Revealing molecular and cellular heterogeneity in hypopharyngeal carcinogenesis through single-cell RNA and TCR/BCR sequencing.

Introduction: Hypopharyngeal squamous cell carcinoma (HSCC) is one of the malignant tumors with the worst prognosis in head and neck cancers. The transformation from normal tissue through low-grade and high-grade intraepithelial neoplasia to cancerous tissue in HSCC is typically viewed as a progressive pathological sequence typical of tumorigenesis. Nonetheless, the alterations in diverse cell clusters within the tissue microenvironment (TME) throughout tumorigenesis and their impact on the development of HSCC are yet to be fully understood. Methods: We employed single-cell RNA sequencing and TCR/BCR sequencing to sequence 60,854 cells from nine tissue samples representing different stages during the progression of HSCC. This allowed us to construct dynamic transcriptomic maps of cells in diverse TME across various disease stages, and experimentally validated the key molecules within it. Results: We delineated the heterogeneity among tumor cells, immune cells (including T cells, B cells, and myeloid cells), and stromal cells (such as fibroblasts and endothelial cells) during the tumorigenesis of HSCC. We uncovered the alterations in function and state of distinct cell clusters at different stages of tumor development and identified specific clusters closely associated with the tumorigenesis of HSCC. Consequently, we discovered molecules like MAGEA3 and MMP3, pivotal for the diagnosis and treatment of HSCC. Discussion: Our research sheds light on the dynamic alterations within the TME during the tumorigenesis of HSCC, which will help to understand its mechanism of canceration, identify early diagnostic markers, and discover new therapeutic targets.

Perioperative chemotherapy with docetaxel plus oxaliplatin and S-1 (DOS) versus oxaliplatin plus S-1 (SOX) for the treatment of locally advanced gastric or gastro-esophageal junction adenocarcinoma (MATCH): an open-label, randomized, phase 2 clinical trial.

BACKGROUND: It remains unclear whether addition of docetaxel to the combination of a platinum and fluoropyrimidine could provide more clinical benefits than doublet chemotherapies in the perioperative treatment for locally advanced gastric/gastro-esophageal junction (LAG/GEJ) cancer in Asia. In this randomized, phase 2 study, we assessed the efficacy and safety of perioperative docetaxel plus oxaliplatin and S-1 (DOS) versus oxaliplatin plus S-1 (SOX) in LAG/GEJ adenocarcinoma patients. METHODS: Patients with cT3-4 Nany M0 G/GEJ adenocarcinoma were randomized (1:1) to receive 4 cycles of preoperative DOS or SOX followed by D2 gastrectomy and another 4 cycles of postoperative chemotherapy. The primary endpoint was major pathological response (MPR). RESULTS: From Aug, 2015 to Dec, 2019,154 patients were enrolled and 147 patients included in final analysis, with a median age of 60 (26-73) years. DOS resulted in significantly higher MPR (25.4 vs. 11.8%, P = 0.04). R0 resection rate, the 3-year PFS and 3-year OS rates were 78.9 vs. 61.8% (P = 0.02), 52.3 vs. 35% (HR 0.667, 95% CI: 0.432-1.029, Log rank P = 0.07) and 57.5 vs. 49.2% (HR 0.685, 95% CI: 0.429-1.095, Log rank P = 0.11) in the DOS and SOX groups, respectively. Patients who acquired MPR experienced significantly better survival. DOS had similar tolerance to SOX. CONCLUSIONS: Perioperative DOS improved MPR significantly and tended to produce longer PFS compared to SOX in LAG/GEJ cancer in Asia, and might be considered as a preferred option for perioperative chemotherapy and worth further investigation.

Long-term outcomes of endoscopic or surgical resection in T1 colorectal cancer patients: a retrospective cohort study.

BACKGROUND: The personalized treatments of T1 colorectal cancer (CRC) remains controversial. We compared the long-term outcomes of T1 CRC patients after endoscopic resection (ER) and surgery, and evaluated the risk factors for the long-term prognosis. METHODS: T1 CRCs after resection at the Cancer Hospital, Chines Academy of Medical Sciences from June 2011 to November 2021 were reviewed. High-risk factors included positive resection margin, poor differentiation, deep submucosal invasion (DSI ≥ 1000 µm), lymphovascular invasion and intermediate/high tumor budding. Comparative analyses were conducted based on three treatment methods: follow-up after ER (Group A), additional surgery after ER (Group B) and initial surgery (Group C). The primary endpoints included recurrence-free survival (RFS) and overall survival (OS). Cox proportional hazard regression models were constructed to identify risk factors for RFS and OS. RESULTS: A total of 528 patients were enrolled (173 patients in Group A, 102 patients in Group B, 253 patients in Group C). The 3-year RFS, 5-year RFS, 3-year OS, and 5-year OS rates were 96.7%, 94.7%, 99.1%, and 97.8%, respectively. In the absence of other high-risk factors, RFS (P = 0.321) and OS (P = 0.155) of patients with DSI after ER were not inferior to those after surgery. Multivariate analyses identified sex (HR 0.379; 95% CI 0.160-0.894), Charlson comorbidities index (CCI) (HR 3.330; 95% CI 1.571-7.062), margin (HR 8.212; 95% CI 2.325-29.006), and budding (HR 3.794; 95% CI 1.686-8.541) as independent predictive factors of RFS, and identified CCI (HR 10.266; 95% CI 2.856-36.899) as an independent predictive factor of OS. CONCLUSION: The long-term outcomes of ER are comparable to those of surgery in T1 CRC patients with DSI when other high-risk factors are negative. Resection margin, tumor budding, sex, and CCI may be the most important long-term prognostic factors for T1 CRC patients.

A strategy combining endoscopic hand-suturing with clips for closure of rectal defects after endoscopic submucosal dissection with or without myectomy (with video).

BACKGROUND AND AIMS: Endoscopic hand-suturing (EHS) has been preliminarily demonstrated to be effective in closing defects after endoscopic submucosal dissection (ESD), but it is not easily performed. We proposed a strategy combining EHS with clips (EHS-Clips) and explored its effectiveness in closing rectal defects after ESD or ESD with myectomy (ESD-ME). METHODS: In this observational study, data from patients with rectal defects closed using EHS-Clips were reviewed. EHS-Clips refers to a strategy where defects are sutured as much as possible by EHS first, with clips being used to close the remaining parts of defects that cannot be completely sutured. The primary endpoints included complete closure rate, delayed bleeding (DB) rate, and sustained closure rate. Logistic regression analyses were performed to identify risk factors for the sustained closure. RESULTS: All 49 (100%) defects (42 ESD defects and 7 ESD-ME defects) were completely closed through the strategy of EHS-Clips, with 35 (71.4%) through EHS alone and 14 (28.6%) through EHS and additional clips. No patients experienced DB. Thirty-six (73.5%) defects remained sustained closure on postoperative days 3 to 5 (73.8% for ESD defects vs 71.4% for ESD-ME defects). The multivariate analyses identified a stitch margin of ≥5 mm (hazard ratio, 0.313; 95% confidence interval, 0.023-0.781; P = .009) as the only independent advantage factor for the sustained closure. CONCLUSIONS: EHS-Clips can be used to effectively close the rectal defects after ESD or ESD-ME and prevent DB. Complete suture with a stitch margin of ≥5 mm may achieve more reliable sustained closure.

Optimal starting age of endoscopic screening for esophageal cancer in China: A multicenter prospective cohort study.

BACKGROUND: Although endoscopic screening for esophageal cancer has been performed in high-risk areas in China for decades, there is limited and inconsistent evidence regarding the starting age for individuals participating in screening. The aim of this study is to investigate the optimal starting age of esophageal cancer screening. METHODS: This study is based on a multicenter prospective cohort consisting 338,017 permanent residents aged 40-69 years in six high-risk areas of esophageal cancer in China. The participation rate, detection rate, hazard ratios (HRs), cumulative incidence and mortality and number needed to screen (NNS) were calculated in each age group. Screening burden, benefit and risk were compared among screening strategies with different initiation ages to explore the optimal starting age for population-based screening in high-risk areas. RESULTS: Individuals aged 50-69 had a higher participation rate, a higher detection rate and improved screening effectiveness than those aged 40-49. The endoscopic screening had no significant effect on reducing the incidence of esophageal cancer in individuals under 55 and mortality in individuals under 45. Increasing the starting age to 50 years reduced the screening demand and NNS by 40% and 55%, and resulted in 12% of detectable positive cases, 16% of preventable incident cases, and 14% of preventable deaths being missed. CONCLUSIONS: Postponing the starting age of endoscopic screening to 50 years might yield a more-favorable balance between screening benefit and burden in high- risk areas with limited resources.

Radiotherapy Improves Survival of Patients With Lymphovascular Invasion in pT1b Esophageal Squamous Cell Cancer After Endoscopic Submucosal Dissection.

INTRODUCTION: Adjuvant radiotherapy is recommended for pT1b esophageal squamous cell cancer (ESCC) after endoscopic submucosal dissection (ESD). However, it is unclear whether additional radiotherapy can improve patient survival. This study aimed to evaluate the efficacy of adjuvant radiotherapy after ESD for pT1b ESCC. METHODS: This was a multicenter, cross-sectional study involving 11 hospitals in China. Between January 2010 and December 2019, patients with T1bN0M0 ESCC treated with or without adjuvant radiotherapy after ESD were included. Survival between groups was compared. RESULTS: Overall, 774 patients were screened, and 161 patients were included. Forty-seven patients (29.2%) received adjuvant radiotherapy after ESD (RT group) and 114 (70.8%) underwent ESD alone (non-RT group). There were no significant differences in overall survival (OS) and disease-free survival (DFS) between the RT and non-RT groups. Lymphovascular invasion (LVI) was the only prognostic factor. In the LVI+ group, adjuvant radiotherapy significantly improved survival (5-year OS: 91.7% vs 59.5%, P = 0.050; 5-year DFS: 92.9% vs 42.6%, P = 0.010). In the LVI- group, adjuvant radiotherapy did not improve survival (5-year OS: 83.5% vs 93.9%, P = 0.148; 5-year DFS: 84.2% vs 84.7%, P = 0.907). The standardized mortality ratios were 1.52 (95% confidence interval 0.04-8.45) in the LVI+ group with radiotherapy and 0.55 (95% confidence interval 0.15-1.42) in the LVI- group without radiotherapy. DISCUSSION: Adjuvant radiotherapy could improve survival in pT1b ESCC with LVI+ other than LVI- after ESD. Selective adjuvant radiotherapy based on LVI status achieved survival rates similar to those of the general population.

The Feasibility and Safety of Endoscopic Submucosal Dissection for Circumferential Superficial Esophageal Squamous Cell Neoplasms.

Background It remains controversial whether endoscopic submucosal dissection (ESD) is still appropriate for circumferential superficial esophageal squamous cell neoplasms (SESCN), and few studies compared the short-term and long-term outcomes of ESD with radical surgery. Methods A total of 140 patients with SESCN who underwent ESD or surgery between February 2014 and October 2021 were retrospectively reviewed. The characteristics of patients, operative time, postoperative complications, overall survival (OS), recurrence-free survival (RFS), and quality of life (QOL) were compared between the ESD and surgery groups. The effect of different methods to prevent esophageal stenosis after ESD were analysed. Results Drinking, family history of cancer, macroscopic type, and intrapapillary capillary loop (IPCL) type were independent risk factors for deep submucosal invasion (SM ≥ 200 µm). Smoking and IPCL type were independent predictive factors for angiolymphatic invasion. The average operative time of ESD was significantly shorter than that of surgery (174.5 ± 51.16 min vs. 255.9 ± 88.18 min, p < 0.001). The incidence of perioperative complications in ESD group was significantly lower than that in surgery group (5.5% vs. 19.4%, p = 0.015). The ESD group had significantly better functional scale scores for emotional functioning, cognitive functioning, and global health status, and lower rates of pain, dyspnoea, insomnia, appetite loss, diarrhoea, reflux, and trouble with taste than the surgery group. No significant difference in OS and RFS between ESD and surgery group. Conclusions ESD can significantly shorten the operative time and reduce perioperative complications. Additionally, on the premise of using appropriate measures to prevent postoperative stenosis, ESD can be the first choice for the treatment of SESCN, which could provide better QOL, and the long-term prognosis of ESD is no less than that of surgery.

Endoscopic therapy of anastomotic diverticulum combined with stercorolith incarceration: A case report.

Diverticulosis is a commonly acquired disease of the lower gastrointestinal tract, which may be associated with significant morbidity and adverse effects on quality of life. Although several national guidelines focused on the treatment of diverticulosis, multiple controversies remained regarding the disease management of diverticulosis. For some controversial issues, such as the role of antibiotics in mild diverticulitis, when and how to operate on patients with acute diverticulitis, there is no conclusion yet. To our knowledge, this is the first report of endoscopic therapy for anastomotic diverticulitis caused by stercorolith incarceration. In the current case, a 49-year-old woman complained of recurrent subumbilical pain without obvious inducement for half a year. Colonoscopy showed anastomotic diverticulum combined with stercorolith incarceration. After local inflammation relieved by conservative treatment, the patients received endoscopic mucosal incision and lithotomy. Then the diverticulum was closed with titanium clips. The abdominal pain of patient was completely relieved, and the reexamination of colonoscopy showed that the wound healed well after 1 year of follow-up. This case suggests that for anastomotic diverticulitis caused by stercorolith incarceration, endoscopic therapy can remove the stimulation factors better and avoid the recurrence and progression of the disease compared with conservative treatment. Moreover, endoscopic therapy achieves the maximum in minimally invasive surgery and reduces complications and surgical costs compared with radical surgery.

Comparison of Endoscopic Submucosal Dissection and Radical Surgery for Early Gastric Cancer in Remnant Stomach.

(1) Background: Endoscopic submucosal dissection (ESD) for early gastric cancer (EGC) in the remnant stomach or gastric tube is not yet widespread and few studies have compared the short-term and long-term outcomes with radical surgery. (2) Methods: A total of 73 consecutive patients with EGC in the remnant stomach or gastric tube who underwent ESD or radical surgery between October 2009 and October 2020 were retrospectively analyzed in this study. Baseline characteristics, post-operative complications, quality of life (QOL), recurrence rate, overall survival (OS) and disease-free survival (DFS) were compared between the ESD and surgery groups. (3) Results: Among the 73 patients with EGC in the remnant stomach or gastric tube, 48 (65.8%) underwent ESD and 25 (34.2%) underwent surgery. The operation time (p = 0.000) and post-operative hospital stay (p = 0.002) of the ESD group were significantly shorter than those in the surgery group. The incidence of post-operative complications in the ESD group was significantly lower than that in surgery group (p = 0.001). The ESD group had significantly better functional scale scores and lower rates of fatigue, pain, appetite loss, financial difficulties, dysphagia, eating restrictions, hair loss, and poor body image than the surgery group. There was no significant difference in OS or DFS between the ESD and surgery groups (p = 0.124 and 0.344, respectively). (4) Conclusion: ESD can significantly shorten the operation time and hospital stay, reduce surgical complications, and provide better QOL for patients with EGC in the remnant stomach or gastric tube, and its long-term prognosis is no shorter than that of radical surgery.

Endoscopic submucosal dissection for early esophageal squamous cell carcinoma with esophageal-gastric fundal varices caused by liver cirrhosis: a case report.

Background: There is limited reporting of treatment options for early esophageal squamous cell carcinoma in esophageal-gastric fundal varices patients. Historically, surgery is the preferred treatment for squamous cell carcinoma; however, esophagectomy is associated with higher complications and death rates. The difficulty of such an operation was the varicose veins around the mucosa of the lesion. Possibility of concomitant intraoperative fatal bleeding. Previous studies have proved the effectiveness of endoscopic mucosal resection (EMR) paired with endoscopic injection sclerotherapy (EIS) for treating early esophageal cancers on esophageal varices. Case Description: We reported an effective endoscopic treatment of such conditions in a 62-year-old man with liver cirrhosis. After seeking informed consent, we performed endoscopic submucosal dissection (ESD) of early esophageal squamous cell carcinoma after the eradication of esophageal-gastric fundal varices using EIS. The resection margins indicated negative for carcinoma and dysplasia, suggesting that no recurrence and complication occurred. The patient was discharged 5 days after ESD without any complications including perforation or bleeding. No complaint from the patient was received during the 1-week follow-up, and the patient was tolerating solid food. The pathological result of the two lesions both showed moderately differentiated squamous cell carcinoma of the esophagus, T1bN0M0. The resection margins suggested negative for both carcinoma and dysplasia according to pathological examination. There was no recurrence or adverse event during follow-up. Conclusions: Our case presented the successful treatment of esophageal squamous cell carcinoma on esophageal-gastric fundal varices. This indicated that patients with cirrhosis and portal hypertension could also be treated with ESD, which could reduce trauma and discomfort and improve their quality of life. We recommend future studies to further investigate the indications of using endoscopic treatment for patients with cirrhosis.

Solitary Rectal Ulcer Syndrome Is Not Always Ulcerated: A Case Report.

Solitary rectal ulcer syndrome (SRUS) is a benign and chronic disorder well known in young adults that is characterized by a series of symptoms such as rectal bleeding, copious mucus discharge, prolonged excessive straining, perineal and abdominal pain, a feeling of incomplete defecation, constipation and, rarely, rectal prolapse. The etiology of this syndrome remains obscure, and the diagnosis is easily confused with that of other diseases, contributing to difficulties in treatment. We present a case of a 37-year-old male with a nonulcerated rectal lesion grossly resembling a superficial depressed rectal cancer misdiagnosed in another hospital and describe its appearance on endoscopy and in the analysis of its pathological manifestations. The aim of this case report is to report an easily misdiagnosed case of SRUS, which needs to be distinguished from superficial rectal cancer, which should be educational for endoscopists.

Characteristics of bile microbiota in cholelithiasis, perihilar cholangiocarcinoma, distal cholangiocarcinoma, and pancreatic cancer.

Significant proof suggests an essential role played by the bile microbiota in biliary diseases. This study retrospectively analyzed the differences in biliary microbes among patients with perihilar cholangiocarcinoma (pCCA), distal cholangiocarcinoma (dCCA), pancreatic cancer (PC), and cholelithiasis (CH). Bile samples were obtained from 53 patients who underwent endoscopic retrograde cholangiopancreatography (ERCP), and the bile microbiota was analyzed through 16S rRNA gene analysis and next-generation sequencing. Based on the results of linear discriminant analysis effect size (LEfSe), the top three biomarkers for pCCA at the genus level were Pseudomonas, Sphingomonas, and Halomonas; for dCCA were Streptococcus, Prevotella, and Halomonas; and for PC were Pseudomonas, Chloroplast, and Acinetobacter. The top five genera in the pCCA, dCCA, and PC groups showed predictive values with areas under the receiver operating characteristic curves of 91.56%, 95.56%, and 96.59%, respectively. The PICRUSt2 analysis outcomes displayed the diversities of fifteen pathways between the CH and pCCA groups, 22 pathways between the CH and dCCA groups, and eighteen pathways between the CH and PC groups. As this pilot study identified specific microbial bile markers for patients with CH, pCCA, dCCA, and PC, the clinical implications are vast. Further study focusing on distinct bacterial populations in bile will help differentiate biliary diseases.

Preoperative Concurrent Chemoradiotherapy Versus Neoadjuvant Chemotherapy for Locally Advanced Gastric Cancer: Phase II Randomized Study.

Objective: We evaluated and compared the efficacy and safety of neoadjuvant chemoradiotherapy (NACRT) versus neoadjuvant chemotherapy (NACT) for locally advanced gastric cancer (LAGC) in a single-center randomized phase II trial. Methods: Patients with LAGC were enrolled and received either NACT or NACRT, followed by gastrectomy and adjuvant chemotherapy. The primary endpoint was an R0 resection rate. Results: We enrolled 75 patients: 75.7% (NACT, 28/37 patients) and 76.3% (NACRT, 29/38 patients) underwent surgery; R0 resection rates were 73.0% (27/37) and 73.7% (28/38), respectively. The NACRT group had significantly better major pathological response than the NACT group (37.9% vs 17.9%, p = 0.019). Between-group postoperative complications were not significantly different. The median follow-up was 59.6 months; 5-year overall survival (OS) rate was 50.1% (NACT) and 61.9% (NACRT); neither group reached the median OS; median progression-free survival was 37.3 and 63.4 months, respectively. Conclusions: S-1-based NACRT did not improve the R0 resection rate, although it presented better tumor regression with similar safety to NACT. Trial registration: ClinicalTrial.gov NCT02301481.

Combination of Endoscopic Resection and Radiofrequency Ablation for the Treatment of Esophageal Squamous Cell Neoplasia With Multiple Lugol-Voiding Lesions.

BACKGROUND: Local recurrence of esophageal squamous cell neoplasia (ESCN) and metachronous ESCN was associated with severe background esophageal multiple Lugol-voiding lesions (LVLs) even though the primary early ESCNs were treated with endoscopic resection (ER). The aim of this study is to explore the feasibility and effectiveness of combination treatments of ER and radiofrequency ablation (RFA) in patients with early ESCNs with synchronous multiple LVLs. METHODS: A total of 329 patients with early ESCNs and synchronous multiple LVLs received ER combined with RFA from September 2010 to September 2020. Clinical and pathological features and treatment outcomes were retrospectively reviewed using medical records. Factors associated with background esophageal multiple LVLs before combined treatment were analyzed. RESULTS: The proportion of complete response (CR) was 96.7% after primary RFA, while 90.3% patients achieved CR for the last endoscopic examinations regardless if inside or outside the treatment area (TA). Degeneration of background esophageal multiple LVLs occurred in 70.2% of patients. The grade of background esophageal multiple LVLs before combined treatment was closely related to gender, smoking, and drinking. The incidence of metachronous ESCNs outside the TA of ER and local recurrence in the TA of ER was 3.9% and 1.2%, respectively. CONCLUSIONS: Prophylactic RFA treatment of multiple LVLs together with ER treatment of the primary ESCNs may be effective in reducing the incidence of metachronous ESCNs and local recurrence through improving the background esophageal mucosa.

Characterization of the Oral and Esophageal Microbiota in Esophageal Precancerous Lesions and Squamous Cell Carcinoma.

Important evidence indicates that the microbiota plays a key role in esophageal squamous cell carcinoma (ESCC). Here, paired saliva and brush specimens were obtained from 276 participants undergoing upper gastrointestinal endoscopic examination before or during screening for upper gastrointestinal (UGI) cancer. The esophageal microbiota was investigated by 16S rRNA gene profiling and next-generation sequencing. We observed that as the disease progressed, the α diversity in the saliva and cell brush samples decreased. Linear discriminant analysis effect size (LEfSe) results showed that in both the saliva and cell brush specimens, Granulicatella, Rothia, Streptococcus, Gemella, Leptotrichia and Schaalia were common biomarkers in patients with low-grade dysplasia, Lactobacillus was a common biomarker in patients with high-grade dysplasia, and Bosea, Solobacterium, Gemella, and Peptostreptococcus were common biomarkers in patients with esophageal cancer. The top 3 genera in the saliva and cell brush specimens had areas under the curve (AUCs) of 87.16 and 89.13%, respectively, to distinguish ESCC patients from normal people. The PICRUSt2 results identified in brush samples that patients with ESCC had decreased nitrate reductase functions. Our results suggest that future studies can focus on the function of the characteristic bacteria in ESCC.

The effects of smoking and drinking on the oral and esophageal microbiota of healthy people.

BACKGROUND: To explore the effects of smoking and drinking on the microbiota in the saliva and three segments of the esophagus (upper, middle, and lower) in healthy individuals. METHODS: Paired saliva and brush specimens were obtained from 76 participants who underwent upper gastrointestinal (UGI) endoscopic examination for UGI cancer screening. The esophageal microbiota was investigated by 16S rRNA gene profiling via next-generation sequencing. RESULTS: The saliva samples from non-smoking and non-drinking participants had a greater abundance of Neisseria, Prevotella, Porphyromonas, and Rothia, and lower levels of Streptococcus, Actinobacillus, and Haemophilus compared to the esophagus. There were no significant differences in the abundance of most bacterial genera in the upper, middle, and lower oesophagus. Similarly, in the saliva of patients who smoke and drink, there was a higher prevalence of Neisseria, Prevotella, Porphyromonas, Fusobacterium, and Rothia, and a lower prevalence of Streptococcus, Actinobacillus, and Haemophilus compared to the esophagus. There were no significant differences in the abundance of most genera in the upper, middle, and lower esophagus of patients with a history of drinking and smoking. There were slight differences in the microbiota between smoking and drinking individuals and non-smoking and non-drinking individuals. CONCLUSIONS: This pilot study demonstrated microbial diversity at different taxonomic levels in the oral cavity and esophagus of non-drinking and non-smoking individuals, as well as healthy people who drink and smoke . There was a slight difference in the microbiota between non-drinking and non-smoking people and individuals with a history of drinking and smoking. These results suggested that oral or esophageal cancer caused by smoking and drinking may not be mediated by mechanisms that affect surface microorganisms.