ABC of colorectal diseases. Anatomy and physiology of the colon, rectum, and anus

Frailty and Colorectal Surgery: Review and Concept of Cancer Frailty

Frailty is characterized by reduced physiological reserves across multiple systems. In patients with frailty, oncological surgery has been associated with a high rate of postoperative complications and worse overall survival. Further, given that cancer and frailty can co-exist in the same patient, cancer and cancer-related symptoms can rapidly accelerate the progression of baseline frailty, which we have termed "cancer frailty". This distinction is clinically meaningful because the prioritization of interventions and the treatment outcomes may differ based on health conditions. Specifically, in patients with cancer frailty, improvements in frailty may be achieved via surgical removal of tumors, while prehabilitation may be less effective, which may in turn result in delayed treatment and cancer progression. In this review, we focused on challenges in the surgical treatment of non-metastatic colorectal cancers in patients with frailty, including those related to decision making, prehabilitation, and surgery. Potential recommendations for treating patients with cancer frailty are also discussed.

Tissue Engineering for Gastrointestinal and Genitourinary Tracts

The gastrointestinal and genitourinary tracts share several similarities. Primarily, these tissues are composed of hollow structures lined by an epithelium through which materials need to flow with the help of peristalsis brought by muscle contraction. In the case of the gastrointestinal tract, solid or liquid food must circulate to be digested and absorbed and the waste products eliminated. In the case of the urinary tract, the urine produced by the kidneys must flow to the bladder, where it is stored until its elimination from the body. Finally, in the case of the vagina, it must allow the evacuation of blood during menstruation, accommodate the male sexual organ during coitus, and is the natural way to birth a child. The present review describes the anatomy, pathologies, and treatments of such organs, emphasizing tissue engineering strategies.

MutL homolog 1 methylation and microsatellite instability in sporadic colorectal tumors among Filipinos

BACKGROUND

Colorectal cancer (CRC) ranks third in terms of incidence and second in mortality worldwide. In CRC, the silencing of mismatch repair genes, including the mutL homolog 1 (hMLH1) has been linked to microsatellite instability (MSI), the lengthening or shortening of microsatellite repeats. Very limited data have been presented so far on the link of hMLH1 methylation and MSI in Southeast Asia populations with sporadic CRC, and on its clinical significance.

AIM

To investigate the significance of the MSI status and hMLH1 methylation in CRC Filipino patients.

METHODS

Fifty-four sporadic CRC patients with complete clinical data were included in this study. Genomic DNA from CRC tumor biopsies and their normal tissue counterparts were profiled for MSI by high resolution melting (HRM) analysis using the Bethesda Panel of Markers (BAT25, BAT26, D2S123, D5S346, and D17S250). hMLH1 methylation screening was performed using bisulfite conversion and methylation specific polymerase chain reaction. Statistical analysis was conducted to calculate their associations to clinicopathological characteristics and survival relevance (Kaplan-Meier curves and the log-rank test).

RESULTS

hMLH1 methylation was observed in 9% and 35% of CRC and normal samples, respectively. Higher incidence of consistently methylated hMLH1 found in both normal and CRC was noticed for relation to location of tumor (P < 0.05). As for MSI status, D2S123 the most common unstable microsatellite and MSI-high (MSI-H) was the most common MSI profile, counted for 46% and 50% of normal and CRC tissues, respectively. The presence of MSI-low (MSI-L) and microsatellite stable (MSS) was 43% and 11% for normal, and 31% and 19% for CRC samples. The mean month of patients’ survival was shorter in patients whose normal and tumor tissues had methylated compared to those with unmethylated hMLH1 and with MSI-H compared to those with MSI-L/MSS (P < 0.05). This was supported by significant difference in Kaplan-Meier with log-rank analysis. This data indicated that hMLH1 methylation and high MSI status have prognostic value.

CONCLUSION

This study showed the clinical significance of hMLH1 methylation and MSI status in sporadic CRC Filipino patients, especially in the normal part of the tumor.

The Sphincter of O'Beirne - Part 1: Study of 18 Normal Subjects

BACKGROUND

Gastroenterologists have ignored or emphasized the importance of the rectosigmoid junction in continence or constipation on and off for 200 years. Here, we revisit its significance using high-resolution colonic manometry.

METHODS

Manometry, using an 84-channel water-perfused catheter, was performed in 18 healthy volunteers.

RESULTS

The rectosigmoid junction registers as an intermittent pressure band of 26.2 ± 7.2 mmHg, or intermittent phasic transient pressure increases at a dominant frequency of 3 cpm and an amplitude of 28.6 ± 8.6 mmHg; or a combination of tone and transient pressures, at a single sensor, 10-17 cm above the anal verge. Features are its relaxation or contraction in concert with relaxation or contraction of the anal sphincters when a motor pattern such as a high-amplitude propagating pressure wave or a simultaneous pressure wave comes down, indicating that such pressure increases or decreases at the rectosigmoid junction are part of neurally driven programs. We show that the junction is a site where motor patterns end, or where they start; e.g. retrogradely propagating cyclic motor patterns emerge from the junction.

CONCLUSIONS

The rectosigmoid junction is a functional sphincter that should be referred to as the sphincter of O'Beirne; it is part of the "braking mechanism," contributing to continence by keeping content away from the rectum. In an accompanying case report, we show that its excessive presence in a patient with severe constipation can be a primary pathophysiology.

Basics to advances in nanotherapy of colorectal cancer

Colorectal cancer (CRC) is the third most common cancer existing across the globe. It begins with the formation of polyps leading to the development of metastasis, especially in advanced stage patients, who necessitate intensive chemotherapy that usually results in a poor response and high morbidity owing to multidrug resistance and severe untoward effects to the non-cancerous cells. Advancements in the targeted drug delivery permit the targeting of tumor cells without affecting the non-tumor cells. Various nanocarriers such as liposomes, polymeric nanoparticles, carbon nanotubes, micelles, and nanogels, etc. are being developed and explored for effective delivery of cytotoxic drugs to the target site thereby enhancing the drug distribution and bioavailability, simultaneously subduing the side effects. Moreover, immunotherapy for CRC is being explored for last few decades. Few clinical trials have even potentially benefited patients suffering from CRC, still immunotherapy persists merely an experimental alternative. Assessment of the ongoing and completed trials is to be warranted for effective treatment of CRC. Scientists are paying efforts to develop novel carrier systems that may enhance the targeting potential of low therapeutic index chemo- and immune-therapeutics. Several preclinical studies have revealed the superior efficacy of nanotherapy in CRC as compared to conventional approaches. Clinical trials are being recruited to ascertain the safety and efficacy of CRC therapies. The present review discourses in a nutshell the molecular interventions including the genetics, signaling pathways involved in CRC, and advances in various strategies explored for the treatment of CRC with a special emphasis on nanocarriers based drug targeting.

A novel retrieval technique for large colorectal tumors resected by endoscopic submucosal dissection: tumor extraction by defecation

BACKGROUND AND STUDY AIMS

Endoscopic submucosal dissection (ESD) has been developed to facilitate en bloc resection of large lesions. However, it is laborious to retrieve the large colorectal specimens. We propose a novel retrieval technique using a Valsalva maneuver, known as Tumor Extraction by Defecation (TED).

CASE SERIES

A total of nine lesions (median size 88 mm, maximum 225 mm; proximal colon three, rectum six) that could not be easily retrieved using net forceps were subsequently removed by TED. The rectum was filled with water through the colonoscope. The patient then strained to evacuate the specimen, facilitated by an almost straight anorectal angle. All specimens were retrieved without fragmentation, within minutes. Histology was assessed appropriately, including an adenoma in two and mucosal cancer in seven. All cut margins were verified to be negative. No adverse events occurred.

CONCLUSIONS

TED is a promising technique for retrieving large colorectal specimens after ESD.

Chronic methadone use, poor bowel visualization and failed colonoscopy: A preliminary study

AIM: To examine effects of chronic methadone usage on bowel visualization, preparation, and repeat colonoscopy.

METHODS: In-patient colonoscopy reports from October, 2004 to May, 2009 for methadone dependent (MD) patients were retrospectively evaluated and compared to matched opioid naive controls (C). Strict criteria were applied to exclude patients with risk factors known to cause constipation or gastric dysmotility. Colonoscopy reports of all eligible patients were analyzed for degree of bowel visualization, assessment of bowel preparation (good, fair, or poor), and whether a repeat colonoscopy was required. Bowel visualization was scored on a 4 point scale based on multiple prior studies: excellent = 1, good = 2, fair = 3, or poor = 4. Analysis of variance (ANOVA) and Pearson χ² test were used for data analyses. Subgroup analysis included correlation between methadone dose and colonoscopy outcomes. All variables significantly differing between MD and C groups were included in both univariate and multivariate logistic regression analyses. P values were two sided, and < 0.05 were considered statistically significant.

RESULTS: After applying exclusionary criteria, a total of 178 MD patients and 115 C patients underwent a colonoscopy during the designated study period. A total of 67 colonoscopy reports for MD patients and 72 for C were included for data analysis. Age and gender matched controls were randomly selected from this population to serve as controls in a numerically comparable group. The average age for MD patients was 52.2 ± 9.2 years (range: 32-72 years) years compared to 54.6 ± 15.5 years (range: 20-81 years) for C (P = 0.27). Sixty nine percent of patients in MD and 65% in C group were males (P = 0.67). When evaluating colonoscopy reports for bowel visualization, MD patients had significantly greater percentage of solid stool (i.e., poor visualization) compared to C (40.3% vs 6.9%, P < 0.001). Poor bowel preparation (35.8% vs 9.7%, P < 0.001) and need for repeat colonoscopy (32.8% vs 12.5%, P = 0.004) were significantly higher in MD group compared to C, respectively. Under univariate analysis, factors significantly associated with MD group were presence of fecal particulate [odds ratio (OR), 3.89, 95% CI: 1.33-11.36, P = 0.01] and solid stool (OR, 13.5, 95% CI: 4.21-43.31, P < 0.001). Fair (OR, 3.82, 95% CI: 1.63-8.96, P = 0.002) and poor (OR, 8.10, 95% CI: 3.05-21.56, P < 0.001) assessment of bowel preparation were more likely to be associated with MD patients. Requirement for repeat colonoscopy was also significant higher in MD group (OR, 3.42, 95% CI: 1.44-8.13, P = 0.01). In the multivariate analyses, the only variable independently associated with MD group was presence of solid stool (OR, 7.77, 95% CI: 1.66-36.47, P = 0.01). Subgroup analysis demonstrated a general trend towards poorer bowel visualization with higher methadone dosage. ANOVA analysis demonstrated that mean methadone dose associated with presence of solid stool (poor visualization) was significantly higher compared to mean dosage for clean colon (excellent visualization, P = 0.02) or for those with liquid stool only (good visualization, P = 0.01).

CONCLUSION: Methadone dependence is a risk factor for poor bowel visualization and leads to more repeat colonoscopies. More aggressive bowel preparation may be needed in MD patients.

[Right colon diverticulitis]

Diverticulitis involving the right colon is uncommon in the Occident; only one case for every 300 cases of appendicitis occurs in Western countries compared to a ratio of 1/40-1/180 in Asia. The preferential localization of diverticula in the right colon among Asiatics is probably due to genetic factors. In Asia as in the West, a right colon diverticulum is more likely to cause hemorrhage than diverticulitis. The peak age of symptoms is 40-45 years and the sex ratio is 1:1. The patient most commonly presents with symptoms suggestive of acute appendicitis, acute localized peritonitis, or, more rarely, a psoas abscess. Clinical exam reveals an inflammatory mass in the right lower quadrant in 30% of cases; diffuse peritonitis, large abscesses, and fistulae are rare. Helical CT scan is the best tool for establishing the diagnosis and also helps to rule out other possible etiologies in the differential diagnosis-particularly a perforated right colon cancer. In noncomplicated cases with convincing evidence for the diagnosis by CT scan, a conservative (non-surgical) treatment with antibiotics is possible; a later stage colonoscopy will rule out other colonic lesions. More commonly, the correct diagnosis is only made after embarking on an appendectomy via a McBurney incision; the surgical strategy thereafter depends on the level of suspicion regarding the diagnosis and the extent and complexity of the diverticulitis. Therapeutic options may be conservative (appendectomy), limited (diverticulectomy, or extensive (ileocecal resection or right hemicolectomy). For complicated disease (abscess, localized perforation), an aggressive surgical approach is warranted. Surgical strategies need to be validated, particularly in the light of the increasing use of the laparoscopic approach for suspected appendicitis.

Free transverse colon transplantation for functional reconstruction of intra-oral lining: a clinical and histologic study

A variety of free-tissue transplantations are available for oropharyngeal (lining) reconstruction. The most commonly used flap, the radial forearm flap, is relatively thin, adaptable, and reliable but does not provide lubrication. In this study, the potential of the transverse colon to provide a lubricating tissue for replacement of oral lining was investigated. Eleven patients requiring replacement of oral lining received transverse colon flap transplantation between November of 1993 and December of 1995. There was one complete flap loss and one partial loss. Flap size used for reconstruction averaged 40.4 cm2, and average vessel length and diameter were 7 cm and 2.0 mm, respectively. In a follow-up period from 15 to 48 months, all colon flaps proved to be durable with continuous lubrication function. Histologic assessment of the transplanted colon flaps at various postoperative times showed an adequate amount of mucus-secreting goblet cells even after irradiation. There was no donor-site morbidity. The main disadvantage seemed a tendency to transplant too much tissue, which resulted in formation of redundant pockets affecting food handling. Thus, 8 out of 10 patients with flap survival required one to three debulking procedures. Given an accurate estimation of the area of mucosa defect and adequate trimming of the colon flaps, the transverse colon flap offers a good alternative for reconstruction of the oral lining, especially when lubrication is desirable in cases with large defects and preoperative or postoperative irradiation, or in case a radial forearm flap is not available.

Straining at stool and laxative taking in an English population

A population-based sample of 834 men (ages 40-69 years) and 1058 women (25-29 years) was investigated with respect to straining to defecate, stool form, bowel habit, and use of laxatives, by means of a questionnaire and a three-stool record form. Straining was common but, contrary to standard teaching, far from universal. It was unrelated to age but was commoner in women than men. Many people underestimated how often they strained. Overall, 32% of defecations in women and 22% of defecations in men were associated with straining to start and 15% and 9%, respectively, with straining to finish. Straining was to some extent related to stool type: the lumpier a stool, the more often it elicited straining. However, it seems likely that straining in some people is just a habit. Use of laxatives was found to be less prevalent than in the past, and most people with evidence of constipation did not use them. Use of laxatives increased with age, and some older people used them inappropriately. The most popular laxatives were based on phenolphthalein, senna, or magnesium.