Y. H. Ho

Lymph node involvement and tumor depth in rectal cancers: An analysis of 805 patients

BACKGROUND: Superficial rectal tumors are said to involve regional lymph nodes rarely. This presumption must be proven beyond any doubt if less radical surgery is to be offered for such patients. PATIENTS AND METHODS: Eight hundred five cases (467 males; median age, 64 (range, 19–97) years) of rectal cancer were reviewed. RESULTS: Lymph node positivity, number of lymph nodes involved, lymphatic vessel, and venous and perineural invasion were significantly increased with increasing depth of invasion of tumor through the bowel wall in univariate analysis. The percentage of lymph node involvement at each tumor depth was as follows: T1, 5.7 percent; T2, 19.6 percent; T3, 65.7 percent; T4, 78.8 percent. Overall lymph node involvement was 59 percent. For patients younger than 45 years of age, the percentage of lymph node involvement was 33.3, 30, 69.3, and 83.3 percent compared with 3.1, 8.4, 64.2, and 78.8 percent for patients aged 45 years or above for T1, T2, T3, and T4, respectively. CONCLUSION: Increased depths of tumor penetration beyond T1 and age less than 45 years have an excessive incidence of lymph node positivity. The finding of lymphatic vessel invasion on biopsy is highly indicative of lymph node metastasis.

Clinical behavior of complicated right-sided and left-sided diverticulosis

PURPOSE: The aim of the study was to characterize the clinical entity of multiple right-sided (RS) diverticular disease, which is uniquely common in Asians. METHODS: Patients hospitalized with proven diverticular disease from June 1989 to January 1996 were reviewed. Data were retrieved from a prospectively collected computerized database. RESULTS: One hundred eighty consecutive patients were admitted to the Department of Colorectal Surgery, Singapore General Hospital, with multiple diverticular disease. Average age was 65.1 (standard error of the mean, 13.9) years. There were 96 men and 84 women. Women presented, on average, 8.4 years later than men (P< 0.005). Eighty-five patients (47 percent) had massive rectal bleeding, 65 (36 percent) had diverticulitis, 21 (12 percent) had obstructive symptoms, and 9 (15 percent) had enteric fistulas. The diverticula were RS in 76 patients(42 percent), left-sided (LS) in 62 patients (34 percent), and on both sides in 42 patients (24 percent). RS diverticulosis tended to present with massive rectal bleeding (42/76; 55 percent) more often than LS disease (14/62; 23 percent;P<0.005). Surgery for bleeding was also required more often for RS (17/42; 41 percent) than for LS disease (1/14; 7 percent;P<0.05); however, diverticulitis was more common on the left (RS, 25/76, 33 percent; LS, 32/62, 52 percent;P< 0.05). Seventy-eight patients (43 percent) required surgery for these complications of diverticular disease. At a mean follow-up of 15.2 (standard error of the mean, 2) months, mortality was 2 in 78 patients who underwent surgery (3 percent), and morbidity was 15 percent. CONCLUSIONS: In comparison with LS, RS diverticular disease tended to present more often with massive bleeding than with diverticulitis and fistulation. This bleeding was often more severe and required surgical intervention.

Stratifying risk factors for follow-up: a comparison of recurrent and nonrecurrent colorectal cancer.

INTRODUCTION: The selection of patients for individualized follow-up and adjuvant therapy after curative resection of colorectal carcinoma depends on finding reliable prognostic criteria for recurrence. However, such criteria are not universally accepted, and follow-up is often standardized for all patients without regard for each individuals level of risk of recurrence. Such a system of follow-up is not cost-effective. METHODS: A comparison of operative findings, pathologic features, and follow-up data of 1,731 cases of nonrecurrent colorectal cancer (821 colon, 910 rectum) with 357 cases of recurrent colorectal cancer (164 colon, 193 rectum) following potentially curative surgery was made, and results were analyzed to ascertain criteria for stratifying follow-up according to risk factors. RESULTS: Single-factor analysis showed that Dukes staging and tumor invasion were significantly associated with recurrence in both rectal and colon carcinoma. Tumor fixation and grading were additional significant factors in rectal cancer. Recurrence rates, time to recurrence, site of recurrence (locoregionalvs. distant), and pattern of metastatic spread were not significantly affected by original tumor site. Recurrence was not significantly affected by patient age and gender. Individual surgeon performance in this series had also no significant effects on tumor recurrence. With multivariate analysis only, Dukes staging and tumor invasion into adjacent tissues were found to be independent adverse prognostic factors for recurrence. CONCLUSIONS: Dukes staging and tumor penetration into adjacent tissues are the only significant adverse prognostic factors for tumor recurrence of colonic and rectal carcinoma. Tumor grade and tumor fixation are additional adverse prognostic factors in rectal cancer. Guidelines for follow-up may be based on these factors and follow-up thus stratified according to risk of developing recurrence.

Primary colorectal signet-ring cell carcinoma in Singapore

Background:   Primary colorectal signet‐ring cell carcinoma is a rare but distinctive tumour of the colon and rectum. The clinicopathological features are still controversial. The aim of this study is to review the clinicopathological features and management of this type of tumour in our hospital.

Prospective randomised trial comparing ayurvedic cutting seton and fistulotomy for low fistula-in-ano

The aim of this study was to evaluate the role of ayurvedic setons in the treatment of low fistula-in-ano. One hundred and eight patients were randomised into either conventional fistulotomy (F) or ayurvedic cutting seton insertion (C). Endpoints investigated included time to wound healing and complications of surgery. Post-operative pain scores were measured daily using a visual analog scale. Anal function was compared using a continence score. Pre- and postoperative manometry and ultrasound were also performed. After exclusions, there were 54 patients in group F and 46 in group C. There were no differences in age, sex or follow-up duration between the two groups. Healing time was similar between the groups. Group C reported more pain following operation and on the first 2–4 postoperative days, but both groups experienced the same amount of pain subsequently. In conclusion, chemical seton was more painful than conventional fistulotomy in the first few days following surgery. However, there was no difference in time to wound healing, complications or functional outcome.

Prospective, randomized trial comparing sigmoid vs. descending colonic J-pouch after total rectal excision.

AbstractPURPOSE: The aim of this study was to compare the bowel function of sigmoid vs. descending colonic J-pouches after ultralow anterior resection for rectal cancer. METHODS: A prospective, randomized trial was conducted from March 1998 to September 1999. Ninety-two consecutive patients undergoing ultralow anterior resection for cancers arising from 3 to 10 cm from the anal verge were recruited. Forty-eight patients were males; the mean ages (standard error of the mean) for patients with sigmoid and descending colon pouches, respectively, were 65.2 (3.1) years and 62.3 (3.1) years. A total of 46 patients were randomly assigned to each group. Two patients from each group were excluded; abdominoperineal resection was performed for two patients in the sigmoid pouch group and one patient in the descending pouch group. One patient in the descending pouch group had a transanal resection of a benign polyp. Dukes staging and use of postoperative chemoradiotherapy were statistically similar in both groups. All patients underwent a standardized ultralow anterior resection. A defunctioning loop ileostomy was used routinely. Anorectal physiology and bowel function questionnaires were performed at six weeks after ileostomy closure and again at 6 and 12 months after surgery. RESULTS: Median follow-up was 12 (range, 7 to 25) and 12 (range, 6 to 25) months, respectively, for sigmoid and descending pouch groups. Median tumor and anastomotic heights, time to ileostomy closure, operative time, and postoperative stay were statistically similar in both groups. There were no significant differences in stool frequency, incontinence, urgency, use of pads and antidiarrheals, sensation of incomplete evacuation, and anorectal physiology results between groups (P > 0.05). CONCLUSION: Pouches made from sigmoid or descending colon give similar bowel function after ultralow anterior resection for rectal cancers.

Clinical outcome and bowel function following total abdominal colectomy and ileorectal anastomosis in the Oriental population.

Total abdominal colectomy with ileorectal anastomosis is a commonly performed surgical procedure. The postoperative outcome of these patients, however, has not been studied in detail in the Asian population. AIM: The purpose of this study was to analyze the functional outcome of patients following total abdominal colectomy and ileorectal anastomosis. METHOD: All patients subjected to a total abdominal colectomy with ileorectal anastomosis during a six-year period from February 1989 to October 1995 were reviewed. RESULTS: Sixty-six patients (male:female, 40:26) with a mean age of 55.2 (range, 20–88) years underwent total abdominal colectomy with ileorectal anastomosis. Median follow-up after surgery was 26 (range, 4–78) months. Indications for surgery were synchronous or metachronous tumors (18), complicated pancolonic diverticular disease (15), obstructed tumors with impending perforation (13), familial adenomatous polyposis (7), slow-transit constipation (6), and others (7). Mean operative time was 137±48 minutes. Mean postoperative hospitalization was 13.3±11.9 days. Time to first bowel movement and commencement of solid diet were 4.7±1.8 and 7.2±2.4 days, respectively. Four patients had prolonged postoperative ileus. Average stool frequencies per day were 5.5 at one week, 4.3 at one month, 3.9 at six months, 3.2 at one year, and 2.9 at two years postoperatively. Thirty-three patients (50 percent) required antidiarrheal treatment for a transient period, but none required long-term therapy. Ninety-seven percent of all patients rated the functional outcome as good to excellent, and 3 percent said it was fair. There was two perioperative mortalities. Five cases required re-laparotomy, three for anastomotic complications and two for hemoperitoneum. Five patients had recurrent admissions for adhesion colic, which resolved with nonsurgical therapy. Ten patients succumbed on follow-up, six to tumor recurrence, two to unrelated cancers (stomach and bladder), and three to medical conditions. CONCLUSION: The functional outcome of ileorectal anastomosis is generally rated as good to excellent by patients. Acceptable bowel function and control is regained within six months of the operation and levels off at one year after surgery, and no patient requires long-term antidiarrheal medication.

Comparison between midline incision and limited right skin crease incision for right-sided colonic cancers

Abstract We compared the postoperative recovery parameters between patients undergoing curative surgery for right-sided colonic carcinoma using a limited skin crease incision and a traditional midline incision. A retrospective study was carried out analyzing clinical records and histopathological reports for all patients operated in one colorectal surgical unit for cancer of the right colon over a 2-year period. Palliative procedures were excluded. We analyzed demographic details, operative data (length of incision and time of operation), recovery parameters (time to parenteral analgesia, time to first oral fluid intake, time to first solid meal, time to discharge) and oncological parameters (lymph node harvest and resection margins). A total of 123 patients were analyzed, 61 with a midline incision and 62 with a skin crease incision. Demographic and tumour data (number of lymph nodes resected and resection margins) as well as postoperative complications were similar between the two groups. Wound length was significantly longer in the midline incision group (median, 20 cm vs. 10 cm; p<0.0005), as was the duration of surgery (median, 60 min vs. 45 min; p0.0005). With regard to postoperative recovery, the skin crease incision group had a significantly quicker return of bowel function (p<0.0005), shorter time to oral fluid (p<0.001) and solid food (p<0.0005) intake, and shorter hospital stay (p<0.0005) than the midline incision group. There was no statistically significant difference between the two groups concerning postoperative narcotic requirements. In conclusion, the limited skin crease approach for right colon cancer resection is technically feasible and safe. It can achieve the same standards of tumour resection and clearance as the vertical midline approach while reducing postoperative recovery.

Tumor size is irrelevant in predicting malignant potential of carcinoid tumors of the rectum

Abstract. The malignant potential and prognosis of rectal carcinoids are said to be related to tumor size. Our study assessed if size could predict the malignant potential and hence its management. All patients in the Department of Colorectal Surgery, Singapore General Hospital, who underwent surgery for rectal carcinoid tumors between February 1991 and September 2000 were analyzed. Twenty patients (11 men), median age 48 years (range, 33–77 years) were studied. Median follow-up was 40 months (range, 5–120 months). The median tumor diameter was 2.5 cm (range, 0.1–5.0 cm). Eleven patients underwent radical resection and 9 patients had local resection for a presumed benign tumor. Morbidity was 15% and postoperative death was 5%. Overall median survival was 24 months (range, 5–120 months). One patient had an anterior resection for rectal adenocarcinoma but had an incidental 0.1-cm carcinoid tumor near the resection margin which on histology was found to have carcinoid tumor metastasis to 2 out of 12 lymph nodes. In conclusion, tumor size cannot predict malignant potential as even small tumors (<1 cm) can be malignant. Accurate preoperative staging with radical surgery may be required.

The colorectal cancer recurrence support (CARES) System

Colorectal cancer has risen in incidence to become the second commonest form of cancer in Singapore. The primary treatment is surgery but up to 50% of patients still suffer from recurrence of the cancer after surgery. Early identification of recurrence will increase the effectiveness of therapy and the survival of patients. This paper describes the CARES (Cancer Recurrence Support) System, whose objective is to predict the recurrence of colorectal cancer, using Case-based Reasoning (CBR), and supported by other techniques such as data mining and natural language processing. The CARES System employs CBR to compare and contrast between the new and past colorectal cancer patient cases, and makes inferences based on those comparisons to determine the high risk patient groups. The features and functionality of the system are described.