THE APPENDIX IN RELATION TO NEOPLASTIC DISEASE

Risk of colorectal cancer after appendectomy: A systematic review and meta-analysis

BACKGROUND AND AIM

Appendectomy is associated with various diseases, but whether it increases the risk of colorectal cancer (CRC) remains uncertain. We conducted a systematic review and meta-analysis aimed at investigating the suggested correlation between appendectomy and CRC.

METHODS

Systematic retrieval was performed using the PubMed, Embase, Cochrane library, Web of Science, and ClinicalTrials.gov databases up to May 4, 2022, for studies reported the influence of appendectomy on CRC, colon cancer (CC) or rectal cancer (RC). Odd ratios (ORs) and 95% confidence intervals (CIs) of CRC after appendectomy were pooled using the random effects model. Subgroup analyses were carried on by region, sex, and tumor location.

RESULTS

Our search identified 1743 articles, of which 22 studies from three continents published between 1964 and 2022 were eligible for inclusion. Overall, people with appendectomy had a higher risk of CRC (OR = 1.31; 95% CI [1.05, 1.62]). But the risk for Europeans was not significant (OR = 0.94; 95% CI [0.87, 1.02]; I²  = 0%), while for Americans and Asians, appendectomy would increase the risk of CRC (OR = 1.68; 95% CI [1.15, 2.44]; I²  = 65% and OR = 1.46; 95% CI [1.04, 2.05]; I²  = 98%), especially in females and in developing countries. It is worth noting that appendectomy might be a protective factor for CC in European women (OR = 0.87; 95% CI [0.77, 0.98]; I²  = 0%).

CONCLUSIONS

Appendectomy may be a risk factor for CRC, with varying degrees in different populations. More high-quality cross-regional studies are needed for better clinical decision making.

Altered gut microbiome composition by appendectomy contributes to colorectal cancer

Appendectomy impacts the homeostasis of gut microbiome in patients. We aimed to study the role of appendectomy in colorectal cancer (CRC) risk through causing gut microbial dysbiosis. Population-based longitudinal study (cohort 1, n = 129,155) showed a 73.0% increase in CRC risk among appendectomy cases throughout 20 years follow-up (Adjusted sub-distribution hazard ratio (SHR) 1.73, 95% CI 1.49-2.01, P < 0.001). Shotgun metagenomic sequencing was performed on fecal samples from cohort 2 (n = 314). Gut microbial dysbiosis in appendectomy subjects was observed with significant enrichment of 7 CRC-promoting bacteria (Bacteroides vulgatus, Bacteroides fragilis, Veillonella dispar, Prevotella ruminicola, Prevotella fucsa, Prevotella dentalis, Prevotella denticola) and depletion of 5 beneficial commensals (Blautia sp YL58, Enterococcus hirae, Lachnospiraceae bacterium Choco86, Collinsella aerofaciens, Blautia sp SC05B48). Microbial network analysis showed increased correlation strengths among enriched bacteria and their enriched oncogenic pathways in appendectomy subjects compared to controls. Of which, B. fragilis was the centrality in the network of the enriched bacteria. We further confirmed that appendectomy promoted colorectal tumorigenesis in mice by causing gut microbial dysbiosis and impaired intestinal barrier function. Collectively, this study revealed appendectomy-induced microbial dysbiosis characterized by enriched CRC-promoting bacteria and depleted beneficial commensals, signifying that the gut microbiome may play a crucial role in CRC development induced by appendectomy.

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.

Evaluating the distribution of the locations of colorectal cancer after appendectomy and cholecystectomy

Backgrounds

The number of appendectomies and cholecystectomies performed is gradually increasing worldwide. An increasing incidence of colorectal cancer (CRC) after appendectomy and cholecystectomy has been reported, but the location of tumors in certain segments of the colon and rectum after appendectomy and cholecystectomy is still uncertain. We aimed to evaluate the distribution of the locations of colorectal cancer after appendectomy and/or cholecystectomy in patients who underwent CRC surgery.

Methods

We reviewed the medical records of patients who had undergone CRC surgery between 2015 and 2017 for the presence of previous appendectomy/cholecystectomy. Data were collected from the Colorectal Data Base of the University of Szeged, Department of Surgery.

Results

Surgery for CRC was performed in 640 patients during the study period. Data of 604 patients were analyzed. Appendectomy was performed in 100 patients (16.6%), cholecystectomy in 65 (10.8%), and both interventions in 18 (3%) before the CRC surgery. Out of those patients who underwent appendectomy alone, 92 (92%) had undergone appendectomy more than 10 years before the CRC surgery. Also in these 100 patients, the prevalence of right-sided colon cancer (CC) was 35% (n = 35), in comparison with the prevalence among the 504 other patients (20.4%, n = 103). The prevalence of right-sided CC among patients who underwent cholecystectomy alone was 36.9% (n = 24), in comparison with 21.2% (n = 114) of the 539 other patients.

Conclusions

A significant left to right side shift in CRC was noted among patients who had previously undergone appendectomy/cholecystectomy. Because right-sided CC has a worse prognosis, the role of incidental appendectomy and routine cholecystectomy seems that need re-evaluation.

Risk of lymphoid neoplasms in a Swedish population-based cohort of 337,437 patients undergoing appendectomy

OBJECTIVE

Appendectomy remains one of the most common surgical procedures, but possible long-term consequences for health and disease are incompletely investigated. The appendix forms part of the secondary lymphoid system and appendectomy has been associated with increased risks of hematolymphoproliferative malignancies in some studies.

MATERIALS AND METHODS

We examined the risk of lymphoid neoplasms in a large cohort of 337,437 appendectomised patients <60 years of age in Sweden 1975-2009. We estimated relative risks of non-Hodgkin lymphoma (NHL) and major subtypes, Hodgkin lymphoma (HL), chronic lymphocytic leukaemia (CLL), myeloma, and acute lymphoblastic leukaemia (ALL) versus the general population using standardised incidence ratios (SIRs) with 95% confidence intervals (CIs).

RESULTS

There was no increased risk of NHL (SIR = 0.97, 95%CI 0.88-1.06), major NHL subtypes, CLL (SIR = 0.87, 95%CI 0.70-1.06), myeloma (SIR = 1.14, 95%CI 0.96-1.33) or ALL (SIR = 1.10, 95%CI 0.80-1.47) following appendectomy. An increased risk of HL was observed among patients diagnosed with appendicitis (SIR = 1.29, 95%CI 1.07-1.54, p=0.007), especially individuals aged <20 years at surgery (SIR = 1.43, 95%CI 1.11-1.82), and for the nodular sclerosis subtype of HL (SIR = 1.55, 95%CI 1.01-2.27). A marginally increased risk of myeloma was noted among men, but the association was limited to the first few years of follow-up.

CONCLUSION

Appendectomy is not associated with any notable increase in risk of lymphoid neoplasms. A small increased risk of HL following appendicitis (rather than appendectomy per se) could reflect a true association, or shared susceptibility to infection/inflammation among individuals prone to develop HL. The association observed for myeloma may be explained by chance or surveillance bias.

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.

Appendectomy and cancer risk in Jewish BRCA1 and BRCA2 mutation carriers

Previous studies suggested that appendectomy may affect cancer risk in the general population. No data on the effect of appendectomy on cancer risk in BRCA1 and BRCA2 carriers is available. Data on appendectomy, cancer type, and age at diagnosis were collected from BRCA1 (n = 677) and BRCA2 (n = 270) female Jewish Israeli mutation carriers counseled in a single medical center. Data were also collected on 225 consecutive ovarian cancer cases treated at the same medical center. Overall, 367/947 (38.7%) of mutation carriers had breast cancer (age at diagnosis 44.1 ± 10.4 years), 142 (15.0%) ovarian cancer (53.6 ± 10.1 years), and 438 (46.25%) were asymptomatic carriers (age at counseling 41.4 ± 11.2 years). Mean age at diagnosis of consecutive ovarian cancer cases was 53.6 ± 10.1 years. Of mutation carriers, 28/367 breast cancer cases (7.6%), 15/142 ovarian cancer cases (10.6%), and 11/438 asymptomatic carriers (2.5%) underwent prior appendectomy (P = 0.001 for breast/ovarian cancer when compared with asymptomatic carriers). In all but two cases, appendectomy was performed more than 10 years before cancer diagnosis or age at counseling. Of ovarian cancer patients, 12/225 (5.3%) underwent appendectomy, and in 10 appendectomy was performed 10 years or more before ovarian cancer diagnosis (P = 0.068 when compared with inherited ovarian cancer cases). This study suggests that prior appendectomy is more frequently noted in BRCA1 and BRCA2 carriers with breast and ovarian cancer than in unaffected mutation carriers. The mechanism for this association is elusive, and future analyses of ethnically diverse mutation carriers are needed to validate these results.

[Laparoscopy for suspected appendicitis. Should an appendix that appears normal be removed?]

The question whether an appendix found to be macroscopically normal at laparoscopy for suspected appendicitis should be removed remains open to debate. Potential advantages of appendicectomy in all cases include early diagnosis of neoplastic lesions that cannot be detected macroscopically, diagnosis and cure of neurogenic appendicectomy, avoidance of diagnostic confusion in later episodes of abdominal pain, and prevention of appendicitis developing later in life. Therefore, adopting a strategy of always removing the appendix even if it is found to be uninflamed at laparoscopy seems justified as long as it does not imply an increase in postoperative morbidity. We retrospectively studied all patients undergoing laparoscopic appendicectomy in which a "normal appendix" was found and all patients undergoing diagnostic laparoscopy in our hospital during a 7-year period. Our data as well as a critical review of the literature show that removal of the appendix does not increase morbidity compared to simple diagnostic laparoscopy and should always be done when performing laparoscopy for suspected acute appendicitis.

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.

Laparoscopy in the pediatric and adolescent population

The use of laparoscopy by gynecologists in treating pediatric and adolescent patients is a relatively new phenomenon. This article discusses the specialized instrumentation necessary for operating on these patients and preoperative considerations and generalized techniques unique to this population. Although laparoscopy has a myriad of uses, the main focus is on the diagnosis and treatment of pelvic pain, adnexal masses, and pelvic inflammatory disease. Incidental appendectomy in these patients is also discussed.

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.

Incidental appendectomy--yes or no? A retrospective case study and review of the literature

OBJECTIVE

A retrospective review of appendectomies performed at the University of Kansas Medical Center between January 1, 1989, and January 1, 1994, was conducted. In addition, the literature evaluating effectiveness of incidental appendectomy in preventing future operation and morbidity from appendicitis was reviewed. The results of the two reviews were analyzed to formulate guidelines for the appropriateness of performing incidental appendectomy in association with other operative procedures.

METHOD

A retrospective review of results of appendectomies performed in 460 patients at the University of Kansas Medical Center with analysis of operative findings, pathology of the removed appendix and operative complications was performed. These results were compared with those of a systematic review of the literature utilizing a Medline search relating to the subject of incidental appendix removal.

RESULTS

Two hundred sixty-one incidental appendectomies were performed in this study of 460 patients (60%). The procedure was most commonly performed with total abdominal hysterectomy (56%), followed by oophorectomy (15%) and exploratory laparotomy (11%). Morbidity was minimal at all ages. Microscopic pathology was found in 25% of the cases.

CONCLUSION

The data from the current survey and literature review support incidental removal of the appendix in the young patient (< 35 years old). In patients 35-50 years old the literature is controversial, and the patient's clinical condition and judgment of the operating surgeon should determine whether incidental appendectomy should be performed. However, routine incidental appendectomy cannot be justified in patients greater than age 50.

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

Two hundred and seven large bowel cancer patients (93% of all cases diagnosed in a defined community between 1965 and 1976) were matched at random with non-cancer subjects of same age, sex, and place of residence. Men with cancer, aged 75 years and younger than, had a more frequent history of work in a local factory handling synthetic fiber than controls (22 versus 10; P less than 0.025). In this factory 45% of cancers occurred before age 60, while this was true in only 24% of cancer cases outside the factory (P less than 0.05). There was a greater tendency for cancers in factory workers to occur in the colon than in the rectum. Heredity was not found to be a risk factor for large bowel cancer. The rate of prior appendectomy was higher in men with colon cancer (P less than 0.05) and the rate of prior cholecystectomy was lower in females with colonic cancer (P less than 0.05). A previous hemorroidectomy was also found more often in males with colonic cancer (P less than 0.05). Long-standing severe constipation was present more often in patients with cancer (P less than 0.01). There was some evidence for a compounding influence of different risk factors, as studied by relative risk ratio. This study confirms the existence of a high risk of large bowel cancer in a group of workers in a synthetic fiber factory and suggests other factors antecedent to large bowel cancer.

Appendectomy and subsequent cancer risk

Although earlier epidemiologic studies reported a positive association between appendectomy and certain cancers, interest was limited due to lack of confidence in the study findings. However, recent morphologic studies on the immune structure of the vermiform appendix in the rabbit and man argue for a reevaluation of the appendectomy--cancer association. This paper reviews briefly the morphologic and epidemiologic literature on the subject to date. The validity of the earlier epidemiologic findings is discussed and avenues for further research assessing the relationship of appendectomy to subsequent cancer risk are proposed.

Acute appendicitis as a sign of a colorectal carcinoma

The relationship of acute appendicitis occurring previous to cancer in colon and rectum was studied in the consecutive records of 561 patients, of 40 years of age and older, operated upon with an appendectomy because of acute appendicitis. Sixteen (2.9%) of these patients were readmitted within three years because of a carcinoma in colon or rectum. The incidence of carcinoma in the colon and rectum in the population, of the same age, is only 0.1%, according to the Sweden Cancer Registry (1). This difference is statistically significant. Where acute appendicitis and colon carcinoma co-exist, the danger is that the carcinoma may be missed. Therefore, any patient over the age of 40 presenting with acute appendicitis should be carefully checked for carcinoma in the colon.

Incidental appendectomy at the time of surgery for ectopic pregnancy

Incidental appendectomy at the time of surgery for ectopic pregnancy can be performed safely in the appropriately selected patient. The added procedure does not place the patient at increased operative risk and spares her from the possible subsequent development of acute appendicitis.

Tonsillectomy and autoantibodies in patients with habitual tonsillitis

Tonsillectomy is virtually a routine operation now for ENT surgeons, but its immunological evaluation is still obscure. We have carried out an investigation in 57 patients who visited our clinic, with reference to autoantibodies by the immunofluorescence technique. We found autoantibodies at a higher frequency after tonsillectomy than before tonsillectomy in the young age group. There are studies that report close correlation of autoantibodies and malignancy. Since there are few reports that mention the relationship of the presence of autoantibodies and tonsillectomy, we have emphasized here careful follow-up of the patients from this standpoint.

Cancer and "cancer related" colorectal lesions in São Paulo, Brazil

A series of 832 necropsy specimens were studied grossly with a magnifying lens and all lesions identified were studied microscopically. The age and sex-specific prevalence of adenomatous and hyperplastic polyps is reported and results are compared with those of other populations. A correlation was made between polyps and cancer of the colon and rectum (407 cases). The data suggest that São Paulo is a community in a transitional stage between intermediate and high risk of cancer of the colon. The epidemiologic characteristics of lower rectum cancer are peculiar to some populations and appear unrelated to colon cancer. The black population of São Paulo has a higher prevalence than that reported for African negroes. The data also implicate adenomatous polyps, diverticulosis and hemorrhoids as being probably related diseases.

Rationale of incidental appendectomy

In an effort to settle the controversy regarding use of incidental appendectomy, we have reviewed the literature regarding the function of the appendix and its role in the development of cancer, incidence of acute appendicitis, pathologic findings in incidentally removed appendices, and morbidity of incidental appendectomy. Considering all parameters we conclude that incidental appendectomy is a service to the patient and should be done except where specifically contraindicated.

Appendectomy, tonsillectomy, and neoplasia

Reports in the literature that study the frequency of cancer in individual who have had their tonsils or appendix or both removed are reviewed. Some investigators found a high incidence of solid cancers - in particular, breast and colon neoplasms - in female patients who have had appendectomy, but others disagreed. The association of tonsillectomy and/or appendectomy with the later development of malignant lymphomas is not proven.