A case-control study of risk factors for large bowel carcinoma

Chronic Constipation as a Risk Factor for Colorectal Cancer: Results From a Nationwide, Case-Control Study

BACKGROUND & AIMS

Prolonged colon transit times may increase the contact time between potential carcinogens in the stool and the colonic mucosa. Nonetheless, previous studies have yielded conflicting results connecting chronic constipation with the risk of colorectal cancer (CRC). We examined the association between chronic constipation and later CRC.

METHODS

In this nationwide case-control study, we identified 41,299 CRC cases by colorectal biopsy in Sweden between July 2007 and December 2016 and matched them to 203,181 age- and sex-matched controls from the general population. We compared odds of earlier chronic constipation (defined as ≥2 laxative prescriptions in the Prescribed Drug Register with ≥6 months between the first and last prescription) between CRC cases and controls using logistic regression. In separate analyses, we compared odds of earlier constipation between CRC cases and sibling comparators, but also examined earlier risk of having an inpatient/outpatient specialty diagnosis of chronic constipation before CRC.

RESULTS

Overall, 3943 patients with CRC met our criteria for chronic constipation before CRC. The crude proportion of chronic constipation in CRC patients was 9.5% compared with 8.8% in controls. After multivariable adjustment, there was a modest association between chronic constipation and later CRC (odds ratio [OR], 1.10; 95% CI, 1.06-1.14) that vanished using sibling comparators to control for residual confounding (OR, 1.04; 95% CI, 0.97-1.13). In a sensitivity analysis of 126,650 CRC patients diagnosed from 1989 to 2016, we found no association with earlier chronic constipation diagnosed in inpatient/outpatient specialty clinics (OR, 0.88; 95% CI, 0.75-1.04).

CONCLUSIONS

In a nationwide case-control study, chronic constipation was not associated with later CRC.

Long-term effects of appendectomy in humans: is it the optimal management of appendicitis?

INTRODUCTION

Appendectomy remains the gold standard for treating uncomplicated and complicated appendicitis. However, the vermiform appendix may play a significant role in the immune system (secondary immune function) and maintain a reservoir of the normal microbiome for the human body. The aim of this study was to summarize the long-term effects after appendectomy and discuss whether appendectomy is suitable for all appendicitis patients.

AREAS COVERED

A comprehensive and unbiased literature search was performed in PubMed. The terms 'appendix,' 'appendicitis,' 'appendectomy,' and 'endoscopic retrograde appendicitis therapy' were searched in the title and/or abstract. This review summarizes the long-term effects of appendectomy on some diseases in humans and describes three methods including appendectomy, medical treatment, and an 'organ-sparing' technique, named endoscopic retrograde appendicitis therapy (ERAT) to treat appendicitis.

EXPERT OPINION

Appendectomy remains the first-line therapy for appendicitis. The patient's problem is appendix, not appendicitis. If we treat appendicitis, the problem should be resolved. During COVID-19, an initial antibiotic treatment of mild appendicitis represents a promising strategy. For patients who are worried about the long-term adverse effect after appendectomy and have a strong desire to preserve the appendix and are aware of the risk of appendicitis recurrence, medical treatment, or ERAT could be proposed.

Impact of Appendectomy on Gut Microbiota

Background: Considered vestigial from the classic point of view, the vermiform appendix has long been the subject of intensive studies. The recent understanding of appendix function in the context of unique architecture and bacterial complexity and density allows considering it as a safehouse for intestinal biodiversity. Methods: This review analyzes and assesses the current state of scientific knowledge regarding the role of the vermiform appendix in normal gut microbiota maintenance as a crucial factor of host homeostasis. It also highlights the difference in microbial composition between the large bowel and the appendix, as well as the association between the surgical excision, appendectomy, and dysbiosis-induced diseases. In addition, the review discusses the results of epidemiologic studies on appendectomy as a risk factor for the initiation of gastrointestinal carcinogenesis. It also highlights the association between appendectomy and a series of chronic inflammatory and neurologic disorders, including inflammatory bowel disease.

Diet, obesity and colorectal carcinoma risk: results from a national cancer registry-based middle-eastern study

BACKGROUND

Cancer of colon and rectum (colorectal) is one of the most common cancers worldwide. There is a scarcity of published data on the risk factors for colorectal cancer (CRC) from the Middle-Eastern countries specifically in Kuwait. Therefore, this matched case-control study sought to examine the risk factors associated with CRC in Kuwait.

METHODS

One hundred and three histopathologically confirmed colorectal cancer cases were recruited from Kuwait Cancer Control Centre Registry. Two hundred and six controls matched with cases (2:1 ratio) on age, gender and nationality were selected from medical, ophthalmology, orthopedic and/ or surgical out-patient clinics at three main general hospitals in Kuwait. A structured questionnaire was used to collect the data from cases and controls through face-to-face interview. Adjusted matched odds ratios (mOR_adj) and their 95% confidence intervals (CI) were estimated using a multivariable conditional logistic regression model.

RESULTS

Multivariable conditional logistic regression model showed that cases were 4.3 times more likely to have had attainted obesity (BMI ≥ 30) in their lifetime compared to controls (mOR_adj = 4.3; 95% CI: 1.6-11.4). Compared to controls, cases rarely consumed fruits and vegetable (mOR_adj = 20.8; 95% CI: 4.4-99.5), tended to consume red meat 2-3 times a week (mOR_adj = 3.8; 95% CI: 1.6-8.7) or more than 4 times a week (mOR_adj = 9.4; 95% CI: 2.5-35.4). Reportedly cases compared to controls frequently (nearly every week) suffered from constipation (mOR_adj = 5.6; 95% CI: 1.9-16.5). However, CRC cases were less likely than controls to have been diagnosed in the past with hypercholesterolemia (mOR_adj = 0.3; 95% CI: 0.2-0.7) or diabetes mellitus type II (mOR_adj = 0.4; 95% CI: 0.2-0.8).

CONCLUSIONS

Obesity, excessive red meat consumption and infrequent fruits/vegetables intake were associated with an increased CRC risk. Overcoming identified pitfalls in dietary pattern and maintenance of healthy weight may help minimize CRC risk in Kuwait and perhaps other countries in the region. Further studies on genetic basis in conjunction with life styles and dietary factors may unravel their joint contributions to CRC risk and furnish tools for curtailing CRC risk in this and other similar populations.

Association between appendectomy and subsequent colorectal cancer development: an Asian population study

Objectives

The appendix may modulate colon microbiota and bowel inflammation. We investigated whether appendectomy alters colorectal cancer risk.

Methods

We identified a cohort of 75979 patients who underwent appendectomy between 1997 and 1999 based on the insurance claims of Taiwan. A comparison cohort of 303640 persons without appendectomy was selected randomly, frequency matched by age, sex, comorbidity and entry year was also selected. We monitored subsequent colorectal cancer development in both cohorts.

Results

The overall colorectal cancer incidence was 14% higher in the appendectomy patients than in the comparison cohort (p <0.05): the highest incidence was observed for rectal cancer, and the lowest incidence was observed for cancer of the cecum-ascending colon for both cohorts. Men were at higher risk than women. Subjects ≥ 60 years had an HR of 12.8 compared to those <60 years. The incidence of colorectal cancer was much higher in 1.5-3.5 years post appendectomy follow-up than for the comparisons (HR of 2.13). Patients who received an incidental appendectomy had an HR of 2.90 when compared to the comparisons.

Conclusions

Results of our study suggest that appendectomy in patients with appendicitis is likely associated with the development of colorectal cancer in the post-surgery period.

A prospective study of the effect of bowel movement frequency, constipation, and laxative use on colorectal cancer risk

OBJECTIVES

Constipation and laxative use have been hypothesized to increase colorectal cancer (CRC) risk, but existing epidemiologic studies have been inconclusive. To address this issue, the authors prospectively examined the association between CRC incidence and constipation, non-fiber laxative use, and fiber laxative use among 75,214 participants of the VITamins And Lifestyle study.

METHODS

Information on bowel movement frequency as well as average 10-year non-fiber laxative use, fiber laxative use, and constipation was ascertained by means of a questionnaire. Patients were followed from the time of receipt of the baseline questionnaire (2000-2002) until 2008 for CRC incidence, over which time 558 incident CRC cases occurred. Cox proportional hazard models were used to estimate the multivariate-adjusted hazard ratios (HRs) and 95% confidence intervals (95% CI).

RESULTS

Compared with individuals who used non-fiber laxatives less than once per year, the HRs associated with low (1-4 times per year) and high (≥5 times per year) use were 1.49 (95% CI: 1.04-2.14) and 1.43 (95% CI: 0.82-2.28), respectively (Ptrend=0.05). HRs for CRC were statistically significantly decreased and lowest in individuals who reported using fiber laxatives often (4+ days per week for 4+ years) vs. those who reported no use (HR=0.44; 95% CI: 0.21-0.95), although the trend was not significant (Ptrend=0.19). No statistically significant associations between bowel movement frequency or constipation and CRC risk were observed.

CONCLUSIONS

Findings from this study suggest that risk for CRC increases with non-fiber laxative use and decreases with fiber laxative use. However, further observational and experimental studies are needed to clarify these relationships before drawing conclusions about the preferred treatment of constipation.

Risk of developing colorectal cancer and benign colorectal neoplasm in patients with chronic constipation

BACKGROUND

Chronic constipation (CC) is a highly prevalent health problem, potentially associated with increased risk of colorectal cancer (CRCancer).

AIM

To investigate the association between CC, its severity, and CRCancer by estimating the relative risk of developing CRCancer and benign colorectal neoplasm (BCN) among severity-stratified patients with and without CC.

METHODS

Chronic constipation patients from a large retrospective US claims database were matched 1:3 with CC-free controls by demographic characteristics. CRCancer and BCN prevalence were measured over 1 year. In pre-index CRCancer- and BCN-free patients, incidence rate ratios (IRRs) of new CRCancer and BCN were calculated. Multivariate regression models adjusted for comorbidities and family history. CC patients' disease severity was rated based on CC-related resource use. IRRs for new CRCancer and BCN were estimated for CC severity groups and controls.

RESULTS

Chronic constipation (N = 28,854) and CC-free (N = 86,562) patients had mean age 61.9 years; 66.7% were female. One-year CRCancer prevalence was 2.7% and 1.7%, and BCN prevalence was 24.8% and 11.9% for CC and CC-free patients, respectively. Adjusted IRRs between CC and CC-free patients were 1.59 [95% confidence interval (CI): 1.43-1.78] and 2.60 [95% CI: 1.51-2.70] for CRCancer and BCN, respectively. Patients with severe and very severe CC had significantly greater incidence of CRCancer and BCN. At ≥ 2 and ≥ 5 years of observation, CRCancer and BCN incidence remained consistently and significantly higher for CC patients.

CONCLUSIONS

Patients with chronic constipation are associated with significantly higher prevalence and incidence of colorectal cancer and benign colorectal neoplasm than matched chronic constipation-free patients. These risks increase with the severity of chronic constipation.

Hay Fever and asthma as markers of atopic immune response and risk of colorectal cancer in three large cohort studies

BACKGROUND

In a previous analysis of 12 cancers in the Cancer Prevention Study II (CPS-II) cohort including follow-up from 1982-2000, having both hay fever and asthma was associated with lower colorectal cancer mortality. The combination of these allergic conditions may be a marker for allergy-related immune responses that could inhibit colorectal carcinogenesis.

METHODS

We examined the association of having both hay fever and asthma with colorectal cancer mortality among 1,023,191 participants in CPS-I, followed from 1959-1972, and 1,102,092 participants in CPS-II, now followed from 1982-2008. We also examined associations with colorectal cancer incidence among 174,917 participants in the CPS-II Nutrition Cohort, a subgroup of CPS-II followed from 1992-2007. During the follow-up, there were 5,644 colorectal cancer deaths in CPS-I, 13,558 colorectal cancer deaths in CPS-II, and 3,365 incident colorectal cancer cases in the CPS-II Nutrition Cohort. Cox proportional hazards regression was used to calculate multivariable-adjusted relative risks (RR) and 95% confidence intervals (CI).

RESULTS

RRs for colorectal cancer mortality associated with having both asthma and hay fever, compared with neither condition, were 0.90 (95% CI, 0.74-1.09) in CPS-I, 0.79 (95% CI, 0.69-0.91) in CPS-II, and 0.83 (95% CI, 0.74-0.92) when results from both cohorts were combined in a meta-analysis. The corresponding RR for colorectal cancer incidence in the CPS-II Nutrition Cohort was 0.90 (95% CI, 0.71-1.14).

CONCLUSION

These results support an association between having both hay fever and asthma and modestly lower colorectal cancer mortality.

IMPACT

Research examining other potential markers of allergy-related immune response in relation to colorectal cancer is warranted.

Diagnostic yield of colonoscopy for constipation as the sole indication

AIM

There is controversy over whether constipation as the only symptom should be an indication for routine diagnostic colonoscopy. The study was carried out to assess the prevalence of abnormal pathology on colonoscopy and to assess the risk factors for colonic neoplasia in patients with constipation but without 'high risk symptoms'.

METHOD

A cross-sectional, single-centre study was conducted on individuals who underwent colonoscopy for constipation as the sole indication between 2005 and 2008. Standardized endoscopic and pathology reports were reviewed. Univariable and multivariable analyses were performed.

RESULTS

A total of 786 patients (595 women, 75.7%; mean age, 57.4±13.5 years) underwent diagnostic colonoscopy for constipation. Forty-three (5.5%) had polyps, of whom 19 (2.4%) had hyperplastic polyps and 19 (2.4%) adenomas. No cancers were found. In patients with adenoma, the detection rate was 2.9% for patients below age 40 years and 1.7% for patients below age 50 years. Older age was associated with a polyp in both univariate and multivariate analysis. Gender, ethnicity and smoking were not associated with polyp or adenoma.

CONCLUSION

Colonoscopy for patients with constipation as the sole indication had a lower yield of neoplastic lesions than that for patients undergoing routine screening colonoscopy. Colonoscopy in constipation may only be warranted in patients who are over 50 years of age.

Most bowel cancer symptoms do not indicate colorectal cancer and polyps: a systematic review

BACKGROUND

Bowel symptoms are often considered an indication to perform colonoscopy to identify or rule out colorectal cancer or precancerous polyps. Investigation of bowel symptoms for this purpose is recommended by numerous clinical guidelines. However, the evidence for this practice is unclear. The objective of this study is to systematically review the evidence about the association between bowel symptoms and colorectal cancer or polyps.

METHODS

We searched the literature extensively up to December 2008, using MEDLINE and EMBASE and following references. For inclusion in the review, papers from cross sectional, case control and cohort studies had to provide a 2×2 table of symptoms by diagnosis (colorectal cancer or polyps) or sufficient data from which that table could be constructed. The search procedure, quality appraisal, and data extraction was done twice, with disagreements resolved with another reviewer. Summary ROC analysis was used to assess the diagnostic performance of symptoms to detect colorectal cancer and polyps.

RESULTS

Colorectal cancer was associated with rectal bleeding (AUC 0.66; LR+ 1.9; LR- 0.7) and weight loss (AUC 0.67, LR+ 2.5, LR- 0.9). Neither of these symptoms was associated with the presence of polyps. There was no significant association of colorectal cancer or polyps with change in bowel habit, constipation, diarrhoea or abdominal pain. Neither the clinical setting (primary or specialist care) nor study type was associated with accuracy.Most studies had methodological flaws. There was no consistency in the way symptoms were elicited or interpreted in the studies.

CONCLUSIONS

Current evidence suggests that the common practice of performing colonoscopies to identify cancers in people with bowel symptoms is warranted only for rectal bleeding and the general symptom of weight loss. Bodies preparing guidelines for clinicians and consumers to improve early detection of colorectal cancer need to take into account the limited value of symptoms.

Missed cancerous lesions in emergency laparoscopic surgery: retrospective study of 2074 cases

Abdominal laparoscopy is a widely accepted surgical procedure effective even for acute abdominal ailments. However, one major concern in using abdominal laparoscopy is missed lesions, in the past this has not been adequately explored. The aim of this retrospective study, therefore, is to evaluate cancerous lesions that are missed during emergency laparoscopic surgeries. The medical records of 2074 patients who had a laparoscopy from March 1996 to April 2006 for acute abdomen symptoms, including diagnostic laparoscopy (n = 119), laparoscopic appendectomy (n = 1336), laparoscopic duodenorrhaphy (n = 30), and laparoscopic cholecystectomy (n = 589) were reviewed. Missed cancerous lesions included cecal cancer (n = 2), sigmoid cancer (n = 1), and jejunum lymphoma (n = 1). The incidence of missed cancerous lesions in an emergency laparoscopic surgery is 0.19%, mainly due to its lower tactile sensitivity compared to the direct hand palpation and masqueraded by inflammatory process. Therefore, careful observation is recommended for post-emergency laparoscopic patients and follow-up should be performed within three months, especially for patients with intra-abdominal and/or severe inflammation status.

Impact of functional gastrointestinal disorders on survival in the community

OBJECTIVES

Functional gastrointestinal disorders (FGIDs) comprise a constellation of symptoms that have no identifiable structural or biochemical abnormality. In view of the lack of data from large-scale population-based studies evaluating the effects of these disorders on survival, we aimed to examine whether FGIDs are associated with impaired survival.

METHODS

Between 1988 and 1993, valid self-report questionnaires that recorded gastrointestinal symptoms required for the diagnosis of irritable bowel syndrome (IBS), chronic constipation, chronic diarrhea, dyspepsia, and abdominal pain were mailed to randomly selected cohorts of Olmsted County, Minnesota residents. Minnesota administrative death records were used to identify which of the survey respondents had died over the follow-up period (through April 2008). The association between survival and each FGID was assessed using proportional hazards regression models with univariate and adjusted hazard ratios (HRs, 95% confidence intervals (CIs)), adjusting for age at time of survey, gender, smoking, alcohol, marital status, and Charlson Comorbidity Index (CCI).

RESULTS

Of the 5,262 randomly selected eligible subjects who received a questionnaire, a total of 4,176 responded to the surveys (overall response rate 79%). From these respondents, 243 subjects were excluded because of lack of research authorization (or were registered solely at a different medical institution in Olmsted County, MN), resulting in 3,933 eligible subjects for analysis (eligible response rate 75%); 10% reported symptoms of IBS; 16% chronic constipation; 18% chronic diarrhea; 2% dyspepsia; and 15% abdominal pain. At baseline, the mean (s.d.) age was 54 (18) years, and 52% were female. No association with overall survival was detected for IBS (HR=1.06 (95% CI: 0.86-1.32)), chronic diarrhea (HR=1.03 (95% CI: 0.90-1.19)), abdominal pain (HR=1.09 (95% CI: 0.92-1.30)), or dyspepsia (HR=1.08 (95% CI: 0.58-2.02)). Reporting symptoms of chronic constipation was associated with poorer survival (HR=1.23 (95% CI: 1.07-1.42)). This association remained significant after adjusting for the CCI (HR=1.19 (95% CI: 1.03-1.37)).

CONCLUSIONS

In this large population-based cohort study with over 30,000 person-years of follow-up, no significant association was observed between survival and IBS, chronic diarrhea, dyspepsia, or abdominal pain. Furthermore, no association was found between increasing burden of FGIDs and survival. However, in contrast to these other FGIDs, subjects with symptoms of chronic constipation were found to be at increased risk of poorer survival. Further investigation is required to determine the cause of this observed association.

A prospective cohort study of rectal cancer risk in relation to active cigarette smoking and passive smoke exposure

PURPOSE

The present investigation prospectively examined active cigarette smoking and household passive smoke exposure and the risk of developing rectal cancer.

METHODS

Cigarette smoking data were collected on all household members during two private censuses in Washington County, Maryland. These two cohorts were followed up, one cohort from 1963-1978 and the other from 1975-1994 for first-time diagnoses of rectal cancer. We identified 148 and 169 rectal cancer cases in the 1963 and 1975 cohorts, respectively. Relative risks were estimated by means of Poisson regression models.

RESULTS

In men, the adjusted relative risks (aRR) and 95% confidence intervals (CI) for the association between current smoking and rectal cancer were 3.1 (1.2-7.8) in the 1963 cohort and 1.8 (0.9-3.7) in the 1975 cohort; the corresponding aRRs in women were 0.9 (0.5-1.8) and 1.6 (0.9-3.8) in the 1963 and 1975 cohorts, respectively. In nonsmokers, household passive smoke exposure was strongly associated with rectal cancer among men in the 1963 cohort (aRR = 5.8; 1.8-18.4) but not the 1975 cohort (aRR = 1.1; 0.2-5.0). In women, household passive exposure was not strongly associated with rectal cancer in either cohort.

CONCLUSIONS

The results of our study suggest that active cigarette smoking may contribute to rectal cancer risk, but inconsistencies in the findings preclude drawing strong, clear-cut inferences.

Incidence and odds ratio of appendicitis as first manifestation of colon cancer: a retrospective analysis of 1873 patients

BACKGROUND AND AIM

Obstruction of the lumen of the appendix is the major cause of appendicitis. Tumors could obstruct this lumen and cause appendicitis in the elderly. The association between appendicitis and colon cancer has not been sufficiently investigated, and this study was designed to clarify this association.

METHODS

This was a retrospective study. Patients diagnosed with acute appendicitis from January 1998 to December 2003 at the Taipei Veterans General Hospital were surveyed. Patients found to have colon cancers immediately or subsequently after appendectomy were included and analyzed.

RESULTS

A total of 1873 patients were diagnosed as having appendicitis of whom 16 were found to have colon cancer. The incidence of appendicitis associated with colon cancer was 0.85%. The time from appendectomy to the recognition of colonic cancer was at a median delay of 5.8 months. From the Taiwan Cancer Research Annual Report, the incidence of colon cancer was 31.91/100,000 in the year 2000. The odds ratio of colon cancer incidence had a 38.5-fold increase among patients older than 40 with acute appendicitis.

CONCLUSIONS

In patients over 40 years who present with symptoms of acute appendicitis the possibility of a coexistent colonic neoplasm should always be kept in mind. These patients should undergo colonoscopy 6 weeks after surgery to exclude the possibility of a coexistent colorectal cancer.

Colorectal cancer incidence among female textile workers in Shanghai, China: a case-cohort analysis of occupational exposures

Previous studies have suggested increased risks of colorectal cancers among textile industry workers, potentially related to synthetic fibers. To investigate risks of colon and rectum cancers in relation to these and other textile industry exposures, we conducted a case-cohort study nested within a cohort study of female employees from the Shanghai Textile Industry Bureau (STIB). Cox proportional hazard regression modeling was used to estimate hazard ratios (HR) for colon and rectum cancers associated with duration of employment (e.g., 0, >0 to <10, 10 to <20 years, > or =20 years) in various jobs classified according to process type and exposures to specific agents. Our findings indicate that certain long term exposures may pose increased risk of colorectal cancers, especially dyes and dye intermediates with colon cancer (> or =20 years exposure versus never, HR=3.9; 95% CI: 1.4-10.6), and maintenance occupation (HR = 2.3; 95% CI: 1.0-5.7) and metals exposure (HR = 2.0; 95% CI: 1.1-3.6) with rectum cancer. A decreased risk of rectum cancer was associated with exposure to natural fibers such as cotton (HR = 0.7; 95% CI: 0.5-0.9), and a trend of decreasing rectum cancer incidence was observed by category of cumulative quantitative cotton dust or endotoxin exposures, when exposures were lagged by 20 years.

Constipation, laxative use and risk of colorectal cancer: The Miyagi Cohort Study

The objective of this study was to investigate the association between constipation or laxative use and the risk of colorectal cancer in Japanese men and women. In 1990, we delivered a self-administered questionnaire to 41670 subjects who were 40-64 years old. During the seven years of follow-up, 251 incident cases of colorectal cancer were documented. Constipation was defined as a bowel movement frequency of less than daily. The multivariate relative risk (RR) of colorectal cancer for constipated subjects compared with those with daily bowel movements was 1.35 (95% Confidence Interval: 0.99-1.84). The RR for laxative users over non-users was 1.31 (0.88-1.95), and for frequent users (twice a week or more) it was 2.75 (1.48-5.09). When colorectal cancers were divided into colon cancers or rectal cancers, a significant association was found with colon cancer alone. Our results support the hypothesis that constipation or laxative use increases the risk of colon cancer.

Allergy and the risk of selected digestive and laryngeal neoplasms

The relation between allergy and cancer has been investigated within an integrated series of case-control studies of digestive tract and laryngeal neoplasms conducted in Italy since the early 1990s. These included 598 patients with incident, histologically confirmed cancer of the oral cavity and pharynx, 304 of the oesophagus, 1225 of the colon, 728 of the rectum, 460 of the larynx and 4999 controls, selected among patients admitted to the same network of hospitals as cases for acute, non-neoplastic diseases. Inverse associations with history of allergy were found for all cancer sites examined (odds ratio=0.44 for oral cavity and pharynx, 0.80 for oesophagus, 0.76 for colon, 0.54 for rectum and 0.33 for larynx). The associations were consistent in strata of age and sex, and when subjects with a first diagnosis of allergy 5 or more years before cancer diagnosis or hospital admission were considered. The present study therefore provides further evidence for a possible protective effect of prior history of allergy on cancer risk.

Appendectomy during childhood and adolescence and the subsequent risk of cancer in Sweden

OBJECTIVE

Researchers have speculated that surgical excision of lymphoid tissue, such as appendectomy, early in life might confer an increased risk of cancer. In this study, we determined the risks of cancer for people who had appendectomy performed during childhood.

METHODS

We studied the risk of cancer in a large Swedish cohort of children who had appendectomy performed during the period of 1965-1993. Standardized incidence ratios (SIRs) were computed using age-, gender-, and period-specific incidence rates derived from the entire Swedish population as comparison. Hospital discharge diagnosis data were used to examine cancer risks by categories of surgery, medical conditions, and type of appendicitis. The average length of follow-up was 11.2 years.

RESULTS

We found no excess overall cancer risk but noted a significant excess for stomach cancer (SIR: 2.45; 95% confidence interval [CI]: 1.1-4.8) and a borderline increase of non-Hodgkin's lymphoma (NHL; SIR: 1.55; 95% CI: 1.0-2.3). The elevated risks for both cancers were only evident 15 or more years after appendectomy (stomach cancer, SIR: 3.82; 95% CI: 1.7-7.5; NHL, SIR: 2.49; 95% CI: 1.4-4.2).

CONCLUSIONS

It is reassuring that there was no overall increase of cancer several years after childhood appendectomy. Increased risks for NHL and stomach cancer, occurring 15 or more years after appendectomy, were based on small absolute numbers of excess cancers. As 95% of the subjects were younger than 40 years at exit, this cohort requires continuing follow-up and monitoring.

Constipation, laxative use, and colon cancer in a North Carolina population

OBJECTIVE

The aim of this study was to determine whether bowel movement frequency and laxative use and type were associated with risk of colon cancer in white and black men and women.

METHODS

We conducted a population-based, case-control study with equal representation by blacks. Eligible subjects between ages 40 and 80 yr residing in urban and rural communities in North Carolina were asked about bowel habits and laxatives during face-to-face interviews. There were 643 cases (349 white, 294 black) and 1048 controls (611 white, 437 black).

RESULTS

Constipation, defined as fewer than three reported bowel movements per wk, was associated with a greater than two-fold risk of colon cancer (OR 2.36; 95% CI = 1.41-3.93) adjusted for age, race, sex, and relevant confounders. The association was greater for women (OR 2.69; 95% CI = 1.46-4.94) than for men (OR 1.73; 95% CI = 0.61-4.88) and stronger in blacks than whites. Black women had the highest risk (OR 3.42; 95% CI = 1.60-7.34), which remained significant (OR 3.21; 95% CI = 1.46-7.04) even after excluding subjects with late stage (distant) disease. The OR for constipation was slightly higher for distal than for proximal colon cancers. There was no association with laxative use (OR 0.88; 95% CI = 0.69-1.11). Fiber commercial laxatives appeared to exert a protective effect in a small subgroup.

CONCLUSIONS

This study provides support for a positive association between constipation and increased risk for colon cancer. Women, especially black women with constipation, seem to be at the highest risk.

Primary prevention of colorectal cancer: diet and drugs

Primary prevention of colonic adenomas and cancer through dietary interventions or chemoprevention has great appeal. This article discusses primary prevention goals and promising nutritional or chemopreventive strategies. There is substantial observational evidence that diets high in total calories and fat and or low in fruits and vegetables or total fiber as well as low levels of physical activity are related to the risk of colonic neoplasia. Similar observational data indicate that diets high in specific nutrients such as antioxidant vitamins or calcium may be protective. The article describes some of the newer chemopreventive agents and reviews the data linking diet and lifestyle to colorectal cancer risk, focusing on interventions that have also been studied in prospective clinical trials. Finally the evidence supporting the role of non-steroidal anti-inflammatory drugs for the chemoprevention of CRC is reviewed and the status of several other promising newer agents that are entering human trials is summarized.

Epidemiologic evidence of cancer risk in textile industry workers: a review and update

A meta-analysis of epidemiologic studies for textile industry workers was undertaken in an attempt to evaluate whether the cancer risk varies within the textile industry in relation to the job held or the textile fiber used. We combined studies published up until 1990, when an ad hoc IARC Monograph was issued, and those published after 1990 with the aim of appreciating evidence of reversing trends in cancer risk. Observed and expected cases reported in the original studies were summed up and the totals were divided to obtain a pooled relative risk (PRR) with a 95% confidence interval (CI) estimated with a fixed-effect model. We calculated a chi-square test (chi2) of heterogeneity among studies. When PRR and chi2 were both significant, PRR and CI were calculated with a random-effect model and the source of heterogeneity was investigated. Lung cancer risk was around 0.4 in the first study on cotton workers published in 1936, around 0.7 in subsequent studies, mostly published in the 1970s and 1980s, and around 1.0 in the last studies published in the 1990s. Papers published in the 1970s and 1980s produced consistent risk estimates for lung cancer risk, which was significantly lower than 1.0 in workers exposed to cotton (PRR = 0.77; CI = 0.69-0.86) and wool dust (0.71; 0.50-0.92), as well as in carders and fiber preparers (0.73; 0.54-0.91), weavers (0.71; 0.56-0.85), and spinners and weavers (0.78; 0.66-0.91). Lung cancer PRRs did not significantly deviate from 1.0 in textile workers using synthetic fibers or silk, and in dyers. Increased PRRs were found for sinonasal cancer in workers exposed to cotton dust, and in workers involved in spinning or weaving (4.14; 1.80-6.49). PRR was 1.46 (1.10-1.82) for cancer of the digestive system in textile workers using synthetic fibers or silk, and 1.34 (1.10-1.59) for colorectal cancer in spinners and weavers. The increased bladder cancer PRR in dyers (1.39; 1.07-1.71) is generally attributed to textile dye exposure. In studies published after 1990, there is a general tendency to move toward unity for all the cancer risk estimates, leading to an increasing heterogeneity among studies. Since adjustment for smoking made little difference to the findings, the latter could be attributed to the exposure to textile dusts. The recent findings could be due to a lowering of dust concentration in the workplaces. The reduction of cases of upper respiratory tract cancer parallels with a corresponding increase of lung cancer cases. So, preventive measures have paradoxically increased the lung cancer burden to the textile workers.

Cancer and benign tumor incidence among employees in a polymers research complex

The detection of several intracranial tumors among employees in one building complex (C500) at a petrochemical research facility prompted investigation of a possible workplace cause. This retrospective follow-up study included 1847 subjects, of whom 1735 had worked in C500. Medical records, death certificates, and Illinois State Cancer Registry data confirmed self-reported cancers and tumors. Analyses compared the subjects' cancer and benign intracranial tumor incidence rates with national general population rates. C500 employees had 15% fewer than expected total cancers (92 observed/108 expected; standardized incidence ratio [SIR], 85; 95% confidence interval [95% CI], 69 to 104). An excess of brain cancer (6/2.0; SIR, 302; 95% CI, 111 to 657) was concentrated among white men who had 10 or more years since hire and 5 or more years of C500 employment (4/0.7; SIR, 602; 95% CI, 165 to 1552) and who had worked in a particular building of C500 (5/0.7; SIR, 735; 95% CI, 239 to 1716). An excess of benign intracranial tumors (6/1.6; SIR, 385; 95% CI, 142 to 839) was not restricted to a single type of tumor and was not concentrated in any particular building. Occupational exposure may have caused the increased rate of brain cancer but is a less likely explanation for the elevated rate of benign intracranial tumors.

Cancer incidence among employees at a petrochemical research facility

This investigation evaluated cancer incidence among workers at a petrochemical research facility in Illinois. A cluster of brain cancer and other intracranial tumors had occurred at the facility before the study began. The subjects were 5641 people who had worked at the facility from 1970 through 1996 and who had lived in Illinois at any time between 1986 and 1997. Data on cancer cases came primarily from the Illinois State Cancer Registry. Analyses compared the 1986-to-1997 cancer incidence rates of employees with Illinois general population rates. Subjects had 18% fewer than expected total cancers (125 observed/153 expected cases; standardized incidence ratio [SIR], 82; 95% confidence interval [CI], 68 to 98), which was primarily attributed to a large deficit of lung cancer (10/26; SIR, 39; CI, 19 to 72). Brain cancer was increased in the overall study group (6/2.7; SIR, 222; CI, 81 to 484). This excess was restricted to white men who were scientists or technicians for one of the three companies at the facility (6/0.8; SIR, 750; CI, 275 to 1633); all cases in this group had worked in the "500 building complex" (6/0.6; SIR, 968; CI, 355 to 2106). Subjects also had an increased incidence of thyroid cancer (7/2.6; SIR, 265; CI, 106 to 546) that was not concentrated in particular occupational or building groups. The brain cancer incidence patterns indicated that an unidentified occupational exposure might have been responsible for the excess. Chance, socioeconomic factors leading to better case detection in facility employees than in the general population, and confounding by potential nonoccupational risk factors are plausible explanations of the observed increase in thyroid cancer.

Mortality among employees at a petrochemical research facility

BACKGROUND

This retrospective follow-up study evaluated mortality during 1970-1996 among 6,956 employees at a petrochemical research facility in Illinois.

METHODS

Standardized mortality ratios (SMRs) compared employees' mortality rates with those of the Illinois general population. Poisson regression procedures estimated rate ratios for various subject subgroups compared to other facility employees.

RESULTS

Subjects had 267 observed/524 expected deaths (SMR = 51) from all causes combined and a large deficit of deaths from all cancers (76/136, SMR = 56) and from most other major diseases. Other results included fewer than expected brain cancers (1/4.0, SMR = 25) and a slight increase in colorectal cancer (20/14, SMR = 139) that was concentrated in white male scientists employed for one of the three main companies at the facility (SMR = 295, RR = 2.6).

CONCLUSIONS

The deficit of brain cancer deaths contrasts with an excess incidence seen in a companion study. Subjects' generally favorable mortality experience probably reflects socioeconomic advantages of employees relative to the Illinois general population.

Allergy and other selected diseases and risk of colorectal cancer

It has been reported that allergy and other diseases may be related to colorectal cancer risk. The aim of this study was to perform a systematic analysis using information about medical histories specifically to see if there was any relation between allergies or other medical conditions and colorectal cancer risk. A multicentric case-control study was conducted in six Italian areas between 1992 and 1996 on 1225 incident cases of colon cancer, 728 cases of rectal cancer and 4154 controls comparable with cases according to sex and age group, admitted for acute conditions to the same network of hospitals where cases had been identified. Unconditional logistic regression models including terms for sex, age, study centre, years of education, body mass index, physical activity, smoking, history of colorectal cancer in first-degree relatives and energy intake were used to estimate the odds ratios (OR) of colon and rectal cancer according to history of allergy and other selected diseases. The OR for history of allergy was 0.88 (95% confidence interval, CI, 0.67-1.14) for colon and 0.64 (95% CI, 0.44-0.92) for rectal cancer, and the inverse association was stronger when allergy was diagnosed at age 35 years or more, or less than 10 years before the cancer diagnosis. No clear pattern emerged in strata of age and sex. History of other selected diseases, including hypertension and cholelithiasis, was not related to colon or rectal cancer risk, though there was a moderate increase in the risk of colon cancer (OR = 1.18, 95% CI, 0.66-2.14) in patients with a history of intestinal polyps. This study lends support to the hypothesis that allergic individuals may be at a lower risk of developing colorectal cancer.

The relationship between smoking exposure and p53 overexpression in colorectal cancer

Although epidemiological studies of the relationship between cigarette smoking and colorectal cancer risk have been equivocal, a positive association is consistently found for colorectal adenoma development. We performed an epidemiological study to determine whether p53 protein overexpression, in tumours obtained at the time of resection, is associated with cigarette exposure in colorectal cancer. A total of 163 colorectal cancer cases and 326 healthy controls responded to a standardised questionnaire on colorectal cancer risk factors including detailed information on their history of cigarette smoking. All patients' tumours were analysed immunohistochemically for p53 overexpression using an avidin-biotin immunoperoxidase procedure and polyclonal anti-p53 antibody CM1. Comparison of colorectal cases with controls revealed an elevated risk for ex-smokers (OR = 1.34, 95% CI 0.85-2.12) and current smokers (OR = 1.13, 95% CI 0.63-2.02) when compared with non-smokers. No dose-response relationship was found for total pack-years of smoking (trend test: P = 0.19). However, a trend for total pack-years of smoking was found when p53-positive cases were compared with p53-negative cases suggesting aetiological, heterogeneity (trend test: P = 0.06). Estimating the individual relative risk of developing a p53-positive tumour relative to controls showed no associations for smoking status or total pack-years of smoking. However, when p53-negative cases were compared with controls, an elevated risk was found for ex-smokers (OR = 1.84, 95% CI 1.00-3.37) and current years of smoking (trend test: P = 0.03). Colorectal tumours developing through p53-positive dependent pathways were not associated with smoking exposure. A significant increase in risk was observed for the p53-negative independent pathway with smoking. p53 overexpression appears to be associated with smoking exposure in colorectal cancer.

Cholecystectomy as a risk factor for colorectal cancer: a meta-analysis

BACKGROUND

It has been suggested that there is an increased risk of colorectal cancer after cholecystectomy due to increased levels of secondary bile acids. Some studies suggest the risk is higher for women and for the development of right-sided tumours.

METHODS

A review of the literature yielded 95 relevant studies, of which 35 were suitable for a meta-analysis involving age- and sex-matched controls.

RESULTS

The pooled odds ratio for a positive association between cholecystectomy and colorectal cancer was 1.11 (95% confidence interval (CI), 1.02 to 1.21). For women the odds ratio was 1.14 (95 % CI, 10.01 to 1.28) and for right-sided cancer 1.86 (95% CI, 1.31 to 2.65).

CONCLUSIONS

It is possible that this small observed association may be due to a publication bias for positive results or bias within the included studies. If it is indeed a real effect, the risk to an individual is very small.

Increased risk of colorectal cancer among smokers: results of a 26-year follow-up of US veterans and a review

To clarify the relationship between tobacco use and risk of colorectal cancer, we evaluated a cohort of 248,046 American veterans followed prospectively for 26 years. In comparison with veterans who had never used tobacco, the risk of death was significantly increased for colon cancer and rectal cancer among current and former cigarette smokers and among pipe or cigar smokers, controlling for social class and occupational physical activity. Rectal-cancer risk was also significantly elevated among users of chewing tobacco or snuff. For both sites, risk increased significantly with pack-years, earlier age at first use, and number of cigarettes. These results reinforce 2 recent reports of the association of cigarette smoking and colorectal cancer in men and women. Inconsistencies in the findings of earlier epidemiologic studies appear to be due in large part to differences in length of follow-up or in choice of controls. Studies with at least 20 years of follow-up or population-based controls have tended to find elevated risk with tobacco smoking, while those with shorter follow-up or hospital controls have not. This, plus the strength and consistency of the association of smoking and colon polyps, suggest that smoking may primarily affect an early stage in the development of colon cancer. If this association is causal, tobacco use may be responsible for 16% of colon-cancer and 22% of rectal-cancer deaths among these veterans.

Retrospective cohort study of workers of a synthetic textiles plant in Quebec: II. Colorectal cancer mortality and incidence

This paper describes standard mortality and nested case-control analyses of colorectal cancer for a cohort of synthetic textiles workers in which a cluster of five cases was observed previously. The cohort consisted of 7,487 men and 2,724 women who had more than 1 year's experience at the plant and who were either working in 1947 or were newly employed between 1947 and 1977. The Standardized Mortality Ratio (SMR) for colorectal cancer for men was 0.69 (95% confidence interval (CI): 0.52-0.92; 50 deaths) and for women it was 1.02 (95% CI: 0.57-1.69; 15 deaths). Among men only there was a suggestion that risks increased according to the length of service at the plant. In the nested case-control study, incident cases as well as deceased cases were included. A variety of analyses were carried out according to duration of employment in the processing units. For men the risk of colon cancer increased with duration of employment in the polypropylene and cellulose triacetate extrusion unit (unadjusted odds ratio (OR) for > or = 5 years duration = 5.52; 95% CI: 1.12-27.26; 4 exposed cases). It was not possible, however, to provide an independent confirmation of this putative association because the case series included three of the original five cases. There was some evidence of increased risks in the cellulose acetate fiber manufacturing unit and in the dyeing and finishing unit, but the data were compatible with the null hypothesis of no effect. No associations were observed for employment in any of the other processing units.

Retrospective cohort study of workers of a synthetic textiles plant in Quebec: I. General mortality

This paper presents results from a retrospective cohort study of workers of a synthetic textiles plant in Quebec. This plant has been the subject of a previous case-control study, in which an excess risk of colorectal cancer was observed. The cohort consisted of 7,487 men and 2,724 women who had worked at least 1 year at the plant and who were either working in 1947 or were newly employed between 1947 and 1977. The period of follow-up was from 1947 to 1986, thus yielding 307,278 person-years of observation. Mortality rates for most causes of death were less than expected; the standardized mortality ratio (SMR) for all causes of death among men was 0.73 (95% confidence interval (CI): 0.70-0.77) and among women it was 0.77 (95% CI: 0.68-0.87). For men, the SMR for all neoplasms was 0.76 (95% CI: 0.69-0.83) and for colorectal cancer it was 0.69 (95% CI: 0.52-0.92). For women, the SMR for all neoplasms was 1.01 (95% CI: 0.83-1.22) and for colorectal cancer it was 1.02 (95% CI: 0.57-1.69). Among men, risks for ischemic heart disease increased with increasing length of service at the plant, even though the SMRs were less than unity (overall SMR = 0.76; 95% CI: 0.70-0.83); no trend was observed for women. SMRs and relative risks were also calculated according to duration of employment in each processing unit. Of the scores of associations tested, very few showed increased risks. Of those showing increased risks, the data were not persuasive in indicating a connection with work at the plant; nevertheless, some of these associations may be worth following up in future studies. The following associations of potential significance were observed: all cancers, liver and gallbladder cancers, non-Hodgkin's lymphomas, and reticulum cell sarcoma in the cellulose acetate fiber manufacturing unit; all cancers in the polypropylene and cellulose triacetate extrusion unit and in the janitor unit; leukemias in the unexposed unit; ischemic heart disease in the maintenance and janitor units; and cerebrovascular disease in the weaving unit.

Cholecystectomy and colorectal cancer in China

Colorectal cancer is a major public health problem in China: 79,800 new cases are estimated to occur each year, which ranks it among the five most common tumours in China. Although the association between cholecystectomy and colorectal cancer has been studied elsewhere, few studies have been conducted in the Chinese population, characterized by a lower fat intake, and low colorectal cancer incidence. We conducted this hospital-based case-control study to explore this association. The study included a total of 503 incident cases with pathologically diagnosed colorectal cancer in Drum Tower Hospital at Nanjing in China from 1965 to 1986, and 2188 healthy controls who had annual routine physical examinations at the same hospital. Diagnosis of cholelithiasis was confirmed by ultrasonography or X-ray cholecystography, and the information on cholecystectomy was obtained by checking medical charts for both cases and controls. The prevalence of cholelithiases was 5.8% for cases and 6.1% for controls (P > 0.05). Eight cases (1.6%) and 18 controls (0.8%) had a history of previous cholecystectomy. The period between cases' cholecystectomy and diagnosis of colorectal cancer ranged from 2.5 to 23 years, and the mean interval was 8.9 years. The crude odds ratio for patients having previous cholecystectomy is 1.95 (95% CI: 0.84-4.51) compared with controls. The odds ratio for female patients with previous cholecystectomy was 2.79 (95% CI: 1.03-7.59). When subsites were analysed, a significant association between right colon cancer and cholecystectomy was noted: the odds ratio was 6.2 (95% CI: 2.24-16.9), and that for females was even higher 8.61 (95% CI: 2.44-3.04) with statistical significance.(ABSTRACT TRUNCATED AT 250 WORDS)

A meta-analysis of cholecystectomy and risk of colorectal cancer

BACKGROUND

Over 60 studies have addressed the hypothesis that the risk of colorectal cancer is increased following cholecystectomy; these studies have yielded inconsistent findings. The aim of the present study was to quantitatively summarize the results from the collective studies.

METHODS

A meta-analysis of the published studies addressing the relation between cholecystectomy and colorectal cancer was conducted.

RESULTS

The combined results from 33 case-control studies showed an association between cholecystectomy and risk of colorectal cancer (pooled relative risk [RR] = 1.34; 95% confidence interval [CI] = 1.14-1.57), particularly when limited to the proximal colon (RR = 1.88; 95% CI = 1.54-2.30). In most studies, the risk was stronger when the first 5-15 years following the surgery were excluded. The results from 6 cohort studies, with follow-up to approximately 15 years postcholecystectomy, were generally null (RR = 0.97; 95% CI = 0.82-1.14). A more limited body of evidence suggests that cholelithiasis is related to an elevated risk of proximal colon cancer.

CONCLUSIONS

Because the risks varied substantially by study design and because time since cholecystectomy or potentially confounding factors were often not considered, we could not firmly quantitate this risk. However, the findings are consistent with other evidence that suggests some characteristic of bile acid metabolism increases the risk of cancer of the proximal colon.

Smoking and colorectal cancer risk: data from the Melbourne Colorectal Cancer Study and brief review of literature

Lifetime smoking data were obtained from 715 colorectal cancer cases and 727 age/sex matched community controls as one part of a large, comprehensive, population-based study of colorectal cancer aetiology and survival in Melbourne, Australia, The Melbourne Colorectal Cancer Study. Statistically significant associations were found for those males smoking handrolled cigarettes and for cigar-/pipe-smoking males with colon cancer. Review of 18 previous case control studies of colorectal cancer showed an elevated risk for cigar-smoking black males in one study, a statistically non-significant increased risk for current smokers in one of 3 cohort studies and a statistically significant elevation of risk for smokers in 2 of 3 studies of adenomatous large-bowel polyps. Although at present there is insufficient evidence to link smoking with large-bowel cancer, the possibility that ingested tobacco is in some way carcinogenic for the colorectal mucosa may be worth further study.

Gallstones and colorectal cancer--there is a relationship, but it is hardly due to cholecystectomy

The prevalence of gallstone disease in 145 consecutive patients with colorectal cancer was compared with gallstone prevalence in 4,159 subjects randomly selected from a population. The group of patients had a significantly higher prevalence of gallstone disease than the population (odds ratio = 1.59; 95 percent confidence limits 1.04-2.45), whereas cholecystectomies occurred with equal frequency in the two groups. There was a nonsignificant trend toward more right-sided cancers in patients with gallstones than in patients without. These results, together with available literature, give substantial evidence for an association between gallstones and colorectal cancer, an association which is not due to cholecystectomy being a predisposing factor to colorectal cancer. Sporadic findings of an association between cholecystectomy and colorectal cancer can be explained by the above relationship.

Alcohol consumption and the etiology of colorectal cancer: a review of the scientific evidence from 1957 to 1991

The relationship between alcohol consumption and colorectal cancer in humans has been examined in 52 major studies in the past 35 years. An association was found in five of the seven correlational studies. An elevated risk was found in about half of the 31 case-control studies and, of these, in 9 of the 10 studies using community controls but in only 5 of the 17 studies using hospital controls (p = 0.008), suggesting that the absence of association when hospital controls are used is due to a high prevalence of alcohol consumption/alcohol-related illness in the hospital controls. Of the 14 cohort studies, an association with alcohol was found in 10, while in 3 of the 4 cohort studies in which an association was not found the alcohol data obtained were somewhat restricted. A positive dose-response effect was found in two of three cohort studies and in all four case-control studies with community controls in which this effect was examined. In both case-control and cohort studies, the association was found for females and males and for colon and rectal cancer. When the type of alcohol consumed was examined separately, beer was the principal type of at-risk alcoholic beverage, with much less risk for spirits and least risk for wine. Statistically significant elevations of risk were more often found in males than in females and slightly more frequently for rectal than for colon cancer and were related almost entirely to beer, rather than to wine or spirit, consumption. The alcohol risk was independent of the dietary risk in those studies that controlled for this factor. There was some confirmatory evidence for alcohol augmentation in rodent models of chemically induced carcinogenesis in six of nine studies. The hypotheses of alcohol as a direct and specific colorectal carcinogen include increased mucosal cell proliferation, the activation of intestinal procarcinogens, and the role of unabsorbed carcinogens, particularly in beer. Also, five of six other human studies showed an association between alcohol/beer consumption and adenomatous polyps, consistent with the hypothesis that alcohol stimulates the colorectal mucosa. General or indirect carcinogenic effects of alcohol include immunodepression, activation of liver procarcinogens, and changes in bile composition, as well as nitrosamine content of alcoholic beverages and increased tissue nitrosamine levels. With alcohol/beer consumption, the overall conclusion on present evidence is that alcohol, particularly beer consumption, is an etiologic factor for colon and rectal cancer for females and males.(ABSTRACT TRUNCATED AT 400 WORDS)

Cholecystectomy as a risk factor for colorectal adenomatous polyps and carcinoma

Multiple studies have suggested a possible relationship between prior cholecystectomy and the occurrence of subsequent colorectal carcinoma. This relationship has been particularly noticed among female patients and for right-sided lesions of the colon. In the current study, the authors undertook a case-control study among patients who underwent colonoscopy in three private practices in New York City between April 1986 and March 1988. Over this period, 302 adenomatous polyp cases, 106 colon cancer cases, and 507 controls were interviewed regarding their prior history of cholecystectomy. Overall, no significant association was observed between cholecystectomy and either colorectal adenomatous polyps or cancer. Cholecystectomy does not appear to be a significant risk factor for colorectal neoplasia.

Cholecystectomy and right colon cancer in Puerto Rico

A case-control study was undertaken to evaluate the possible relationship between cholecystectomy and right colon cancer. Two hundred patients with adenocarcinoma of the cecum or ascending colon (diagnosed between 1984 and 1989) were compared with 200 matched neighborhood controls. Cholecystectomy history was obtained through interviews using structured questionnaires and subsequently validated from hospital records. A statistically significant association (odds ratio = 2.14) was found between right colon cancer and a history of prior cholecystectomy. The altered bile metabolism which occurs after removal of the gallbladder may have a carcinogenic effect on the right colon. Dietary habits of the colon cancer patients in our study were consistent with prior reports in the literature, showing that this group has a lower intake of vegetables and cereal fiber than the control population.

Industrial risk factors for colorectal cancer

Colorectal cancer is the second most common malignancy in the United States, and its incidence rates have sharply increased recently, especially in males. Industrial exposures, both occupational and environmental, are important colorectal cancer risk factors that are generally unrecognized by clinicians. Migration studies have documented that colorectal cancer is strongly associated with environmental risk factors. The causal role of occupational exposures is evidenced by a substantial literature associating specific work practices with increased colorectal cancer risks. Industrially related environmental exposures, including polluted drinking water and ionizing radiation, have also been associated with excess risks. Currently, there is a tendency to attribute colorectal cancer, largely or exclusively, to dietary and other lifestyle factors, thus neglecting these industrially related effects. Concerted efforts are needed to recognize the causal role of industrial risk factors and to encourage government and industry to reduce carcinogenic exposures. Furthermore, cost-effective screening programs for high-risk population groups are critically needed to further reduce deaths from colorectal cancer.

Duodenogastric reflux of bile acids, gastrin and parietal cells, and gastric acid secretion before and 6 months after cholecystectomy

In order to evaluate the effect of cholecystectomy on the gastric mucosa, the duodenogastric reflux of total and single bile acids, the number of parietal and gastrin cells, and the volume of gastric acid secretion were examined in 15 patients with gallstones and functioning gallbladders before and 6 months after cholecystectomy. The duodenogastric reflux of the total bile acids increased from a mean preoperative value of 1.9 mumol/hour to a mean postoperative value of 21 mumol/hour (p = 0.008). The duodenogastric reflux of all single bile acids increased after cholecystectomy, with a higher increase in glycoconjugated compared with tauroconjugated bile acids. The parietal cells decreased from a mean preoperative value of 82.8 to a mean postoperative value of 68.7 (p = 0.05), whereas there was only a mild increase in the number of gastrin cells; the output of gastric acid remained unchanged. The variation of the gastrin cells before and after cholecystectomy was negatively correlated only with the variation of taurocholic acid (r = -0.50, p = 0.05), while the variation of the parietal cells was mildly correlated with all single bile acids (r = 0.35-0.50, 0.05 less than p less than 0.02). These findings show an increased duodenogastric reflux of bile acids 6 months after cholecystectomy with a mild morphologic alteration of the gastric mucosa.

The reliability of routine pathologic diagnosis of colorectal adenocarcinoma

The diagnosis of colorectal adenocarcinoma is generally considered as being reliable. However, the reproducibility of the classification of specific histologic patterns and the interrater agreement on the gradings have not been firmly established. A panel of three independent expert pathologists reviewed histologic sections from 128 patients selected among 1848 with colorectal cancer, diagnosed in 11 hospitals of the same region. The panel agreed with 92.6% of the original diagnoses of colorectal adenocarcinoma. As for agreement between panel members, the kappa value was 0.78 for the diagnosis of adenocarcinoma and 0.62 for confirmation of colorectal origin. The intraclass correlation coefficient for tumor differentiation features was 0.75. The proportion of villous and adenomatous components also generated good agreement. However, the grading of mucin secretion showed poor agreement (intraclass correlation coefficient = 0.44). Results confirm the reliability of routine pathological diagnosis and also demonstrate the reproducibility of basic diagnostic categories and pathognomonic features. Thus, to obtain reliable information from medical records for epidemiologic and clinical studies, data should be limited to well-defined diagnostic and histopathologic categories.

Cholecystectomy and colorectal cancer

This review examines the evidence for and against an association between cholecystectomy and colorectal cancer.

Large bowel cancer after cholecystectomy

In a large, population-based case control study of colorectal cancer, 65 of 715 patients and 57 of 727 control subjects had a previous cholecystectomy (chi-square = 0.6, relative risk 1.18, 95 percent confidence interval 0.81 to 1.70, p = 0.45). There was no statistically significant association between previous cholecystectomy and the risk of colorectal cancer, colon cancer, right colon cancer, any of the subsites of colon cancer, rectal cancer, age, or sex. Although there is some evidence from other studies of an association between previous cholecystectomy and right colon cancer in women, this may have resulted from confounding symptoms. Based on the present evidence, we believe that previous cholecystectomy is unlikely to be a risk factor for colorectal cancer.