Characterizing the cancer-associated microbiome with small RNA sequencing data.

The microbiome is recognized as a quasi-organ in the human body. When dysbiosis of the microbiome occurs, this variation may contribute to alterations in the microenvironment, potentially inducing an inflammatory immune response and providing a niche for neoplastic growth. However, there is limited evidence regarding the correlation and interaction between the microbiome and tumorigenesis. By utilizing microRNA sequencing data of patients with colon and rectal cancer from The Cancer Genome Atlas, we designed a novel analytical process to extract non-human small RNA sequences and align them with the microbial genome to obtain a comprehensive view of the cancer-associated microbiome. In the present study, we identified >1000 genera among 630 colorectal samples and clustered these samples into three distinctive colorectal enterotypes. Furthermore, we found 12 genera from these clusters that are associated with cancer stages and revealed their putative functions. Our results indicate that the proposed analytical approach can effectively determine the cancer-associated microbiome. It may be readily applied to explore other types of cancer, in which specimens of the microbiome are difficult to collect.

Stool Microbiota Composition Differs in Patients with Stomach, Colon, and Rectal Neoplasms.

BACKGROUND: Microbial ecosystems that inhabit the human gut form central component of our physiology and metabolism, regulating and modulating both health and disease. Changes or disturbances in the composition and activity of this gut microbiota can result in altered immunity, inflammation, and even cancer. AIM: To compare the composition and diversity of gut microbiota in stool samples from patient groups based on the site of neoplasm in the gastrointestinal tract (GIT) and to assess the possible contribution of the bacterial composition to tumorigenesis. METHODS: We studied gut microbiota by16S RNA gene sequencing from stool DNA of 83 patients, who were diagnosed with different GIT neoplasms, and 13 healthy individuals. RESULTS: As compared to healthy individuals, stools of patients with stomach neoplasms had elevated levels of Enterobacteriaceae, and those with rectal neoplasms had lower levels of Bifidobacteriaceae. Lower abundance of Lactobacillaceae was seen in patients with colon neoplasms. Abundance of Lactobacillaceae was higher in stools of GIT patients sampled after cancer treatment compared to samples collected before start of any treatment. In addition to site-specific differences, higher abundances of Ruminococcus, Subdoligranulum and lower abundances of Lachnoclostridium and Oscillibacter were observed in overall GIT neoplasms as compared to healthy controls CONCLUSION: Our study demonstrates that the alterations in gut microbiota vary according to the site of GIT neoplasm. The observed lower abundance of two common families, Lactobacillaceae and Bifidobacteriaceae, and the increased abundance of Enterobacteriaceae could provide indicators of compromised gut health and potentially facilitate GIT disease monitoring.

Tumour-associated and non-tumour-associated microbiota in colorectal cancer.

OBJECTIVE: A signature that unifies the colorectal cancer (CRC) microbiota across multiple studies has not been identified. In addition to methodological variance, heterogeneity may be caused by both microbial and host response differences, which was addressed in this study. DESIGN: We prospectively studied the colonic microbiota and the expression of specific host response genes using faecal and mucosal samples ('ON' and 'OFF' the tumour, proximal and distal) from 59 patients undergoing surgery for CRC, 21 individuals with polyps and 56 healthy controls. Microbiota composition was determined by 16S rRNA amplicon sequencing; expression of host genes involved in CRC progression and immune response was quantified by real-time quantitative PCR. RESULTS: The microbiota of patients with CRC differed from that of controls, but alterations were not restricted to the cancerous tissue. Differences between distal and proximal cancers were detected and faecal microbiota only partially reflected mucosal microbiota in CRC. Patients with CRC can be stratified based on higher level structures of mucosal-associated bacterial co-abundance groups (CAGs) that resemble the previously formulated concept of enterotypes. Of these, Bacteroidetes Cluster 1 and Firmicutes Cluster 1 were in decreased abundance in CRC mucosa, whereas Bacteroidetes Cluster 2, Firmicutes Cluster 2, Pathogen Cluster and Prevotella Cluster showed increased abundance in CRC mucosa. CRC-associated CAGs were differentially correlated with the expression of host immunoinflammatory response genes. CONCLUSIONS: CRC-associated microbiota profiles differ from those in healthy subjects and are linked with distinct mucosal gene-expression profiles. Compositional alterations in the microbiota are not restricted to cancerous tissue and differ between distal and proximal cancers.

Effect of abdominopelvic sepsis on cancer outcome in patients undergoing sphincter saving surgery for rectal cancer.

BACKGROUND: In rectal cancer, the significance of abdominopelvic sepsis (APS) on metastatic tumor growth remains uncertain. We aimed to analyze the effect of abdominopelvic sepsis on long-term survival in patients undergoing restorative rectal cancer surgery. METHODS: Data were used from the Belgian PROCARE rectal cancer registry. The effect of abdominopelvic infection on survival was assessed in uni- and multivariable Cox regression models. The effect of clinical and pathological covariates was controlled by propensity score-based matching of cases with controls. The effect of abdominopelvic sepsis on the rate of local and metastatic recurrence was evaluated using crosstabulation and the Pearson χ2 test. RESULTS: In univariable analysis, the presence of APS was associated with significantly worse overall survival (HR 1.3, P = 0.025). After propensity score matching including age, BMI, tumor level, pTstage, pN stage, CRM, tumor grade, number of lymph nodes, and presence of lymphovascular invasion, the association of APS with OS was no longer significant (HR 1.26, 95%CI 0.92-1.74, P = 0.15). No differences were observed in the risk of local or metastatic recurrence (3.6% vs 2.9% and 13% vs 16.5%). CONCLUSIONS: In this analysis APS after rectal cancer resection was not significantly associated with OS, metastatic, or local recurrence.

Mucosa-associated lymphoid tissue (MALT) variant of primary rectal lymphoma: a review of the English literature.

PURPOSE: Primary rectal lymphoma (PRL) is the third most common cause of rectal cancer following adenocarcinoma (90-95 %) and carcinoid (5 %). The most common variant of PRL is the mucosa-associated lymphoid tissue (MALT) type. To date, no study has been able to recommend an optimal treatment algorithm for this rare disease. The aim of our study was to review the English literature on primary rectal MALT lymphoma. METHODS: A review of the English literature was conducted to identify articles describing the MALT variant of PRL. RESULTS: Fifty-one cases were identified. A complete response was achieved in 12 of 19 cases treated with Helicobacter pylori eradication therapy, 5 of 6 with radiation, 2 of 4 cases with chemotherapy, 2 of 4 with endoscopic resection, 6 of 8 cases with surgical resection, and all 8 with combination therapies. Cases failing initial therapies were responsive to various second-line treatments. Two cases spontaneously regressed with observation alone. CONCLUSION: Complete regression of primary rectal MALT lymphoma was achieved using various therapeutic strategies, although the numbers of different treatment modalities are too small to draw definitive conclusions.

Spatial transcriptomic analysis reveals local effects of intratumoral fusobacterial infection on DNA damage and immune signaling in rectal cancer.

Mucinous colorectal cancer (CRC) is a common histological subtype of colorectal adenocarcinoma, associated with a poor response to chemoradiotherapy. The commensal facultative anaerobes fusobacteria, have been associated with poor prognosis specifically in mesenchymal CRC. Interestingly, fusobacterial infection is especially prevalent in mucinous CRC. The objective of this study was therefore to increase our understanding of beneficial and detrimental effects of fusobacterial infection, by contrasting host cell signaling and immune responses in areas of high vs. low infection, using mucinous rectal cancer as a clinically relevant example. We employed spatial transcriptomic profiling of 106 regions of interest from 8 mucinous rectal cancer samples to study gene expression in the epithelial and immune segments across regions of high versus low fusobacterial infection. Fusobacteria high regions were associated with increased oxidative stress, DNA damage, and P53 signaling. Meanwhile regions of low fusobacterial prevalence were characterized by elevated JAK-STAT, Il-17, Il-1, chemokine and TNF signaling. Immune masks within fusobacterial high regions were characterized by elevated proportions of cytotoxic (CD8+) T cells (p = 0.037), natural killer (NK) cells (p < 0.001), B-cells (p < 0.001), and gamma delta T cells (p = 0.003). Meanwhile, fusobacteria low regions were associated with significantly greater M2 macrophage (p < 0.001), fibroblast (p < 0.001), pericyte (p = 0.002), and endothelial (p < 0.001) counts.

Gut microbiome model predicts response to neoadjuvant immunotherapy plus chemoradiotherapy in rectal cancer.

BACKGROUND: Accurate evaluation of the response to preoperative treatment enables the provision of a more appropriate personalized therapeutic schedule for locally advanced rectal cancer (LARC), which remains an enormous challenge, especially neoadjuvant immunotherapy plus chemoradiotherapy (nICRT). METHODS: This prospective, multicenter cohort study enrolled patients with LARC from 6 centers who received nICRT. The dynamic variation in the gut microbiome during nICRT was evaluated. A species-level gut microbiome prediction (SPEED) model was developed and validated to predict the pathological complete response (pCR) to nICRT. FINDINGS: A total of 50 patients were enrolled, 75 fecal samples were collected from 33 patients at different time points, and the pCR rate reached 42.4% (14/33). Lactobacillus and Eubacterium were observed to increase after nICRT. Additionally, significant differences in the gut microbiome were observed between responders and non-responders at baseline. Significantly higher abundances of Lachnospiraceae bacterium and Blautia wexlerae were found in responders, while Bacteroides, Prevotella, and Porphyromonas were found in non-responders. The SPEED model showcased a superior predictive performance with areas under the curve of 98.80% (95% confidence interval [CI]: 95.67%-100%) in the training cohort and 77.78% (95% CI: 65.42%-88.29%) in the validation cohort. CONCLUSIONS: Programmed death 1 (PD-1) blockade plus concurrent long-course CRT showed a favorable pCR rate and is well tolerated in microsatellite-stable (MSS)/mismatch repair-proficient (pMMR) patients with LARC. The SPEED model can be used to predict the pCR to nICRT based on the baseline gut microbiome with high robustness and accuracy, thereby assisting clinical physicians in providing individualized management for patients with LARC. FUNDING: This research was funded by the China National Natural Science Foundation (82202884).

The recovery of intestinal barrier function and changes in oral microbiota after radiation therapy injury.

Introduction: Colorectal cancer (CRC) is the third most common malignant tumor, and neoadjuvant chemo-radiotherapy is usually recommended for advanced stage colorectal cancer. Radiotherapy can cause damage to intestinal mucosal barrier, which may be related to perioperative complications. Intestinal microbiota is one of the constituents of the intestinal mucosal biological barrier, and literature reports that patients with CRC have changes in corresponding oral microbiota. This study aims to analyze the levels of immunoglobulin SIgA, inflammatory factors, lymphocyte subsets quantity, and proportion in surgical specimens of intestinal mucosa at different time intervals after radiotherapy, in order to seek investigation for the optimal surgical time after radiotherapy and to provide evidence for finding probiotics or immunomodulators through high-throughput sequencing of bacterial 16s rRNA in patients' saliva microbiota. Ultimately, this may provide new ideas for reducing perioperative complications caused by radiotherapy-induced intestinal damage. Methods: We selected intestinal mucosal tissue and saliva samples from over 40 patients in our center who did not undergo radiotherapy and underwent surgery at different time intervals after radiotherapy. Detection of SIgA was performed using ELISA assay. Western Blotting was used to detect IL-1ß, IL-6, and IL-17 in the intestinal mucosal tissue. Flow cytometry was used to detect CD4 and CD8. And the microbial community changes in saliva samples were detected through 16s rRNA sequencing. Results: After radiotherapy, changes in SIgA, various cytokines, CD4CD8 lymphocyte subsets, and oral microbiota in the intestinal mucosal tissue of rectal cancer patients may occur. Over time, this change may gradually recover. Discussion: In colorectal cancer, oncological aspects often receive more attention, while studies focusing on the intestinal mucosal barrier are less common. This study aims to understand the repair mechanisms of the intestinal mucosal barrier and reduce complications arising from radiotherapy-induced damage. The relationship between oral microbiota and systemic diseases has gained interest in recent years. However, the literature on the oral microbiota after radiotherapy for rectal cancer remains scarce. This study addresses this gap by analysing changes in the salivary microbiota of rectal cancer patients before and after radiotherapy, shedding light on microbiota changes. It aims to lay the groundwork for identifying suitable probiotics or immunomodulators to alleviate perioperative complications and improve the prognosis of CRC.

Gut Microbiome Components Predict Response to Neoadjuvant Chemoradiotherapy in Patients with Locally Advanced Rectal Cancer: A Prospective, Longitudinal Study.

PURPOSE: The gut microbiome is involved in antitumor immunotherapy and chemotherapy responses; however, evidence-based research on the role of gut microbiome in predicting response to neoadjuvant chemoradiotherapy (nCRT) in patients with locally advanced rectal cancer (LARC) remains scarce. This prospective, longitudinal study aimed to evaluate the feasibility of the gut microbiome in predicting nCRT responses. EXPERIMENTAL DESIGN: We collected 167 fecal samples from 84 patients with LARC before and after nCRT and 31 specimens from healthy individuals for 16S rRNA sequencing. Patients were divided into responders and nonresponders according to pathologic response to nCRT. After identifying microbial biomarkers related to nCRT responses, we constructed a random forest classifier for nCRT response prediction of a training cohort of baseline samples from 37 patients and validated the classifier in another cohort of 47 patients. RESULTS: We observed significant microbiome alterations represented by a decrease in LARC-related pathogens and an increase in Lactobacillus and Streptococcus during nCRT. Furthermore, a prominent microbiota difference between responders and nonresponders was noticed in the baseline samples. Microbes related with butyrate production, including Roseburia, Dorea, and Anaerostipes, were overrepresented in responders, whereas Coriobacteriaceae and Fusobacterium were overrepresented in nonresponders. Ten biomarkers were selected for the response-prediction classifier, including Dorea, Anaerostipes, and Streptococcus, which yielded an area under the curve value of 93.57% [95% confidence interval (CI), 85.76%-100%] in the training cohort and 73.53% (95% CI, 58.96%-88.11%) in the validation cohort. CONCLUSIONS: The gut microbiome offers novel potential biomarkers for predicting nCRT responses, which has important manifestations in the clinical management of these patients.

Changes in Gut Microbiome Associated With Co-Occurring Symptoms Development During Chemo-Radiation for Rectal Cancer: A Proof of Concept Study.

PURPOSE: To examine a) whether there are significant differences in the severity of symptoms of fatigue, sleep disturbance, or depression between patients with rectal cancer who develop co-occurring symptoms and those with no symptoms before and at the end of chemotherapy and radiation therapy (CRT); b) differences in gut microbial diversity between those with co-occurring symptoms and those with no symptoms; and c) whether before-treatment diversity measurements and taxa abundances can predict co-occurrence of symptoms. METHODS: Stool samples and symptom ratings were collected from 31 patients with rectal cancer prior to and at the end of (24-28 treatments) CRT. Descriptive statistics were computed and the Mann-Whitney U test was performed for symptoms. Gut microbiome data were analyzed using R's vegan package software. RESULTS: Participants with co-occurring symptoms reported greater severity of fatigue at the end of CRT than those with no symptoms. Bacteroides and Blautia2 abundances differed between participants with co-occurring symptoms and those with no symptoms. Our random forest classification (unsupervised learning algorithm) predicted participants who developed co-occurring symptoms with 74% accuracy, using specific phylum, family, and genera abundances as predictors. CONCLUSION: Our preliminary results point to an association between the gut microbiota and co-occurring symptoms in rectal cancer patients and serves as a first step in potential identification of a microbiota-based classifier.

[Regression of MALT lymphoma of the rectum after Helicobacter pylori eradication therapy in a patient negative for Helicobacter pylori].

A 53-year-old woman was referred to our hospital for further examination of a rectal polypoid lesion. Colonoscopy revealed a submucosal tumor in the rectum (Ra) and a diagnosis of MALT lymphoma was made on the histological examination of the biopsy specimens and Southern blot analysis of the immunoglobulin heavy chain gene rearrangement. Although the patient was negative for Helicobacter pylori, H. pylori eradication therapy was performed. Colonoscopy 3 months after the eradication therapy showed disappearance of the rectal tumor. H. pylori eradication appears to be a useful treatment for not only H. pylori-positive colonic MALT lymphoma but H. pylori-negative colonic MALT lymphoma.

Gut Microbiome Composition Is Associated with a Pathologic Response After Preoperative Chemoradiation in Patients with Rectal Cancer.

PURPOSE: There are ongoing investigations to find promising biomarkers for predicting a complete response (CR) after concurrent chemoradiation (CCRT) in rectal cancer. We aimed to find the predictive value in the gut microbiome in terms of response after preoperative CCRT. METHODS AND MATERIALS: We collected a total of 45 fecal samples from patients with rectal cancer before CCRT. Tumor response after CCRT was assessed according to the American Joint Committee on Cancer tumor regression grading system. Analysis of linear discriminant analysis effect size and MetaCyc pathway abundance predictions were performed to compare composition and metabolic function of microbiome between patients with and without CR. We also established a Bayesian network model to identify microbial networks and species to be related with CCRT response. RESULTS: Seven patients (15.6%) demonstrated pathologically CR, and 38 patients (84.4%) showed non-CR after preoperative CCRT. Between CR and non-CR patients, there was a significant difference in terms of ß-diversity (P = .028), but no difference in α-diversity was found. Bacteroidales (Bacteroidaceae, Rikenellaceae, Bacteroides) were relatively more abundant in patients with non-CR than those with CR. Pathways related to anabolic function predominated in CR patients. According to Bayesian network analysis, Duodenibacillus massiliensis was linked with the improved CR rate. CONCLUSIONS: From the fecal microbiome using samples obtained before preoperative CCRT, differences in microbial community composition and functions were observed between patients with and without CR in rectal cancer. However, the finding that a specific taxon may be linked with the improved therapeutic response should be verified in a prospective setting.

Gut microbiota differences in Island Hispanic Puerto Ricans and mainland non-Hispanic whites during chemoradiation for rectal cancer: A pilot study.

PURPOSE: To investigate whether there are differences in diversity, taxonomic composition, and predicted functional pathways of the gut microbiome between Island Hispanic Puerto Ricans (HPR) and mainland non-Hispanic whites (NHW) measured before and at the end of chemo-radiation (CRT) for Rectal Cancer. METHODS: Fifty-six stool samples of newly diagnosed rectal cancer patients (25 HPR and 31 NHW) were amplicon-sequenced during chemo-radiotherapy. 16S rRNA gene data was analyzed using QIIME2, phyloseq, and LEfSe. RESULTS: We observed similar within-sample alpha diversity for HPR and NHW participants during CRT. However, at the end of CRT, several taxa were present at significantly different abundances across both groups. Taxa enriched in the gut of HPR compared to NHW included Muribaculaceae, Prevotella 2 and 7, Gemella, Bacillales Family XI, Catenibacterium, Sutterella, Pasteurellales, and Pasteurellaceae genera, whereas over-represented taxa in NHW participants were Turicibacter and Eubacteriaceae. Significant differences in predicted HPR microbiota functions included pathways for synthesis of L-methionine and degradation of phenylethylamine and phenylacetate. CONCLUSION: In this pilot study, taxonomic analyses and functional predictions of the gut microbiomes suggest greater inflammatory potential in gut microbial functions among HPR rectal cancer patients undergoing CRT compared to that of NHW participants.

Contrast radiography before diverting stoma closure in rectal cancer is not necessary on a routine basis. / El estudio radiológico con contraste antes del cierre del estoma derivativo en el cáncer de recto no es necesario de forma rutinaria.

INTRODUCTION: Diverting stomata are recommended in patients with low anterior resection and risk factors in order to reduce the severity of anastomotic leaks. Usually, a radiology study is performed prior to the closure of the stoma to detect subclinical leaks. The aim of the present study is to assess the clinical utility of the radiology study. METHODS: A prospective cohort study of patients undergoing anterior rectal resection for rectal cancer and those who underwent stoma closure without contrast enema. This study was carried out after a retrospective review of radiology study results prior to the closure of the stoma in patients operated from 2007 to 2011. RESULTS: Eighty-six patients met the study criteria. Thirteen patients (15.1%) presented pelvic sepsis. Contrast enema before stoma closure was pathological in 8 patients (9.3%). Five out of the 13 patients with pelvic sepsis had a pathological radiological study, compared to only 3 out of the 73 patients without intra-abdominal complications after rectal resection (38.5% vs. 4.1%; P=.001). Based on these results, we conducted a prospective study omitting the contrast enema in patients with no postoperative complications. Thirty-eight patients had their stoma closed without a prior radiology study. None of the patients presented pelvic sepsis. CONCLUSIONS: Radiology studies of the colorectal anastomosis before reconstruction can safely be omitted in patients without pelvic sepsis after the previous rectal resection.

Sentinel Case of Candida auris in the Western United States Following Prolonged Occult Colonization in a Returned Traveler from India.

Candida auris is an emerging multidrug-resistant yeast with high mortality. We report the sentinel C. auris case on the United States West Coast in a patient who relocated from India. We identified close phylogenetic relatedness to the South Asia clade and ERG11 Y132F and FKS1 S639Y mutations potentially explaining antifungal resistance.

Fecal profiles of anaerobic microflora of large bowel cancer patients and patients with nonhereditary large bowel polyps.

It has been postulated that the intestinal anaerobes play a role in the etiology of large bowel cancer. This study was designed to characterize and compare the fecal anaerobes of patients with large bowel cancer, patients with nonhereditary large bowel polyps, and healthy control subjects. Although some distributional variations of the anaerobic genera were observed among the study groups, significant differences in fecal anaerobic microflora and total aerobic counts were not noted. This suggests that taxonomic grouping of fecal bacteria is an inadequate measure of relative risk of developing large bowel cancer. However, the fecal microbial 7alpha-dehydroxylase and cholesterol dehydrogenase activities of large bowel cancer patients and patients with nonhereditary large bowel polyps were significantly higher than those of healthy control subjects. On the other hand, no significant difference in fecal microbial beta-glucuronidase activity was noted among the study groups. It may be that assessment of the total metabolic activities of the intestinal microflora will provide a better understanding of their potential role in the genesis of large bowel cancer.

Tissue-Associated Bacterial Alterations in Rectal Carcinoma Patients Revealed by 16S rRNA Community Profiling.

Sporadic and inflammatory forms of colorectal cancer (CRC) account for more than 80% of cases. Recent publications have shown mechanistic evidence for the involvement of gut bacteria in the development of both CRC-forms. Whereas, colon and rectal cancer have been routinely studied together as CRC, increasing evidence show these to be distinct diseases. Also, the common use of fecal samples to study microbial communities may reflect disease state but possibly not the tumor microenvironment. We performed this study to evaluate differences in bacterial communities found in tissue samples of 18 rectal-cancer subjects when compared to 18 non-cancer controls. Samples were collected during exploratory colonoscopy (non-cancer group) or during surgery for tumor excision (rectal-cancer group). High throughput 16S rRNA amplicon sequencing of the V4-V5 region was conducted on the Ion PGM platform, reads were filtered using Qiime and clustered using UPARSE. We observed significant increases in species richness and diversity in rectal cancer samples, evidenced by the total number of OTUs and the Shannon and Simpson indexes. Enterotyping analysis divided our cohort into two groups, with the majority of rectal cancer samples clustering into one enterotype, characterized by a greater abundance of Bacteroides and Dorea. At the phylum level, rectal-cancer samples had increased abundance of candidate phylum OD1 (also known as Parcubacteria) whilst non-cancer samples had increased abundance of Planctomycetes. At the genera level, rectal-cancer samples had higher abundances of Bacteroides, Phascolarctobacterium, Parabacteroides, Desulfovibrio, and Odoribacter whereas non-cancer samples had higher abundances of Pseudomonas, Escherichia, Acinetobacter, Lactobacillus, and Bacillus. Two Bacteroides fragilis OTUs were more abundant among rectal-cancer patients seen through 16S rRNA amplicon sequencing, whose presence was confirmed by immunohistochemistry and enrichment verified by digital droplet PCR. Our findings point to increased bacterial richness and diversity in rectal cancer, along with several differences in microbial community composition. Our work is the first to present evidence for a possible role of bacteria such as B. fragilis and the phylum Parcubacteria in rectal cancer, emphasizing the need to study tissue-associated bacteria and specific regions of the gastrointestinal tract in order to better understand the possible links between the microbiota and rectal cancer.

High prevalence of Inoue-Melnick virus antibodies in patients with colorectal carcinoma.

The high prevalence of serum neutralizing antibodies against Inoue-Melnick virus (IMV) among American patients with colorectal carcinoma has been confirmed. Sera from 26 patients with colorectal carcinoma along with the identical number of age- and sex-matched patients with non-colorectal neoplasia and normal healthy controls were collected in the Buffalo area. All of the colorectal carcinoma group possessed antibodies against IMV (100%), while antibody positivity for non-colorectal neoplasia and for normal controls were 34.6% and 38.5%, respectively. Geometric mean titers of antibodies to IMV type 1 and type 2 for colorectal carcinoma were 266 and 338, respectively, whereas the mean titers in the other two control groups were less than 10.3. These differences between colorectal carcinoma and the two controls were highly significant (P less than 0.001). The majority of patients with colorectal carcinoma had antibodies to both IMV types 1 and 2.

Papillomavirus found in anorectal squamous carcinoma, not in colon adenocarcinoma.

We used polymerase chain reaction DNA amplification methods for the detection and typing of genital human papillomaviruses in paraffin-embedded tissue sections of five patients with anorectal squamous cell carcinoma and 22 patients with colonic adenocarcinoma. The cases were further tested by in situ hybridization with biotin-labeled probes specific for human papillomavirus types 6/11, 16/18, and 31/33/35. By polymerase chain reaction, human papillomavirus DNA was demonstrated in all of the cases of anorectal squamous cell carcinoma and in none of the cases of colonic adenocarcinoma for which analyzable DNA was available. Tumor cell nuclei stained for human papillomavirus DNA by in situ hybridization in four of the five cases of squamous cell carcinoma and in none of the cases of colonic adenocarcinoma. We conclude that human papillomavirus types usually associated with malignant transformation are uniformly present in anorectal squamous cell carcinoma but are absent from adenocarcinoma of the colon.