Cholecystectomy and the risk of colorectal cancer

Risk of hepato-biliary cancer after cholecystectomy: a nationwide cohort study

BACKGROUND

Epidemiologic studies have identified cholecystectomy as a possible risk factor for cancers in Western countries. The aim of this study was to estimate the risk of hepato-biliary cancer after cholecystectomy in Taiwan.

METHODS

Based on the Taiwan National Health Insurance Research Database, 2,590 cholecystectomized patients without prior cancers in the period 1996-2008 were identified from a cohort dataset of 1,000,000 randomly sampled individuals. The standard incidence ratio (SIR) of each cancer was calculated.

RESULTS

After a median follow-up of 4.82 years, 67 liver cancer and 17 biliary tract cancer patients were diagnosed. Patients who received cholecystectomy had higher risks of liver cancer (SIR, 3.29) and biliary tract cancer (SIR, 8.50). Cholecystectomized patients aged ≤60 years had higher risks of liver cancer (SIR, 11.14) and biliary tract cancer (SIR, 55.86) compared to those aged >60 years (SIR, 2.31 and 5.67). Female cholecystectomized patients had higher risks of liver cancer (SIR, 4.18) and biliary tract cancer (SIR, 10.56) than males (SIR, 2.96 and 7.26). Cholecystectomized patients with cirrhosis had higher SIR of liver cancer than patients without cirrhosis (SIR, 33.84 vs. 1.41).

CONCLUSIONS

Cholecystectomy may be associated with an increased risk of hepato-biliary cancer. Further and regular surveillance should be performed on such patients.

Association between cholecystectomy and intestinal cancer: a national record linkage study

OBJECTIVE

To investigate the risk of intestinal cancer in a cohort of people who had undergone cholecystectomy for gallstones, and in a cohort of people who had been hospitalized for gallbladder disease but had not undergone cholecystectomy.

BACKGROUND

Some investigators have suggested that cholecystectomy increases the risk of intestinal cancer. Despite extensive study, the evidence remains inconclusive. If there is doubt about safety, the question arises of whether patients considering the operation should be told of a possible risk. It is also increasingly clear that there are noncausal associations between gallstones and intestinal cancer.

METHOD

Analysis of record-linked hospital admission and mortality statistics for England from 1998 to 2008; calculation of ratio of rates of cancers in the cholecystectomy cohort and the gallbladder disease cohort compared with a control cohort.

RESULTS

: In the first year after cholecystectomy, the rate ratios for cancer of the small intestine, colon, and rectum were significantly high at, respectively, 4.6 (95% confidence interval 3.9-5.5), 2.0 (1.9-2.1), and 1.7 (1.6-1.9). Rates of these cancers were also significantly high in people with gallstones without cholecystectomy. By 8 to 10 years after cholecystectomy, rate ratios had declined to nonsignificant levels.

CONCLUSIONS

These cancers are associated with gallstones. The highest elevation of risk of cancer after cholecystectomy was at the shortest time interval after operation. Thereafter, the level of risk in the cholecystectomy and control cohorts gradually converged. The association in this study, between cholecystectomy and intestinal cancer, is very unlikely to be causal. Intestinal cancers are, on occasion, initially misdiagnosed as gallbladder disease.

Increased cancer incidence in some gallstone diseases, and equivocal effect of cholecystectomy: a long-term analysis of cancer and mortality

BACKGROUND

Our aim was to investigate cancer incidence and the cause of long-term mortality in different gallstone diseases and conditions.

STUDY DESIGN

The study population consisted of 2034 subjects: 224 persons diagnosed with asymptomatic gallstones in 1983, 254 patients who underwent cholecystectomy in 1983, and 513 patients with symptomatic uncomplicated gallstones (SGS, n = 337) or acute cholecystitis (AC, n = 176) between 1992 and 1994. One thousand and forty-three people who participated in a population study in 1983 were controls.

RESULTS

An overall increased risk of cancer, as well as higher mortality, was found among persons with asymptomatic gallstones compared to controls (HR 1.46, 95% CI: 1.06-2.00 and HR 1.39, 95% CI: 1.08-1.78), whereas patients who underwent cholecystectomy in 1983 showed a slightly higher risk (not significant) for both cancer and death than controls. Among patients with SGS from 1992 to 1994 there was a significantly higher risk of contracting cancer in patients who had undergone surgery (HR = 2.56, 95% CI: 1.13-5.83). For patients with AC, there was no significant difference between surgically treated and non-surgically treated subjects, but there was a higher risk of cancer in all AC compared to SGS patients (HR 2.03, 95% CI: 1.20-3.43). Mortality did not differ significantly between surgically treated and non-surgically treated patients with SGS or AC.

CONCLUSION

Gallstone patients had a greater risk than the general population for developing cancer, but this was dependent on the type of gallstone condition and treatment. The effect of cholecystectomy seemed dubious.

New understandings about gallbladder function

The function of the gallbladder is to store and concentrate bile. Due to the high incidence of diseases such as gallstones, cholecystectomy has become one of the most common surgical procedures. Although cholecystectomy is a successful treatment for most patients, the loss of gallbladder function may contribute to chronic diarrhea and increase the incidence of proximal colon cancer, pancreatic cancer, hepatocellular carcinoma and esophageal adenocarcinoma. With the development of endoscopic technology and introduction of drugs that may prevent recurrence of gallstones, cholecystolithotomy with gall bladder preservation has become another choice for symptomatic gallstones, and it preserves the function of the gallbladder after the removal of gallstones. This may avoid the complications associated with the loss of gallbladder function.

History of cholelithiasis and cancer risk in a network of case-control studies

BACKGROUND

We analyzed the relationship between cholelithiasis and cancer risk in a network of case-control studies conducted in Italy and Switzerland in 1982-2009.

METHODS

The analyses included 1997 oropharyngeal, 917 esophageal, 999 gastric, 23 small intestinal, 3726 colorectal, 684 liver, 688 pancreatic, 1240 laryngeal, 6447 breast, 1458 endometrial, 2002 ovarian, 1582 prostate, 1125 renal cell, 741 bladder cancers, and 21 284 controls. The odds ratios (ORs) were estimated by multiple logistic regression models.

RESULTS

The ORs for subjects with history of cholelithiasis compared with those without were significantly elevated for small intestinal (OR=3.96), prostate (OR=1.36), and kidney cancers (OR=1.57). These positive associations were observed ≥10 years after diagnosis of cholelithiasis and were consistent across strata of age, sex, and body mass index. No relation was found with the other selected cancers. A meta-analysis including this and three other studies on the relation of cholelithiasis with small intestinal cancer gave a pooled relative risk of 2.35 [95% confidence interval (CI) 1.82-3.03].

CONCLUSION

In subjects with cholelithiasis, we showed an appreciably increased risk of small intestinal cancer and suggested a moderate increased risk of prostate and kidney cancers. We found no material association with the other cancers considered.

Gallstone disease in children

Gallstone disease in children is evolving, and for the previous 3 decades, the frequency for surgery has increased greatly. This is in part because of improved diagnostic modalities, but also changing pathology, an increased awareness of emerging comorbidities, such as childhood obesity, and other associated risk factors. This article outlines the pathophysiology, genetics, and predisposing factors for developing gallstones and includes a review of the literature on the current and more novel medical and surgical techniques to treat this interesting disease.

Gallstone disease is associated with rectal cancer: a meta-analysis

BACKGROUND

Increased levels of secondary bile acids after cholecystectomy and cholelithiasis are believed to increase the risk of colorectal cancer, and several studies have suggested that the risk of colorectal cancer may be the greatest proximally. Numerous conflicting studies have been published and it remains unclear whether the risk is apparent in the rectum. This meta-analysis aims to determine the risk of developing rectal cancer following gallstone disease or cholecystectomy.

METHODS

The prospective protocol included a literature search of PubMed, MEDLINE, EMBASE, and Current Contents (1950-2011). Selection criteria were developed to sort for studies exploring the relationship between cholelithiasis, cholecystectomy, and rectal cancer in an adult population. A random-effects model was used to generate pooled odds ratios (OR) and 95% confidence intervals (CI). Publication bias and heterogeneity were assessed.

RESULTS

Of the 2358 studies identified, 42 were suitable for final analysis. There were 1,547,506 subjects in total, 14,226 diagnosed with rectal cancer, and 496,552 with gallstones or cholecystectomy. There was a statistically significant risk of rectal cancer following cholelithiasis (OR = 1.33; 95% CI = 1.02-1.73), though no risk was apparent following cholecystectomy (OR = 1.14; 95% CI = 0.92-1.41).

CONCLUSIONS

Cholelithiasis increases the risk of rectal cancer. No association exists between cholecystectomy and rectal cancer.

Meta-analysis of observational studies on cholecystectomy and the risk of colorectal adenoma

AIM

Cholecystectomy has been suggested as a risk factor for colorectal cancer. However, the association of cholecystectomy and the risk of colorectal adenoma (CRA) remains unclear. We conducted a meta-analysis of observational studies to explore this relationship.

METHODS

We identified studies by a literature search of MEDLINE and EMBASE through 30 September 2011, and by searching the reference lists of pertinent articles. Summary relative risks (SRRs) with their 95% confidence intervals (CIs) were calculated with a random-effects model. Between-study heterogeneity was assessed using Cochran's Q statistic and the I2.

RESULTS

A total of 10 studies (including 4061 CRA cases) were included in this meta-analysis. Analysis of these 10 studies found that no effect of cholecystectomy on the risk of CRAs was shown (SRR, 1.17; 95% CI: 0.93-1.48), with no significant heterogeneity among these studies (P heterogeneity=0.106, I2=37.9%). This null association was seen in both men and women (men: SRR=1.00, 95% CI: 0.58-1.73; women: SRR=1.39, 95% CI: 0.95-2.04).

CONCLUSION

The results of this meta-analysis suggest that there is no positive association between previous cholecystectomy and the risk of CRA development in both men and women.

Use of metformin is not associated with a decreased risk of colorectal cancer: a case-control analysis

BACKGROUND

To explore the association between use of metformin or other antidiabetic drugs and the risk of colorectal cancer.

METHODS

Using the United Kingdom-based General Practice Research Database (GPRD), we conducted a nested case-control analysis in patients with diabetes mellitus. Cases had an incident diagnosis of colorectal cancer, and up to 6 controls per case were matched on age, sex, calendar time, general practice, and number of years of active history in the GPRD prior to the index date. Results were adjusted for multiple potential confounders.

RESULTS

We identified 920 diabetic patients with colorectal cancer. Mean age ± SD was 70.2 ± 8.6 years and 63.3% were male. Extensive use (≥50 prescriptions) of metformin was associated with a slightly increased risk of colorectal cancer (adjusted OR = 1.43, 95% CI: 1.08-1.90) as compared with non use, with an adjustment of OR = 1.81 (95% CI: 1.25-2.62) in men and of 1.00 (95% CI: 0.63-1.58) in women. Neither extensive use of sulfonylureas (adjusted OR = 0.79, 95% CI: 0.60-1.03) nor insulin (adjusted OR = 0.90, 95% CI: 0.63-1.28) were associated with an increased risk of colorectal cancer. A long-term history of diabetes (>10 years) was not associated with a materially increased risk of colorectal cancer compared with short-term diabetes duration (<2 years; adjusted OR = 1.14, 95% CI: 0.90-1.46).

CONCLUSION

Use of metformin was linked to an increased risk of colorectal cancer in men. Use of sulfonylureas or insulin was not associated with an altered risk of colorectal cancer.

IMPACT

Metformin does not prevent colorectal cancer.

Guidelines for the diagnosis and management of hereditary spherocytosis--2011 update

Guidelines on hereditary spherocytosis (HS) published in 2004 (Bolton-Maggs et al, 2004) are here replaced to reflect changes in current opinion on the surgical management, (particularly the indications for concomitant splenectomy with cholecystectomy in children with mild HS, and concomitant cholecystectomy with splenectomy in those with asymptomatic gallstones). Further potential long term hazards of splenectomy are now recognised. Advances have been made in our understanding of the biochemistry of the red cell membrane which underpins the choice of tests. Biochemical assays of membranes proteins and genetic analysis may be indicated (rarely) to diagnose atypical cases. The diagnostic value of the eosin-5-maleimide (EMA) binding test has been validated in a number of studies with understanding of its limitations.

Cholecystectomy and risk of pancreatic cancer: a meta-analysis of observational studies

OBJECTIVE

Data from epidemiological studies related to the association of cholecystectomy and pancreatic cancer (PaC) risk are inconsistent. We conducted a meta-analysis of observational studies to explore this relationship.

METHODS

We identified studies by a literature search of Medline (from 1 January 1966) and EMBASE (from 1 January 1974), through 30 June 2011, and by searching the reference lists of pertinent articles. Summary relative risks with their 95% confidence intervals were calculated with a random-effects model. Between-study heterogeneity was assessed using Cochran's Q statistic and the I (2).

RESULTS

A total of 18 studies (10 case-control studies, eight cohort studies) were included in this meta-analysis. Analysis of these 18 studies found that cholecystectomy was associated with a 23% excess risk of PaC (SRR = 1.23, 95% CI = 1.12-1.35), with moderate heterogeneity among these studies (p (heterogeneity) = 0.006, I (2) = 51.0%). Sub-grouped analyses revealed that the increased risk of PaC was independent of geographic location, gender, study design and confounders. There was no publication bias in the current meta-analysis.

CONCLUSIONS

The results of this meta-analysis suggest that individuals with a history of cholecystectomy may have an increased risk of pancreatic cancer.

Natural history of gallstone disease: Expectant management or active treatment? Results from a population-based cohort study

BACKGROUND AND AIMS

The knowledge of natural history is essential for disease management. We evaluated the natural history (e.g. frequency and characteristics of symptoms and clinical outcome) of gallstones (GS) in a population-based cohort study.

METHODS

A total of 11 229 subjects (6610 men, 4619 women, age-range: 29-69 years, mean age: 48 years) were studied. At ultrasonography, GS were present in 856 subjects (338 men, 455 women) (7.1%). GS were followed by means of a questionnaire inquiring about the characteristics of specific biliary symptoms.

RESULTS

At enrollment, 580 (73.1%) patients were asymptomatic, 94 (11.8%) had mild symptoms and 119 (15.1%) had severe symptoms. GS patients were followed up for a mean period of 8.7 years; 63 subjects (7.3%) were lost to follow up. At the end of the follow up, of the asymptomatic subjects, 453 (78.1%) remained asymptomatic; 61 (10.5%) developed mild symptoms and 66 (11.4%) developed severe symptoms. In subjects with mild symptoms, the symptoms disappeared in 55 (58.5%), became severe in 23 (24.5%), remained stable in 16 (17%); in subjects with severe symptoms, the symptoms disappeared in 62 (52.1%), became mild in 20 (16.8%) and remained stable in 37 (31.1%). A total of 189 cholecystectomies were performed: 41.3% on asymptomatic patients, 17.4% on patients with mild symptoms and 41.3% on patients with severe symptoms.

CONCLUSIONS

This study indicates that: (i) asymptomatic and symptomatic GS patients have a benign natural history; (ii) the majority of GS patients with severe or mild symptoms will no longer experience biliary pain; and (iii) a significant proportion of cholecystectomies are performed in asymptomatic patients. Expectant management still represents a valid therapeutic approach in the majority of patients.

Performance value of high risk factors in colorectal cancer screening in China

AIM: To analyze the performance value of high risk factors in population-based colorectal cancer (CRC) screening in China.

METHODS: We compared the performance value of the immunochemical fecal occult blood test (iFOBT) and other high risk factors questionnaire in a population sample of 13 214 community residents who completed both the iFOBT and questionnaire investigation. Patients with either a positive iFOBT and/or questionnaire were regarded as a high risk population and those eligible were asked to undergo colonoscopy.

RESULTS: The iFOBT had the highest positive predictive value and negative predictive value in screening for advanced neoplasia. The iFOBT had the highest sensitivity, lowest number of extra false positive results associated with the detection of one extra abnormality for screening advanced neoplasias and adenomas. A history of chronic cholecystitis or cholecystectomy, chronic appendicitis or appendectomy, and chronic diarrhea also had a higher sensitivity than a history of adenomatous polyps in screening for advanced neoplasias and adenomas. The sensitivity of a history of chronic cholecystitis or cholecystectomy was highest among the 10 high risk factors in screening for non-adenomatous polyps. A history of chronic appendicitis or appendectomy, chronic constipation, chronic diarrhea, mucous and bloody stool, CRC in first degree relatives, malignant tumor and a positive iFOBT also had higher sensitivities than a history of adenomas polyps in screening for non-adenomatous polyps. Except for a history of malignant tumor in screening for non-adenomatous polyps, the gain in sensitivity was associated with an increase in extra false positive results associated with the detection of one extra abnormality.

CONCLUSION: The iFOBT may be the best marker for screening for advanced neoplasias and adenomas. Some unique high risk factors may play an important role in CRC screening in China.

A previous cholecystectomy increases the risk of developing advanced adenomas of the colon

BACKGROUND

There is limited data assessing the relationship between cholecystectomy and colorectal adenomatous polyps (AP). Our aim was to determine if cholecystectomy was associated with an increased prevalence of advanced AP in male veterans.

METHODS

The relationship of whether prior cholecystectomy modified the natural history of AP was investigated in a retrospective study. The patients were divided into two groups: 1) those with AP and a history of cholecystectomy, and 2) those with AP, but without a history of cholecystectomy. Factors in each group associated with advanced AP were examined by univariate analysis (UA) and stepwise logistic regression analysis to determine independent predictors of aggressive clinical characteristics of polyps. Statistical significance was determined at a P < or = 0.05.

RESULTS

We identified a total of 1234 patients with AP (cases = 127, controls = 1107). The mean age of patients was 64.1 +/- 1.9 (standard deviation) years. By UA, those with a prior cholecystectomy had a greater mean number of AP (4.2 vs. 3.5; P = 0.04) and more advanced polyps (P = 0.037) than those without a cholecystectomy. By logistic regression, prior cholecystectomy was associated with more advanced AP (OR = 1.5 [1.0-2.2]; P = 0.04). Patients who had a cholecystectomy were 51% more likely to have advanced AP. There appeared to be a trend towards increased time from cholecystectomy being associated with advanced polyps (9.69 years vs. 8.99 years, P = 0.056).

CONCLUSIONS

A prior cholecystectomy was independently associated with an increased risk of developing advanced AP. Also, there appeared to be a trend toward a greater prevalence of advanced lesions as postcholecystectomy time increased.

Use of hormone replacement therapy and the risk of colorectal cancer

PURPOSE

Estrogen/progestin replacement therapy is prescribed to women in menopause for purposes of postmenopausal symptom control or prevention of hormone deficiency-related diseases such as osteoporosis. Such treatments have formerly been shown to be associated with lower colorectal cancer risk in an as yet unknown mechanism.

PATIENTS AND METHODS

The Molecular Epidemiology of Colorectal Cancer study was a population-based case-control study in northern Israel of patients with colorectal cancer who were diagnosed between 1998 and 2006, and age-, sex-, clinic-, and ethnicity-matched population controls. Use of hormone replacement therapy (HRT) was assessed using a structured interview and validated by studying prescription records in a subset of patients for whom they were available.

RESULTS

Two thousand four hundred sixty peri/postmenopausal women were studied from among 2,648 patients with colorectal cancer and 2,566 controls. The self-reported use of HRT was associated with a significantly reduced relative risk of colorectal cancer (odds ratio [OR], 0.67; 95% CI, 0.51 to 0.89). This association remained significant after adjustment for age, sex, use of aspirin and statins, sports activity, family history of colorectal cancer, ethnic group, and level of vegetable consumption (OR, 0.37; 95% CI, 0.22 to 0.62). Statistically significant interactions were seen between use of HRT and use of aspirin and involvement in sports activity. Using pharmacy data, only users of combined oral preparations demonstrated a significant negative association with colorectal cancer.

CONCLUSION

The use of oral HRT was associated with a 63% relative reduction in the risk of colorectal cancer in postmenopausal women after adjustment for other known risk factors. This effect was not found in aspirin users and women with intensive sports participation.

Cholelithiasis is a risk factor for colorectal adenoma

OBJECTIVES

Postcholecystectomy patients show moderate risk of colorectal cancer. However, few studies have investigated the relationship between cholelithiasis and colorectal adenoma. We examined this possibility through a combination of colonoscopy and ultrasonography in asymptomatic Japanese.

METHODS

We reviewed a subgroup of subjects drawn from a prospective annual colonoscopy screening survey. Subjects who underwent both ultrasonography and colonoscopy, and completed a questionnaire regarding lifestyle habits were entered. We investigated whether subjects with cholelithiasis or a previous cholecystectomy showed an increased risk of colorectal adenoma, as compared with subjects with normal gallbladders.

RESULTS

Data of 4,458 subjects (men 3,053, women 1,405, mean age +/- SD 46.1 +/- 8.62 yr) were analyzed. Cholelithiasis was detected in 206 subjects, 4,189 subjects had normal gallbladders, and 63 subjects had cholecystectomies. The prevalence of colorectal adenoma was 29.6% (61/206) in subjects with cholelithiasis, which was significantly higher when compared with normal subjects, with a prevalence of 17.7% (741/4,189, P < 0.001). In cholecystectomy patients, only 15.9% (10/63) developed colorectal adenomas, which was not significantly different from the control group. In a multivariate analysis controlling for sex, age, family history of colorectal cancer, alcohol, smoking, and body mass index, cholelithiasis was shown to be an independent risk factor for colorectal adenoma (adjusted OR 1.57, 95% CI 1.14-2.18). Cholelithiasis was strongly associated with multiple (> or = 3 lesions, adjusted OR 2.39, 95% CI 1.21-4.72) and left-sided colorectal adenomas (adjusted OR 1.82, 95% CI 1.28-2.59).

CONCLUSIONS

Cholelithiasis is a risk factor for colorectal adenoma.

Importance of postpolypectomy surveillance and postpolypectomy compliance to follow-up screening--review of literature

INTRODUCTION

Approximately 150,000 people are diagnosed with colorectal cancer each year and 56,000 may die from it annually in the United States. Colorectal cancer is the second leading cause of cancer deaths in the USA and yet, when diagnosed at an early stage, it is one of the most preventable cancers. According to the US Preventive Services Task Force, initial screening for colorectal cancer is recommended in people above 50 years of age with average risk and earlier in people with a strong family history and other risk factors. Adenomatous polyps are considered as precursors of colorectal cancer. Removal of polyps and postpolypectomy surveillance reduces the overall mortality from colorectal cancer.

DISCUSSION

According to updated guidelines in 2006, a 3-year-follow-up colonoscopy is recommended in patients with adenomatous polyps>or=1 cm. An important factor in the surveillance and prevention of colorectal cancer in postpolypectomy patients is compliance with follow-up colonoscopy. In the present article, we provide an overview of the importance of postpolypectomy surveillance and summarize the compliance data for postpolypectomy surveillance. Compliance to postpolypectomy surveillance varies from one study to another and it should be expected that the compliance with follow-up would be low outside of clinical trials. Some measures that can improve patient compliance include patient education regarding a need of follow-up screening, reminder letters, and alerts in patient's charts.

CONCLUSION

In conclusion, effective surveillance screening with good patient compliance in postpolypectomy patients will contribute significantly in reducing colon cancer morbidity and mortality.

Cholecystectomy and the risk of colorectal adenomas

Cholecystectomy has been identified as a risk factor for colorectal cancer, yet little attention has been given to the relationship between cholecystectomy and colorectal adenomas. Utilizing data collected in two large cross-sectional studies of colorectal adenoma risk factors, we examined the association between cholecystectomy and colorectal adenomas. In the adjusted logistic regression model, both men and women showed no effect of cholecystectomy on risk of colorectal adenomas (men: OR 0.67 [95% CI 0.30-1.47]; women: OR 1.46 [95% CI 0.92-2.29]). No effect was seen when examining the time since cholecystectomy for men. There was a slight association found for women who had a cholecystectomy less than 10 years prior (OR 2.02 [95% CI 1.06-3.87]) but no association was seen in women with cholecystectomy at least 10 years prior (OR 1.14 [95% CI 0.62-2.09]). Thus, we conclude that, although cholecystectomy is a risk factor for colorectal cancer, cholecystectomy is not a risk factor for colorectal adenomas.

The comparison of the risk factors and clinical manifestations of proximal and distal colorectal cancer

PURPOSE

Colorectal cancers in the proximal or distal site have distinct clinical characteristics. In this study, the authors compared the risk factors of proximal and distal colorectal cancer.

METHODS

A 16-page questionnaire was administered to 529 patients with colorectal cancer before operation. Cancers were classified as proximal or distal relative to the splenic flexure. Of these 529 patients, 6 patients were excluded because of the presence of synchronous colorectal cancers. Data of the 523 patients were analyzed.

RESULTS

Total numbers of proximal and distal cancers were 123 and 400. The proportion of patients with Type 2 diabetes was significantly higher for distal cancer (P = 0.034), whereas a greater proportion of patients with proximal cancer had a gallstone history (P = 0.005). Multivariate analysis revealed Type 2 diabetes to be a risk factor for distal colorectal cancer (P = 0.027) and cholelithiasis to be a risk factor for proximal cancer (P = 0.049). The odds ratio for distal colorectal cancer among males with Type 2 diabetes was 4.1 (95 percent confidence interval, 1.4-12.1). On the other hand, a gallstone history was more associated with proximal colon cancer, especially in females (odds ratio = 5.5; 95 percent confidence interval, 1.4-20.9).

CONCLUSIONS

A comparison of the risk factors of proximal and distal colorectal cancer showed that Type 2 diabetes is associated with distal colorectal cancer in males and that cholelithiasis is associated with proximal colon cancer in females.

Cholecystectomy and the risk of recurrent colorectal adenomas

Prior studies have shown an increased risk of colorectal cancer following cholecystectomy, but few studies have explored the association between cholecystectomy and the risk of colorectal adenomas. We used data from three large randomized adenoma chemoprevention trials to explore the association between cholecystectomy and the occurrence of adenomas. After adjusting for confounding factors, we found no increased risk for adenomas among individuals who had undergone cholecystectomy [risk ratio (RR), 1.02; 95% confidence interval (95% CI), 0.88-1.18]. There was a slight increase in the risk of advanced recurrent adenomas (RR, 1.28; 95% CI, 0.94-1.76) and multiple advanced recurrent adenomas (RR, 1.34; 95% CI, 0.97-1.85) but the 95% CIs included the null in both cases. We conclude that the increased risk for colorectal cancer following cholecystectomy seems to be due to a biological process occurring after the adenoma has developed.