Mucinous adenocarcinoma showing different clinicopathological and molecular characteristics in relation to different colorectal cancer subgroups.

BACKGROUND: Mucinous adenocarcinoma (MAC) is frequently reported to be associated with patients of young-age sporadic colorectal cancer (YSCC) and hereditary nonpolyposis colorectal cancer (HNPCC). This study is aimed to investigate whether the clinicopathological characteristics of MAC of HNPCC patients are distinct from those of YSCC patients. PATIENTS AND METHODS: Eighty-two HNPCC and 68 YSCC patients recorded in the colorectal cancer registry of Chang Gung Memorial Hospital at Linkou, Taiwan, between January 1, 1995 and December 31, 2001 were included in this study. Clinicopathological and molecular variables of MAC and non-MAC of HNPCC and YSCC patients were compared accordingly. RESULTS: Compared to non-MAC, MAC significantly showed higher frequencies of poor differentiation (32% vs. 8.2%, p = 0.001), advanced tumor stage (76% vs. 47%, p = 0.002), loss of mismatch repair protein (MMR) expression (74% vs. 44%, p = 0.023), and increased MUC2 expression (98% vs. 61%, p < 0.001). MAC of HNPCC patients showed predominant right-sided colon involvement, whereas MAC of YSCC patients displayed predominance in the left colon (79% vs. 22%, p = 0.001). Among the non-MAC counterparts, more differences were detectable including tumor stage, loss of MMR expression, and increased MUC1 expression. Furthermore, both MAC and non-MAC of YSCC patients showed higher frequencies of advanced tumor stage (81% vs. 62%, p = 0.072). In contrast, the incidence of loss of MMR expression in MAC and non-MAC of HNPCC patients is not significantly different (86% vs. 70%, p = 0.323). CONCLUSIONS: Significantly different tumor localization was observed between mucinous YSCC (left colon predominance) and mucinous HNPCC (right colon predominance).

Mutation analysis of the APC gene in Taiwanese FAP families: low incidence of APC germline mutation in a distinct subgroup of FAP families.

Familial adenomatous polyposis (FAP) is an autosomal-dominant disease caused by germline mutations in the adenomatous polyposis coli (APC) gene. The affected individuals develop colorectal polyposis and show various extra-colonic manifestations. In this study, we aimed to investigate the genetic and clinical characteristics of FAP in Taiwanese families and analyze the genotype-phenotype correlations. Blood samples were obtained from 66 FAP patients registered in the hereditary colorectal cancer database. Then, germline mutations in the APC genes of these 66 polyposis patients from 47 unrelated FAP families were analyzed. The germline-mutation-negative cases were analyzed by performing multiplex ligation-dependent probe amplification (MLPA) and single-strand conformation polymorphism (SSCP) analysis of the MUTYH gene. Among the analyzed families, 79% (37/47) of the families showed 28 APC mutations, including 19 frameshift mutations, 4 nonsense mutations, 3 genomic deletion mutations, 1 missense mutation, and 1 splice-site mutation. In addition, we identified 15 novel mutations in 32% (15/47) of the families. The cases in which APC mutations were not identified showed significantly lower incidence of profuse polyposis (P = 0.034) and gastroduodenal polyps (P = 0.027). Furthermore, FAP families in which some affected individuals had less than 100 polyps showed significant association with low incidence of APC germline mutations (P = 0.002). We have added the APC germline-mutation data for Taiwanese FAP patients and indicated the presence of an FAP subgroup comprising affected individuals with nonadenomatous polyps or less than 100 adenomatous polyps; this form of FAP is less frequently caused by germline mutations of the APC gene.

Mismatch repair protein expression in Amsterdam II criteria-positive patients in Taiwan.

BACKGROUND: Hereditary non-polyposis colorectal cancer (HNPCC) is characterized genetically by germline mutations in DNA mismatch repair (MMR) genes. Immunohistochemistry (IHC) has high sensitivity and specificity for identifying MMR-deficient tumours. This study investigated the clinical presentations and frequency of HNPCC in Taiwan by combined Amsterdam II criteria (AC-II) and IHC. METHODS: In 1995-2003, 7108 patients with primary colorectal cancer registered in Chang Gung Memorial Hospital's Colorectal Cancer Registry were screened using AC-II. Tumour specimens were analysed for MMR protein expression by IHC, and relevant clinicopathological details were documented. RESULTS: Some 83 patients fulfilled the AC-II. Clinicopathologically, 43 patients (52 per cent) had proximal tumours, ten (12 per cent) had poorly differentiated cancers, 17 (20 per cent) had mucinous adenocarcinoma and 51 (61 per cent) had stage I-II tumours. Seventeen patients developed second primary colonic and extracolonic cancers over a mean 7.2-year follow-up. Immunohistochemically, 58 patients were MMR protein deficient. They had a significantly earlier age of onset (P < 0.001), more proximal tumour location (P = 0.002), less advanced tumour stage (P = 0.008) and more second primary cancers (P = 0.017) compared with MMR-competent patients. CONCLUSION: These data show significant differences in clinical features between MMR protein-deficient and MMR competent subgroups.

Humoral response to p53 in human colorectal tumors: a prospective study of 1,209 patients.

p53 Antibodies (p53-Abs) have been detected in the serum of a proportion of colorectal cancer (CRC) patients. It is not yet known at which stage during colorectal tumor progression p53-Abs appear in the serum. The utility of these antibodies as markers for CRC prognosis remains to be clarified. Using a quantitative enzyme-linked immunosorbent assay, we analyzed serum samples from 998 CRC patients and from 211 patients with polyp. Levels of p53-Abs were defined as negative (<10 U/microL), low (10-76 U/microL) and high (>76 U/microL). Overall, 13.0% of CRC patients and less than 1% of polyp patients had increased serum p53-Ab levels. High p53-Ab levels were only seen in patients with invasive carcinomas. The parameters that were significantly and independently associated with a greater frequency of high p53-Ab levels were the left colon (odds ratio [OR] = 3.4; 95% CI = 1.1-10.5), the rectum (OR = 2.9; 95% CI, 1.0-8.8) and advanced lymph node metastasis (OR = 4.6; 95% CI, 2.2-9.6). In univariate analysis, patients with high p53-Ab levels had a shorter survival times than did those without (p = 0.007). However, the significant effect disappeared in a Cox regression model adjusting for sex, age, tumor location, carcinoembryonic antigen levels, gross findings, histologic grade, mucin production and TNM stage. Thus, autoantibodies against p53 occur with tumor progression in multistep colorectal carcinogenesis and increase with advanced node metastasis. Furthermore, the seemingly adverse effect of high p53-Ab levels on the survival of CRC patients may be explained by other prognostic factors.

Risk factors for surgical site infection after elective resection of the colon and rectum: a single-center prospective study of 2,809 consecutive patients.

OBJECTIVE: To identify the risk factors for surgical site infection (SSI) in patients undergoing elective resection of the colon and rectum. SUMMARY BACKGROUND DATA: SSI causes a substantial number of deaths and complications. Determining risk factors for SSI may provide information on reducing complications and improving outcome. METHODS: The authors performed a prospective study of 2,809 consecutive patients undergoing elective colorectal resection via laparotomy between February 1995 and December 1998 at a single institution. The outcome of interest was SSI, which was classified as being incisional or organ/space with or without clinical leakage. A likelihood ratio forward regression model was used to assess the independent association of variables with SSIs. RESULTS: The overall SSI, incisional SSI, and organ/space SSI with and without clinical anastomotic leakage rates were 4.7%, 3%, 2%, and 0.8%, respectively. Risk factors for overall SSI were American Society of Anesthesiology (ASA) score 2 or 3 (odd ratio [OR] = 1.7), male gender (OR = 1.5), surgeons (OR = 1.3-3.3), types of operation (OR = 0.3-2.1), creation of ostomy (OR = 2.1), contaminated wound (OR = 2.9), use of drainage (OR = 1.6), and intra- or postoperative blood transfusion (1-3 units, OR = 5.3; >/=4 units, OR = 6.2). However, SSIs at specific sites differed from each other with respect to the risk factors. Among a variety of risk factors, only blood transfusion was consistently associated with a risk of SSI at any specific site. CONCLUSIONS: In addition to ASA score and surgical wound class, blood transfusion, creation of ostomy, types of operation, use of drainage, sex, and surgeons were important in predicting SSIs after elective colorectal resection.

Primary colorectal lymphoma.

PURPOSE: The purpose of this study was to review the clinical presentation and characteristics of primary colorectal lymphoma, analyze the prognostic factors, and assess the results of treatment with adjuvant chemotherapy. METHODS: We identified 37 cases at our institution between 1980 and 1996. They comprised 0.48 percent of all cases of colon malignancies (37/7,658) during this period. The following clinical information was obtained: age, gender, signs and symptoms, tumor site, tumor size, histology grade, pathology, and adjuvant chemotherapy. RESULTS: The most common presenting signs and symptoms were abdominal pain (62 percent), abdominal mass (54 percent), and weight loss (43 percent). The most frequent site of involvement was the cecum (45 percent). Histologically, 29 (78 percent) were classified as high-grade, and 8 (22 percent) as intermediate-grade-to-low-grade lymphoma. Nine (24.3 percent) of the cases were Stage EI, 23 (62.2 percent) were Stage EII, and 5 (13.5 percent) were Stage EIV. Twenty-one (57 percent) cases received adjuvant chemotherapy. The five-year survival rate was 33 percent for all patients and 39 percent for patients treated with combination chemotherapy. Overall median survival time was 24 months and 36 months for those with adjuvant chemotherapy. Only histology grade, among the factors examined, was a significant prognostic factor for survival. The mean survival time of the patients with Stage II disease who received chemotherapy was 117.4 months, and it was 47.9 months for the patients with Stage II disease who did not received chemotherapy. CONCLUSIONS: In our retrospective study high-grade lymphoma was the only significant adverse prognostic factor for survival. Receiving adjuvant chemotherapy significantly improved survival in patients with Stage II disease. Patients with diffuse large-cell type had better survival than patients with small noncleaved-cell type in Stage II high-grade lymphoma.

A simplified regimen of weekly high dose 5-fluorouracil and leucovorin as a 24-hour infusion in patients with advanced colorectal carcinoma.

BACKGROUND: Reports of in vitro experiments in colorectal carcinoma cells suggest that prolonged cellular exposure to 5-fluorouracil (5-FU) combined with relatively low concentrations of leucovorin (LV) provides optimal enhancement of 5-FU efficacy. In this study, a simplified regimen of weekly 24-hour infusion of high dose 5-FU combined with a relatively low dose of LV was used to treat patients with advanced colorectal carcinoma. METHODS: Thirty-six patients with advanced colorectal carcinoma received 5-FU, 2600 mg/m2, admixed with LV, 100 mg/m2, in a portable infusion pump administered intravenously over a 24-hour period. High dose 5-FU/LV was delivered once a week for 5 consecutive weeks followed by a 1-week recovery period. All patients were assessable for toxicity and response. RESULTS: Two complete responses and 15 partial responses were observed (response rate of 47.2%; 95% confidence interval, 30.1-64.4%). The median response duration was 9.6 months. The median survival and time to progression were 11.9 months and 7.1 months, respectively. The toxicity was mild and acceptable. The major dose-limiting factors were hand-foot syndrome and fatigue. CONCLUSIONS: This simplified regimen of weekly 24-hour continuous infusion of high dose 5-FU/LV is an effective regimen in the treatment of patients with advanced colorectal carcinoma. Further study of the pharmacokinetics of combination therapy with 5-FU and LV as used in this regimen and its correlation with response and toxicity is warranted.

Segmental colectomy in the management of colonic inertia.

Subtotal colectomy with ileorectostomy has been proposed for the management of colon inertia-type constipation. However, many patients experience frequent bowel movements, watery diarrhea, or both after such a treatment. The purpose of this study is to determine the proper colectomy with which to treat colon dysmotility constipation without the negative side effects of frequent bowel movements, watery diarrhea, or both. Forty idiopathic constipation patients were studied. All of the patients showed a prolonged right or left colon transit time and normal transit time of the sigmoid and rectum. They received different types of colectomies (left, right, and subtotal) according to the distribution or accumulation of markers in the colon. Within 3 months of surgery, all of the patients experienced a dramatic improvement of their symptoms without frequent bowel movements or watery diarrhea. No significant complications developed after surgery. All the patients were followed up for at least 2 years. Most of them (37 cases) still had satisfactory bowel movements and no other constipation symptoms. However, 3 of the 40 cases developed symptoms of constipation 1 1/2 to 2 years after surgery. They all received subtotal colectomy with ileorectal anastomosis subsequently. They reobtained satisfactory bowel movements and experienced a subsidence of other constipation symptoms 3 months later. These results suggest that directed segmental colectomy can improve colonic inertia constipation without the consequence of frequent bowel movements and diarrhea.

Foley catheter-assisted endoscopic treatment of severe anastomotic stenosis following anterior resection of the rectum.

Rectal stenosis following low anterior resection is common. Several methods of treatment have been described. We introduce a simple method for the treatment of anastomotic stenosis using a conventional proctoscope and an electric knife with a Foley catheter as an anvil. Under direct vision, this technique can afford accurate and safe incision of stenosis.

Internal iliac artery aneurysmo-rectal fistula associated with multiple aortoiliac aneurysms.

Fistular communication between an internal iliac artery aneurysm and rectum presenting as massive lower gastrointestinal tract bleeding is a rare entity in clinical practice. Prompt diagnosis and experienced therapeutic application determine the outcome. Herein we report the successful management of such a complication. A 68-year-old male had multiple aneurysms over the abdominal aorta and bilateral iliac arteries. It was the largest aneurysm arising from the right internal iliac artery which ruptured into the rectum and resulted in massive hematochezia. After extraanatomical bypass with right axillo-femoral and femoro-femoral crossover grafts to restore the circulation to the bilateral lower limbs, the infrarenal abdominal aorta just immediately above the proximal aneurysm was transected and closed as a blind stump. All the aneurysms were included in this resection and as much of the infected aneurysm tissue was debrided as possible. The rectum was exteriorized using Hartmann's procedure. The patient survived the operation and was discharged in good condition.

Pathogenetic implications of DNA nondiploidy in colorectal cancers.

PURPOSE: Several studies propose that proximal and distal colorectal cancers have a different pathogenesis. We tested the hypothesis using flow cytometric DNA analysis. METHODS: DNA analysis was performed in 719 patients with colorectal cancer. In addition, histopathologic data were re-evaluated in a blinded fashion by a single pathologist. RESULTS: Distal tumors were more often nondiploid than were proximal tumors (61 vs. 49 percent; P = 0.015). Compared with the proximal tumor, distal tumors were smaller (P = 0.0001) and had less desmoplastic reaction (39 vs. 53 percent; P = 0.0001). Tumor location had no significant associations with the remaining parameters, including mucin production, perineural invasion, blood/lymphatic vessel invasion, lymphocytic infiltration, histologic grade, tumor stage, gross appearance, age, and gender. CONCLUSIONS: The unequal distribution of ploidy suggests distinct pathogenetic mechanisms at proximal and distal sites.

Primary diffusely infiltrative adenocarcinoma of the colon and rectum.

BACKGROUND: Primary diffusely infiltrative colorectal adenocarcinoma is rare. About 100 cases have been reported in the literature. The mucosal alterations in this type of tumor and their clinicopathological characteristics in relation to survival are not clear. METHODS: We retrospectively reviewed 30 cases of primary diffusely infiltrative colorectal adenocarcinoma operated upon in a single institution. RESULTS: Eighteen (60%) of these 30 patients were women. The average age at diagnosis was 47.4 (SD, 19.3) years. Eighteen tumors (60%) were located in the rectum. The tumors could be classified into two major types. A type 1 tumor had minimal mucosal alteration and no discrete ulcer. A type 2 tumor was associated with a discrete ulcer. The type 1 tumor was more frequently associated with intracellular or extracellular mucin production and stage IV disease. Hematogenous spread (including peritoneal carcinomatosis) was more frequently seen in type 1 than in the type 2 tumors (61% vs. 18%, p = 0.013). The overall median cancer-specific survival time was 15 (SE, 3; 95% confidence interval, 10-21) months. TNM stage is the only significant factor in predicting outcome (p = 0.016). When compared with stages II and III, the odds of death for stage IV was 2.9 (95% confidence interval: 1.1-7.4). CONCLUSION: Diffusely infiltrative colorectal cancer can be separated into two subtypes according to the presence of a discrete ulcer. The type 1 tumor (without a discrete ulcer) was associated with a higher frequency of hematogenous spread. TNM Stage was the only important clinicopathological factor in determining outcome.

Hemorrhoidectomy with self-retaining retraction.

Hemorrhoidectomy is one of the most effective treatments for significantly symptomatic hemorrhoids. By placing the patient in the Sims' position and appropriately using the Hill-Ferguson retractor and towel clip, the surgeon can get good exposure and perform a Ferguson closed hemorrhoidectomy without any assistance.

Resection of liver metastases from colorectal cancer: are there any truly significant clinical prognosticators?

PURPOSE: This study was designed to evaluate the prognostic significance of various prognostic factors affecting recurrence after resection of colorectal hepatic metastases. PATIENTS AND METHODS: Records of 54 patients who had hepatic resection between 1986 and 1993 for metastatic liver tumor from colorectal cancer were reviewed. Factors analyzed were those reported to be of prognostic significance in other studies, including gender, primary tumor site, Dukes stage, diagnostic interval, grade, preoperative carcinoembryonic antigen (CEA) level, number of metastases, size of metastases, distribution of metastases, type of resection, resection margin, and estimated blood loss. RESULTS: Average follow-up of surviving patients was 28 (range, 12-89) months. Average survival time from date of hepatic resection was 26 months, with an estimated actuarial survival rate of 25.5 percent at five years. Using the multivariate analysis of factors, gender and preoperative CEA level were shown to be significantly related to overall survival (P = 0.0455 and 0.054, respectively). Cancer of the right side colon had significant correlation with hepatic "recurrence" (P = 0.0071). CONCLUSIONS: Female patients and those with peroperative CEA values higher than 20 ng/ml have a better chance of survival following hepatic resection. Cancer of the right colon has a greater tendency for hepatic recurrence than that of the left colon.

Prognostic evaluation of DNA flow cytometric and histopathologic parameters of colorectal cancer.

BACKGROUND: The clinical value of DNA flow cytometry of colorectal cancer is unclear. The purpose of this retrospective study was to evaluate the relationship between tumor flow cytometry, histopathologic parameters, and survival. METHODS: Flow cytometry was performed on paraffin embedded specimens from 653 patients who had surgery from 1980 to 1983. RESULTS: Aneuploidy was associated with distal tumor, perineural invasion, desmoplastic reaction, and failure to secrete mucin. TNM Stage I tumors were more frequently diploid than were more advanced tumors (71% vs. 41%). An abnormal DNA content had a marginal impact on survival as evaluated by univariate analysis (69% vs. 61% 10-year survival rate, P = 0.06). Multivariate analysis revealed that significant predictors of outcome were lymph node metastasis (95% confidence interval of relative risks of death from recurrent disease, 1.50-2.92), rectal cancer (1.22-2.19), absence of lymphocytic infiltration (1.20-2.17), invasion through bowel wall (1.17-3.13), lymphatic vessel invasion outside bowel wall (1.05-2.69), perineural invasion (1.15-3.19), and male gender (1.00-1.79). CONCLUSIONS: These findings suggest that ploidy is associated with some histopathologic parameters, but flow cytometry does not correlate with long term survival of patients with colorectal carcinoma.

Presacral tumor: a review of forty-five cases.

Forty-five patients with primary presacral tumors underwent their treatment at Division of Colon Rectal Surgery, Chang Gung Memorial Hospital, from 1978 to 1992. These 45 patients, 20 male and 25 female, ranged from 15 to 76 years of age (mean, 41.1 years). Congenital tumors (47 per cent) were the most frequent histologic type, followed by miscellaneous tumors (36 per cent). Forty-eight per cent of patients had malignant tumors. All benign congenital cysts were in females. These tumors presented a variety of symptoms and signs. Diagnosis could be made by digital examination in 43 (96 per cent) of the patients. Computed tomographic scan was the most important diagnostic tool in determining the extent and degree of tumor invasion. The positive rate was 100 per cent in 21 patients. As for operative methods, abdominal approach was selected in 24 patients, transacral in 13 patients, abdominal/sacral combined in 6 patients, and biopsy only in two patients. Postoperative complications occurred in 16 patients (36 per cent), but there were no operative deaths. Of the tumors that underwent resection, 23 had total resection (18 benign and 5 malignant) and 22 incomplete (5 benign and 17 malignant). Benign tumors had a good chance with resection of the lesion (P < 0.05). For patients with malignant tumors, the 5-year survival rate was 40.7 per cent. Whenever possible, total resection could offer better results for presacral tumor, whether the lesions were benign or malignant.

An alternative treatment of anal squamous cell carcinoma: combined radiotherapy and chemotherapy.

The conventional surgical treatment of anal squamous cell carcinoma is abdominoperineal resection. A new approach of combined radiotherapy and chemotherapy has been proposed following the observation of excellent local control. In this retrospective study, 40 cases of primary anal squamous cell carcinoma without distant metastasis were collected between 1979 and 1986 and the individual prognosis of the above two methods of treatment was evaluated. Group I (20 cases) received abdominoperineal resection with or without postoperative radiotherapy. Postoperative radiation was given if regional lymph node biopsy was positive. Group II (20 cases) received combined radiotherapy and chemotherapy with or without wide local excision. Radiation was delivered to the anus, pelvis, and bilateral inguinal nodal areas to a total dose of 5,500 rads. A continuous infusion of 5-FU was started on day 2 of the irradiation at a dose of 1,000 mg/m2 body surface/day for 5 days and a bolus injection of mitomycin was given on day 2 at a dose of 10 mg/m2 body surface. The second course was given 1 month later to complete the chemotherapy. The wide local excision was performed if the disease still persisted after completion of combined radiotherapy and chemotherapy. All 40 cases were followed up for at least 5 years. All cases (100%) in group I survived 1 year, 18 cases (90%) 2 years, 14 cases (70%) 3 years, 10 cases (50%) 4 years, and 6 cases (30%) 5 years. Twenty cases (100%) in group II survived 1 year, 17 cases (85%) 2 years, 13 cases (65%) 3 years, 8 cases (40%) 4 years, and 5 cases (25%) survived 5 years. All the mortalities in both groups died of distant metastasis or abdominal carcinomatosis. From the above results, the overall survival rate of combined radiotherapy and chemotherapy was not significantly worse than that of conventional abdominoperineal resection. In conclusion, combined radiotherapy and chemotherapy may be chosen as an alternative management in treating anal squamous cell carcinoma.

Pelvic peritoneal reconstruction to prevent radiation enteritis in rectal carcinoma.

Some patients with rectal cancer who undergo exenterative surgery may require radiation therapy as an adjuvant treatment for recurrent or residual disease. A common devastating side effect of this treatment modality is radiation enteritis, a radiation-induced small bowel injury. Hence, the prevention of such a complication is essential for both the surgeon and the radiation oncologist. A new surgical method using the posterior rectus sheath and peritoneum to partition the abdominal cavity at the level of the umbilicus to the sacral promontory seems to accomplish this purpose, keeping the small bowel away from the pelvic cavity. After removal of the rectal lesion [eight abdominoperineal resections (APRs), nine Hartmann's procedures, and one low anterior resection (LAR)] in 18 patients with rectal cancer, this new surgical procedure was performed. One of the patients had an early postoperative intestinal obstruction, and all but one of the patients received postoperative adjuvant radiation therapy. In addition, a small bowel series was performed before the radiation therapy and six months and one year after surgery. Upon examination, most of these patients still had their small bowel kept intact in the abdominal cavity. During the follow-up period of 10 months to 2 years with an average of 18 months, two late complications of intestinal obstruction were noted. Exploratory laparotomy of these two patients revealed radiation enteritis of the small bowel. Therefore, the failure rate of the following procedure is 12 percent, since 2 of the 17 patients received small bowel injury. Although the follow-up period for this surgical method is short, the results have encouraged us to continue the use of this procedure on advanced rectal cancer patients who require postoperative radiation therapy.

[The clinic diagnostic value of the rigid sigmoidoscopy].

Rigid sigmoidoscopy is beneficial as it detects rectal or distal sigmoidal lesions very efficiently and precisely. But it also has some complications, e. g. rectal injury, rectal perforation or transient bacteremia. In this prospective study, 800 cases were collected and divided into two groups. In group I, 400 O.P.D. symptomatic cases were chosen randomly and in group II 400 cases registered for routine physical examination were picked up. The positive detection rate was 7% in group I versus 2% in group II. The lesions detected in group I are 15 cases of cancer, 7 cases of polyp, 4 cases of irradiation proctitis, 2 cases of ulcerative colitis and 1 case of pseudomembranous colitis. Only 8 polyps are found in group II. The routine sigmoidoscopy is mandatory for symptomatic patients but it is not cost-effective for routine check-ups. The stool occult blood is the best screening test for detecting colorectal lesions. For routine physical examination, stool occult blood test is safe and easy to perform. If the stool occult blood test is positive, then further examinations will be necessary.