Colon and rectal carcinoma: spatial distribution and detection

Comparison of Conventional Bipolar Electrocautery and Ultrasonic Harmonic Scalpel in Colorectal Cancer Surgeries

Background and objective

Colorectal cancer (CRC) is the third most common malignancy and the second most deadly cancer worldwide. Powered equipment has transformed modern surgery, revolutionizing the delicacy, precision, and accuracy of many surgeries. The safety and efficacy of tissue dissection and artery sealing in colorectal surgery remain highly debatable. With the increased use of minimally invasive procedures in colon and rectal surgery, energy devices for tissue dissection and vascular sealing have become widely used. In light of this, we aimed at comparing the use of bipolar electrocautery and harmonic scalpel in CRC surgeries.

Methods

Our study was a hospital-based comparative study conducted at our tertiary care hospital. Fifty patients were divided equally into two groups by block randomization, and bipolar electrocautery was used in one group, and harmonic scalpel was used in the second group during surgery. The mean operative time, blood loss, and hospital stay were calculated in both groups. The comparison between bipolar electrocautery and harmonic scalpel was evaluated using independent t-tests.

Results

The mean operative time, blood loss, and hospital stay were significantly lower in the harmonic scalpel group than in the electrocautery group. The results were statistically significant (p < 0.001).

Conclusion

Based on our findings, the harmonic scalpel is a better energy source when compared to bipolar electrocautery in CRC surgeries. 

Strategies in the management of mid and distal rectal cancer with total mesorectal excision

In the last two decades, dramatic improvement in outcome has been made in the management of rectal cancer. This has been brought about mainly by advancements in surgical technique for radical resection. With the recognition of the importance of the circumferential margin and presence of spread in the lymphovascular tissues in the mesorectum, total mesorectal excision is now commonly recognized as the optimal surgical technique for cancer of the mid and distal rectum. Not only have local control and disease-specific survival improved with the practice of total mesorectal excision, but various bodily functions have also been preserved following surgery for rectal cancer. New issues have arisen with the practice of total mesorectal excision and the strategies for management of rectal cancer require re-evaluation. In this article, the rationale and the outcomes of total mesorectal excision are reviewed. Issues such as the high anastomotic leakage rate following sphincter-preserving surgery, the poor results of abdominoperineal resection, the role of adjuvant therapy and bowel function disturbances will be addressed. Lastly, the status of the laparoscopic approach to rectal cancer with the principle of total mesorectal excision are discussed.

Diagnostic yield of barium enema examination after incomplete colonoscopy

PURPOSE

To determine the diagnostic yield of barium enema examination for neoplastic lesions larger than 1 cm in diameter in the nonvisualized portion of the colon after incomplete colonoscopy.

MATERIALS AND METHODS

A review of computerized gastroenterology and radiology databases identified 355 patients who underwent incomplete colonoscopy; 158 (44.5%) underwent subsequent barium enema examination (125 double-contrast and 33 single-contrast barium enema examinations). The radiographic reports were reviewed and compared with the endoscopic reports by one author to identify neoplastic lesions larger than 1 cm in the nonvisualized colon after incomplete colonoscopy. Six such lesions were found. In all six cases, the images from the barium enema examinations were reviewed together by two authors to determine the size, location, and morphologic features (polypoid, ulcerated, or annular) of the lesions. Medical, endoscopic, and surgical records were subsequently reviewed by one author to determine whether these represented true- or false-positive radiographic findings.

RESULTS

Barium enema examination depicted six possible lesions in the nonvisualized colon after incomplete colonoscopy; five were found to be true-positive radiographic findings, and one was found to be a false-positive finding. The five true-positive findings included two annular lesions (both adenocarcinomas) and three polypoid lesions (all tubulovillous adenomas, with high-grade dysplasia in one). Thus, neoplastic lesions larger than 1 cm were found on barium enema images in the nonvisualized colon in five (3.2%) of 158 patients after incomplete colonoscopy.

CONCLUSION

Barium enema examination had a diagnostic yield of 3.2% for neoplastic lesions larger than 1 cm in the nonvisualized colon after incomplete colonoscopy.

Incidence trends for colorectal cancer in California: implications for current screening practices

PURPOSE

The sensitivities of different screening methods for precancerous adenomas may affect the anatomical distribution of colorectal cancers. We used statewide data from California to describe time trends in the distribution of colorectal carcinoma.

SUBJECTS AND METHODS

Between 1988 and 1996, 110,378 cases of colorectal cancer were recorded in the California Cancer Registry database. Tumors proximal to, but not including, the sigmoid colon were termed "right-sided." The remaining tumors, excluding the anus, were termed "left-sided." Multivariable analyses were used to determine the effects of age, sex, and race on changes in tumor location over time.

RESULTS

During the study period, the annual incidence of colorectal cancer decreased steadily, from 200 to 162 cases per 100,000 residents. The decrease in left-sided tumors was about twice that observed on the right (-24.3% vs -11.6%). This disparity remained significant when adjusted for age, sex, and race (P = 0.0001).

CONCLUSION

The incidence of colorectal cancer in California is decreasing, particularly for left-sided (distal) tumors. Current screening recommendations, which emphasize examination of the distal colon, may need to be expanded to include the entire colon.

Proximal shift of colorectal cancer in the Australian Capital Territory over 20 years

BACKGROUND

Several studies in other countries have demonstrated a change in subsite distribution of colorectal cancer, with increasing proximal cancers. Confirmation of such a change in Australia would have implications for screening and diagnosis of colorectal cancer.

AIMS

To determine whether there has been an increase in the proportion of proximal colorectal cancers in Australia, and whether there have been changes in other clinical and pathological aspects of colorectal cancer.

METHODS

A study of the hospital files of patients with colorectal cancer diagnosed and treated at all hospitals in the Australian Capital Territory (ACT) between 1989 and 1995 was compared with data from a published study of patients diagnosed between 1969 and 1976.

RESULTS

There was a proximal shift of cancers with a significant increase in the proportion of tumours in the hepatic flexure, ascending colon and caecum, more marked for females than males. There was a corresponding reduction in distal colorectal cancers. Time from onset of symptoms to diagnosis decreased, risk factors for colorectal cancer were noted more frequently, and endoscopy replaced barium enema X-ray as the main diagnostic modality. The resectability of cancers increased, stay in hospital and 30 day mortality declined. Despite apparent earlier presentation and improved surgical resectability, the proportion of patients with localised disease (Dukes' stage A and B) had not changed significantly.

CONCLUSIONS

We have detected a number of changes in clinical and pathological aspects of colorectal cancer over a 20 year period in the ACT, including a proximal shift in the subsite distribution of colorectal cancer. These changes suggest that proximal and distal colorectal cancers may have a different aetio-pathogenesis, and have implications for the investigation of patients with suspected colorectal cancer and in screening high-risk groups.

Continued change in the distribution of colorectal carcinoma

BACKGROUND

The aim of this study was to determine whether the previously reported shift in carcinoma from the left colon to the right colon has progressed.

METHODS

The charts of 2169 patients admitted to one institution between 1979 and 1994 with a diagnosis of colorectal carcinoma were reviewed retrospectively. The study was divided into four equal intervals. The large bowel was divided into five regions: right, transverse, left, sigmoid and rectum.

RESULTS

Right-sided lesions increased from 20.6 to 29.9 per cent (P = 0.001) and rectal lesions decreased from 22.0 to 11.3 per cent (P = 0.0002) from the first to the fourth study interval. The frequency of transverse, left and sigmoid colon lesions remained relatively constant.

CONCLUSION

The continuing trend of increased incidence of right-sided lesions and decreased incidence of rectal lesions was documented. Any screening examination for carcinoma requires total examination of the colon.

The role of barium enema in detecting colorectal disease. A radiologist's perspective

The single-contrast barium enema examination remains useful for patients with acute diseases such as bowel obstruction, diverticulitis, appendicitis, and fistulas. It is also the procedure of choice for those patients who are too elderly, debilitated, or ill to cooperate with the maneuvers necessary for a double-contrast examination. The double-contrast technique is more sensitive than the single-contrast technique for detection of polyps, early inflammatory bowel disease, and lesions of the rectum. In the older population, there has been an increase in the incidence of colonic polyps and carcinomas in the right side of the colon. This emphasizes the need to examine the entire colon in these patients. The double-contrast barium enema is a safe, accurate, and cost-effective tool for accomplishing this. It is also recommended as the initial procedure in the examination of patients with positive results on fecal occult blood testing.

Case report: persistent colonic spasm concealing a carcinoma--an uncommon diagnostic pitfall of the barium enema examination

Colonic carcinomas may be missed on the barium enema examination for a variety of perceptive, technical, and interpretive reasons. We report an uncommon source of error-persistent bowel spasm resulting in concealment of an underlying carcinoma. Awareness of this association is necessary in the effort to minimize diagnostic pitfalls of the barium enema examination.

Cytochrome P450 activity and distribution in the human colon mucosa

Enzymatic activity associated with the mixed-function oxidase system was determined in microsomes prepared from the mucosal cells extracted from normal human colons. A high activity toward nitrogen oxidation reactions was observed. 1,2-Dimethylhydrazine, a colon-specific carcinogen, was metabolized at a higher rate in vitro by human colon microsomes as compared with the rat, and exhibited a km ten-fold lower, 1.03 mmol/l versus 9.68 mmol/l, respectively. This activity was inhibited by classic cytochrome P450 inhibitors; 70% inhibition was achieved using 70 mmol/l metyrapone (2-methyl-1,2-di-3-pyridyl-1-propanone), 20 mmol/l; SKF-525A (diethylaminoethyl-2,-2-diphenylvalerate HCl), or 350 mumol/l n-octylamine. These data suggest the presence of a stable, active mixed-function oxidase system in the human colon mucosa which has a preferential activity toward nitrogenous compounds and provides a mechanism for the activation of carcinogens. Its distribution in the colon appears to parallel the reported incidence of human colonic carcinomas.

Spatial clustering of multiple hyperplastic, adenomatous, and malignant colonic polyps in individual patients

Analysis of relative polyp locations in 426 consecutive patients with multiple colonic polyps found on colonoscopy showed novel findings. First, synchronous and metachronous neoplastic polyps showed spatial clustering in individual patients. For example, patients with their largest neoplasm in the cecum or proximal ascending colon, had 34.3 percent +/- 4.6 percent (standard error) of their other colonic neoplasms in the same location. Second, hyperplastic polyps showed spatial clustering in individuals that was statistically significantly greater than expected from the increased hyperplastic polyp concentration in the rectum and sigmoid. Third, hyperplastic polyps showed spatial clustering with neoplastic polyps; this clustering was similar in magnitude to clustering for exclusively hyperplastic or neoplastic polyps. In contrast, lipomas were not spatially clustered with hyperplastic and neoplastic polyps. The magnitude of clustering between hyperplasia and neoplasia showed a closer association between these histologic types than previously appreciated. Because of clustering, regions with prior polyps appear to merit closer surveillance. These findings suggest clinical study, using a randomized controlled clinical trial, of whether a patient who had only rectal and sigmoid adenomas on initial and follow-up colonoscopy should have surveillance with flexible sigmoidoscopy alternating annually with colonoscopy. A patient with a prior cecal adenoma should have surveillance only with a complete colonoscopy or adequate cecal views on barium enema.

Colorectal carcinomas: diagnostic implications of their changing frequency and anatomic distribution

This retrospective review included 1,694 consecutive cases of colorectal carcinoma diagnosed at the University of Chicago Medical Center during a 25-year period (1960 through 1984). The number and percentage of tumors occurring within 7 anatomic segments of the large bowel were determined. The statistical data for a recent 5-year interval were then compared with those of the 2 preceding decades. There was a 10.2% increase in the frequency of cancers originating in the cecum or ascending colon, while rectal and rectosigmoid carcinomas declined by 15.8% during the same study period. These data provide further evidence for a progressive left-to-right shift in cancer distribution within the colon during the past quarter century. Currently, the most proximal and distal 20-25 cm segments of the large bowel (cecum or ascending colon versus rectum and rectosigmoid) each harbor approximately 25% of the tumors. Therefore, the classic medical teaching that over 50% of colorectal cancers would be detectable by digital examination and/or proctosigmoidoscopy is no longer accurate. This documented increase in proximal colon cancers and redistribution of lesions within various large bowel segments indicate the growing importance of barium enema and colonoscopy as the optimal techniques for detection of colorectal neoplasms.

Colorectal cancer detection with the 60 cm flexible sigmoidoscope in a solo general internist's office

Emphasis is placed on the importance of early detection of colorectal cancer by the primary care physician using the 60 cm flexible sigmoidoscope. A training format for this procedure is proposed. The author, trained according to this format, found 49 polyps and three carcinomas among his first 365 randomly chosen patients. Of these 317 (87%) were asymptomatic, having no risk factors. The average distance of insertion was 53 cm and the average examination time was 20 minutes. The calculated cost for these 365 patients was approximately +60,000, and the estimated average cost for a potentially curable colorectal cancer detection was approximately +20,000. Although a relatively long examination time may be necessary for the beginner, the author concludes that the primary care physician can be readily trained to handle the 60 cm flexible sigmoidoscope safely and cost effectively.

The value of a barium enema in the investigation of patients with rectal carcinoma

A review of 545 patients with clinically diagnosed rectal carcinoma was conducted to determine the diagnostic usefulness of pre-operative barium enema and the frequency with which it was employed. Only 118 patients underwent pre-operative barium enema (21.7%). This successfully outlined the whole colon in 107 (90%). Synchronous carcinomas were detected in 9.3% of patients who underwent complete barium enema, compared to 4.3% of those who underwent laparotomy alone (P less than 0.05). Polyps were found in 23.4% of patients who had a barium enema but in only 14.7% of those who did not (P less than 0.05). Twenty-nine per cent of synchronous carcinomas and 11% of polyps were proximal to the descending colon and would have been beyond the reach of a flexible sigmoidoscope. Barium enema remains a useful investigation in patients with rectal carcinoma. It will outline the whole colon in most cases and will result in the detection of more synchronous carcinomas and polyps than if the surgeon relies on operative palpation alone.

Carcinoma of the colon and rectum. Tumors missed by radiologic examination in 61 patients

Radiologic examinations preceding the diagnosis of colorectal carcinomas were retrospectively scrutinized in 708 patients with 731 carcinomas that were radiographically investigated 741 times. Sixty-four lesions were missed 74 times, giving a 90% sensitivity of the radiographic methods used. Of the errors, 82% were perceptive, and 3% were interpretative. Eleven examinations in nine patients revealed no lesions, although the examinations were done within 2 years of the diagnosis of a carcinoma. Missed lesions were more common than expected in the cecum and the ascending colon (P less than 0.001), and 18% of the patients had multiple tumors (expected incidence 3.6%, P less than 0.001). The median delay in diagnosis was 20 months, and patients whose diagnosis was delayed for a long time tended to have more advanced carcinomas at diagnosis. As a lesion was identified either at the initial examination or retrospectively 730 of 741 times, the potential sensitivity of the radiographic methods used was 99%. It is concluded that barium enema is still an excellent method for the detection of colorectal carcinoma provided that perceptive errors can be minimized.

Screening of colorectal cancer

Colorectal cancer (CRC) remains a cancer in a disappointing location. However, its location clearly has an advantage that could theoretically permit efficient secondary prevention: the preceding of the cancer by a benign lesion, ie, the adenoma. Complete colonoscopy and its substitute, the double-contrast barium enema, and their specific limitations, must be reserved for high-risk patients: hereditary cancers and ulcerative colitis. For all the others, ie, adults of 45 years of age and with standard risks, the proposal is either to select the patients to be colonoscoped through occult blood testing of the stools or to perform a fiber sigmoidoscopy or a combination of both. Although imperfect, both methods allow the detection of polyps and cancers at a presymptomatic stage, when they are either benign or malignant, but localized and with a better prognosis. However, the absolute proof of the benefits of this strategy of screening would be the demonstration by controlled studies of a prolonged survival rate or a decrease in morbidity. Until now, this proof is not fully available.