadic ovarian teratomas by consistent and prominent infiltration of the nervous tissue component by immune cells, comprised of T- and B-cells and mature dendritic cells organized in tertiary lymphoid structures, with IgG and IgA deposits and plasma cells in close contact to the neuroglial tissue.

These data demonstrate an association between massive infiltration of NMDAR-E-associated teratomas by immune cells and particular glial features of its neuroglial component, suggesting that this glial tissue might be involved in triggering or sustaining the anti-tumor response associated with the auto-immune neurological disease.

Mouse and Human Liver Contain Immunoglobulin A-Secreting Cells Originating From Peyer's Patches and Directed Against Intestinal Antigens

BACKGROUND & AIMS

The liver receives blood from the gastrointestinal tract through the portal vein, and thereby is exposed continuously to dietary antigens and commensal bacteria. Alcoholic liver disease (ALD) is associated with intestinal dysbiosis, increased intestinal permeability, release of microbes into the portal circulation, and increased serum levels and liver deposits of IgA. We characterized B-cell production of IgA in livers of mice at homeostasis, after oral immunization, in a mouse model of ALD and in human liver samples.

METHODS

We performed studies with Balb/c and C57BL/6-Ly5.1 mice, as well as transgenic mice (quasimonoclonal, activation-induced [cytidine] deaminase-Cre-tamoxifen-dependent estrogen receptor 2 [ERT2], Blimp-1-green fluorescent protein [GFP]). C57BL/6-Ly5.1 mice were fed chronic plus binge ethanol to create a model of ALD. Some mice also were given repeated injections of FTY720, which prevents egress of IgA-secreting cells from Peyer's patches. We obtained nontumor liver tissues from patients with colorectal carcinoma undergoing surgery for liver metastases or hepatocellular carcinoma. B cells were isolated from mouse and human liver tissues and analyzed by flow cytometry and enzyme-linked ImmunoSpot (ELISpot). In wild-type and transgenic mice, we traced newly generated IgA-secreting cells at steady state and after oral immunization with 4-hydroxy-3-nitrophenylacetyl (NP)-Ficoll or cholera toxin. IgA responses were also evaluated in our model of ALD.

RESULTS

Livers of control mice contained proliferative plasmablasts that originated from Peyer's patches and produced IgAs reactive to commensal bacteria. After oral immunization with cholera toxin or a thymus-independent antigen, a substantial number of antigen-specific IgA-secreting cells was found in the liver. Mice fed ethanol had features of hepatitis and increased numbers of IgA-secreting cells in liver, compared with mice given control diets, as well as higher levels of serum IgA and IgA deposits in liver sinusoids. Injection of FTY720 during ethanol feeding reduced liver and serum levels of IgA and IgA deposits in liver and prevented liver injury. Human liver tissues contained a significant proportion of IgA-producing plasma cells that shared phenotypic and functional attributes with those from mouse liver, including reactivity to commensal bacteria.

CONCLUSIONS

Based on studies of mice and human liver tissues, we found the liver to be a site of IgA production by B cells, derived from gut-associated lymphoid tissues. These IgAs react with commensal bacteria and oral antigens. Livers from mice with ethanol-induced injury contain increased numbers of IgA-secreting cells and have IgA deposits in sinusoids. IgAs in the liver could mediate clearance of gut-derived antigens that arrive through portal circulation at homeostasis and protect these organs from pathogens.

Genetic evidence for the role of plasmacytoid dendritic cells in systemic lupus erythematosus

Genetic impairment of plasmacytoid dendritic cells ameliorates autoantibody production and symptoms of SLE in mice.

Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by the production of antibodies to self-nucleic acids, immune complex deposition, and tissue inflammation such as glomerulonephritis. Innate recognition of self-DNA and -RNA and the ensuing production of cytokines such as type I interferons (IFNs) contribute to SLE development. Plasmacytoid dendritic cells (pDCs) have been proposed as a source of pathogenic IFN in SLE; however, their net contribution to the disease remains unclear. We addressed this question by reducing gene dosage of the pDC-specific transcription factor E2-2 (Tcf4), which causes a specific impairment of pDC function in otherwise normal animals. We report that global or DC-specific Tcf4 haplodeficiency ameliorated SLE-like disease caused by the overexpression of the endosomal RNA sensor Tlr7. Furthermore, Tcf4 haplodeficiency in the B6.Sle1.Sle3 multigenic model of SLE nearly abolished key disease manifestations including anti-DNA antibody production and glomerulonephritis. Tcf4-haplodeficient SLE-prone animals showed a reduction of the spontaneous germinal center reaction and its associated gene expression signature. These results provide genetic evidence that pDCs are critically involved in SLE pathogenesis and autoantibody production, confirming their potential utility as therapeutic targets in the disease.

Effect of age, period of diagnosis and birth cohort on large bowel cancer incidence in a well-defined French population, 1976-1995

The objective of this study was to present trends in colorectal cancer incidence by sex and subsite in a well-defined French population. All of the 4486 large bowel cancer cases registered between 1976 and 1995 in the Burgundy registry of digestive tract cancers was included in this study. Time trends in colorectal cancer incidence were analysed over the 1976-95 period. The effects of age, period and cohort were evaluated using a log-linear Poisson model. The incidence rates for right colon cancer increased over time: + 21.6% (95% CI: + 13.5; + 29.7) per 5-year period in males and +10.4% (95% CI: + 3.4; + 17.3) in females. Left colon cancer rates increased in males (+ 10.6% 95% CI: + 4.6; + 16.6). Left colon cancer in females and rectal cancer incidence rates did not significantly change. Between the 1901 cohort to the 1941 cohort, estimated cumulative risks for right colon cancer increased sharply. The increase was less marked for left colon and the cumulative risk for rectal cancer remained almost stable. Temporal trends were different by subsites and sexes. In conclusion, our results confirm the existence of different trends in colorectal cancer incidence between subsites and sexes. These differences probably reflect aetiological distinctions.

Caenorhabditis elegans is a model host for Salmonella typhimurium

The idea of using simple, genetically tractable host organisms to study the virulence mechanisms of pathogens dates back at least to the work of Darmon and Depraitère [1]. They proposed using the predatory amoeba Dictyostelium discoideum as a model host, an approach that has proved to be valid in the case of the intracellular pathogen Legionella pneumophila [2]. Research from the Ausubel laboratory has clearly established the nematode Caenorhabditis elegans as an attractive model host for the study of Pseudomonas aeruginosa pathogenesis [3]. P. aeruginosa is a bacterium that is capable of infecting plants, insects and mammals. Other pathogens with a similarly broad host range have also been shown to infect C. elegans [3,4]. Nevertheless, the need to determine the universality of C. elegans as a model host, especially with regards pathogens that have a naturally restricted host specificity, has rightly been expressed [5]. We report here that the enterobacterium Salmonella typhimurium, generally considered to be a highly adapted pathogen with a narrow range of target hosts [6], is capable of infecting and killing C. elegans. Furthermore, mutant strains that exhibit a reduced virulence in mammals were also attenuated for their virulence in C. elegans, showing that the nematode may constitute a useful model system for the study of this important human pathogen.

Molecular analysis of the trimethylamine N-oxide (TMAO) reductase respiratory system from a Shewanella species

Trimethylamine N-oxide (TMAO) is an abundant compound of tissues of marine fish and invertebrates. During fish spoilage, certain marine bacteria can reduce TMAO to nauseous trimethylamine (TMA). One such bacterium has been isolated and identified as a new Shewanella species, and called Shewanella massilia. The anaerobic growth of S. massilia is greatly increased when TMAO is added, indicating that TMAO reduction involves a respiratory pathway. The TorA enzyme responsible for TMAO reduction is a molybdenum cofactor-containing protein of 90 kDa located in the periplasm. Whereas TorA is induced by both TMAO and dimethylsulfoxide (DMSO), this enzyme has a high substrate specificity and appears to only efficiently reduce TMAO as a natural compound. The structural torA gene encoding the TMAO reductase (TorA) and its flanking regions were amplified using PCR techniques. The torA gene is the third gene of a TMAO-inducible operon (torECAD) encoding the TMAO respiratory components. The torC gene, located upstream from torA encodes a pentahemic c-type cytochrome, likely to be involved in electron transfer to the TorA terminal reductase. TorC was shown to be anchored to the membrane and, like TorA, is induced by TMAO. Except for the TorE protein, which is encoded by the first gene of the torECAD operon, all the tor gene products are homologous to proteins found in the TMAO/DMSO reductase systems from Escherichia coli and Rhodobacter species. In addition, the genetic organization of these systems is similar. Although these bacteria are found in different ecological niches, their respiratory systems appear to be phylogenetically related, suggesting that they come from a common ancestor.

[Superficial cancer of the stomach: evolution of their characteristics over a 20 year period in one population]

OBJECTIVES

The aim of this study was to analyse the incidence, treatment and prognosis of early gastric cancer in a population-based series and to draw a picture of time trends.

METHODS

Over a 20-year period (1976-1995), 80 early gastric cancers were diagnosed in the Côte-d'Or area (493,000 residents). Incidence rates were calculated by sex, age groups and 5-year periods. Prognostic factors were determined using the Kaplan-Meier method and the Cox model.

RESULTS

Age-standardized incidence rates were 0.8/100,000 in men and 0.3/100,000 in women. Incidence increased slightly over time (NS) and their proportion among gastric cancers increased from 3.4% (1976-1980) to 7.9% (1991-1995) (P < 0.01). Among these cancers, 25 were intramucosal (31.3%), 55 were submucosal (68.8%) and 8 had lymph node metastases (10.0%). Overall 21 patients (24.1%) had already been treated for a peptic ulcer. The 5-year crude survival rate was 63.1% and the corresponding net survival rate was 86.3%. Lymph node metastases, location, sex and cancer extension and age were independent prognostic factors.

CONCLUSIONS

Though it is on the increase, the proportion of early gastric cancers remains low among gastric cancers. This study confirms the importance of performing a gastroscopy with biopsy upon each bout of ulcer and that the prognosis is lower than suggested by hospital based series.

Population-based study of diagnosis, treatment and prognosis of gastric cancer

BACKGROUND

Gastric cancer remains a common cancer with a poor prognosis. Improving trends seen in Japan have not yet been observed in Western countries.

METHODS

A population-based series of 1329 patients with gastric cancer diagnosed over an 18-year period in Côte d'Or, France, was used to establish time trends in diagnostic strategy, treatment and prognosis.

RESULTS

The use of endoscopy alone increased from 2.7 per cent in 1976-1978 to 76.6 per cent in 1991-1993 (P < 0.0001). This trend was associated at first with a significant decrease in the use of radiography alone, then by a significant decrease in the use of both radiography and endoscopy. The proportion of resections for cure increased from 37.9 per cent in 1976-1978 to 50.0 per cent in 1991-1993 (mean 3-year variation + 5.8 per cent, P < 0.01). The proportion of cases confined to the gastric wall increased from 6.1 to 11.7 per cent (mean 3-year variation + 13.1 per cent, P < 0.01), while the proportion of other stages remained stable. The operative mortality rate decreased dramatically from 25.6 per cent in 1976-1978 to 13.6 per cent in 1991-1993 (P < 0.001) and the 5-year relative survival rate rose from 12.8 per cent in 1976-1978 to 26.4 per cent in 1988-1990 (P < 0.001).

CONCLUSION

This study has demonstrated that improvements in the care of patients with gastric cancer have been achieved, but that further progress may be made.

Non-Hodgkin's lymphoma: time trends for incidence and survival in Côte-d'Or, France

BACKGROUND

A generally reported increased incidence of non-Hodgkin's lymphomas (NHL) and a recent evolution in treatment strategies, as well as several clinical trials suggesting improved survival, have prompted this study to evaluate time trends in incidence and prognosis of NHL.

METHOD

NHL recorded by the population-based Registry of Hematopoietic Malignancies in Côte-d'Or (France) were considered over three 4-year periods from 1980 to 1992. A multivariate survival analysis was carried out in terms of both crude and relative survivals.

RESULTS

Overall incidence, increased over the 12 years considered, by an average of 6.8% per annum (P < 0.05). Only two cases of AIDS-related NHL were registered during this period. NHL incidence has increased slightly more for males than for females, further widening the gap in incidence between the sexes. In terms of histological grade the increase in incidence was more pronounced for low-grade and high-grade NHL than for intermediate-grade NHL. The overall 5-year relative survival rate was 69.3%. In multivariate relative survival analysis, neither sex, age, period of diagnosis nor place of hospitalization were significant prognostic factors. Only place of residence, with RR 2.2 (1.41-3.42) for people living in rural areas compared to urban areas and histological type, according to the working formulation with RR 3.8 (2.22-6.61) for high-grade tumours compared to low-grade tumours, remained informative for prognosis.

CONCLUSIONS

Although incidence of NHL has increased in Côte-d'Or, this trend has remained independent of the AIDS epidemic. Contrary to the findings of clinical trials, the patients' survival in this population-based series has not been shown to have improved over the study period.

Chemoprevention of metachronous adenomas of the large bowel: design and interim results of a randomized trial of calcium and fibre. ECP Colon Group

A European multicentric intervention study, led by the colon group of the European Cancer Prevention Organization, is under way. The main aim of the study is to test the efficacy of oral calcium supplementation with 2 g calcium per day and oral dietary supplementation with mucilaginous substances (as 3.8 g of ispaghula husk) on adenoma recurrence. Secondary aims are the study of treatment efficacy on colonic cell proliferation and on stool bile acid and sterol concentration. Serum and plasma samples are also collected. To better interpret the effect of the intervention, a diet history questionnaire and an aspirin and anti-inflammatory drug questionnaire are administered. The aim will be achieved through a randomized placebo-controlled clinical trial using a parallel design in patients aged 35 to 75 at entry with a complete colonoscopy and a clean colon. Overall, 655 subjects have been included. All randomized patients are followed up every six months for 3 years. If one of the evaluated interventions proves efficient, the benefits of a simple, safe and inexpensive prophylaxy for a very common cancer will be clear.

Environmental and familial risk factors in relation to the colorectal adenoma--carcinoma sequence: results of a case-control study in Burgundy (France)

A case-control study in the Cote-d'Or area (Burgundy, France) investigated the relationship between environmental and familial risk factors and the different steps of the adenoma-carcinoma sequence. Two adenoma groups (< 10 mm and > or = 10 mm), a polyp-free control group, a colorectal cancer group and a general population control group were recruited. Tobacco was associated with the risk of adenomas, and alcohol with the risk of large adenomas. They proved to be independently related to large adenoma formation when compared with controls. There was no association with cancer risk. Refined cereals, delicatessen, offal and fats appear to be risk factors along the adenoma-carcinoma sequence. This data does not support an increased risk with high consumption of fresh meat, or a protective effect of dairy products and calcium. A high consumption of vegetables was a protective factor for cancer, mainly in men. Excess weight and body mass index influenced the earlier step of the adenoma carcinoma sequence and excess calorie intake was risk factor for cancer. The decision to study precancerous lesions as well as cancer appears fruitful. Results suggest that the three stages of large bowel carcinogenesis are partly related to diet in different ways. They are concordant with risk factors recorded for colorectal cancer, but suggest some local specificities.

Time trends in diagnostic strategy, treatment, and prognosis of gastric cancer in the elderly: a population based study

The impact of changes in diagnostic strategies for gastric cancer and attitudes towards surgery in elderly patients is not known. A population-based series of 842 gastric cancers diagnosed between 1976 and 1993 in patients aged 70 and older in Côte-dOr, France, was used to establish trends in diagnostic strategy, treatment, and prognosis. The use of endoscopy alone increased from 3% (1976-78) to 81% (1991-93). This trend was initially associated with a decrease in the use of x-ray alone, then with a decrease in the use of both x-ray and endoscopy. The proportion of resection for cure increased from 26% during 1976-78 to 43% during 1991-93 (P < 0.001). The proportion of cancers not extending beyond the gastric wall increased from 12% to 24% (P < 0.05). Operative mortality decreased from 38.7% (1976-78) to 13.3% (1991-93) and the corresponding 3-year crude survival rate rose from 7% to 18%. Improvements in the care of gastric cancer in elderly patients have been achieved, but further progress is warranted.

Calcium, phosphorus, vitamin D, dairy products and colorectal carcinogenesis: a French case--control study

A protective effect of calcium against colorectal cancer has been described in Anglo-Saxon but not in Latin communities, and no such effect has been observed regarding adenomas. We investigated the relationship between calcium, dairy products and the adenoma-carcinoma sequence in a French region by comparing small adenoma ( < 10 mm, n = 154), large adenoma (n = 208) and polyp-free (n = 426) subjects, and cancer cases (n = 171) with population controls (n = 309). There was no protective effect of calcium against colorectal tumours except for low fat calcium and large adenomas in men (OR for highest quintile = 0.3, P for trend = 0.06). There was even a trend towards an increased risk of cancer with dairy calcium in men and non-dairy calcium in women. Vitamin D was inversely related to the risk of small adenomas in women (OR for highest quintile = 0.4, P for trend = 0.04). Regarding dairy products, only consumption of yoghurt displayed an inverse relationship with risk of large adenomas, in both men and women. These data failed to demonstrate a protective effect of calcium against colorectal carcinogenesis. They suggest that the type of dairy product might be the important factor with regard to prevention of colorectal tumours.

Intervention trials on colorectal cancer prevention

Epidemiological studies have emphasized the major role played by diet in the etiology of large-bowel cancer. Attempts to identify causative or protective factors in epidemiological and experimental studies have led to some discrepancies. The time has come to test the most important hypotheses within the framework of intervention studies. Of 14 studies specifically devoted to colorectal carcinogenesis, nine have been completed and five are ongoing; all the studies evaluate the effect of the intervention on adenoma recurrence and three studies also examine adenoma growth. In addition, five intervention trials considering cardiovascular diseases and various cancer sites will provide data on the effect of the intervention on colorectal cancer incidence. The interventions being evaluated are supplements of vitamins (with or without other antioxidants), fibre or calcium, as well as dietary modifications. Most available data do not support a protective effect of vitamins and antioxidants on colorectal carcinogenesis. There are some arguments in favour of a protective effect of dietary fibre and/or a low-fat diet on adenoma growth. The results of ongoing studies will be available within two to three years. If one of the evaluated interventions proves effective, it will indicate a simple, safe and inexpensive prophylaxis for a very common cancer.

Folate and alcohol intakes: related or independent roles in the adenoma-carcinoma sequence?

Epidemiologic studies have suggested that high alcohol and low folate intakes might be jointly associated with colorectal tumors via DNA metabolism. We investigated this hypothesis in a case-control study comparing small adenoma (< 10 mm, n = 154), large adenoma (n = 208), and polyp-free (n = 426) subjects, recruited after colonoscopy, and cancer cases (n = 171) with population controls (n = 309). Odds ratios for the fifth vs. the first quintile of intake (OR5) were as follows: Folate intake was related to the risk of small and large adenomas compared with polyp-free subjects [OR5 = 0.5, 95% confidence interval (CI) 0.3-1.0; OR5 = 0.5, 95% CI 0.3-1.0, respectively], whereas alcohol was related to risk of large adenomas (OR5 = 4.1, 95% CI 2.1-8.1), but not of small adenomas (OR5 = 1.2, 95% CI 0.7-2.2). In large adenomas, there was some interaction between alcohol and folate, with a stronger protective effect of folate with high alcohol intake and a stronger risk with alcohol with low folate intake. For cancer patients compared with general population controls, neither alcohol (OR5 = 1.6, 95% CI 0.8-3.0) nor folates (OR5 = 1.0, 95% CI 0.5-2.0) were related to risk. Our data support the hypothesis that folate intake might be mostly beneficial to prevent adenoma formation but might have an additional protective effect against adenoma growth associated with alcohol.

[Primary prevention of colorectal cancer]

Results from case-control studies and prospective studies suggest that diet is involved in the causation of large bowel cancer either as initiator, promoter or inhibitor of carcinogenesis. Available data are not sufficient to serve as a basis for firm specific dietary advice. In the present situation it is attractive to investigate available hypotheses within the frame work of intervention trials. The adenoma appears to be one of the most appropriate end point of intervention studies. Several arguments indicate that the adenoma-carcinoma sequence is a multistep process. Colorectal cancer could possibly be prevented by intervening in the development of a small adenoma or in the growth into a large adenoma. Four intervention trials have been published so far. One of them suggest a protective effect of antioxidants vitamins on adenoma recurrence and three of them conclude to the absence of effect of these vitamins. A protective effect of lactulose on adenoma recurrence has also been suggested. Three studies are currently evaluating the effect of calcium supplementation on adenoma recurrence or growth of calcium supplementation, three studies the effect of fibre supplements, two studies the effect of antioxidants (one of them with calcium) and two studies the effect of diet intervention. The results of these studies will be available within three years.