PubMed Health⌕ Search

Biomedical subjects

P Sherlock

Publications and source records attributed to P Sherlock.

At least 19 recordsLinked to original sources
PubMed1987

Screening for colorectal cancer in a high-risk population. Results of a mathematical model.

A mathematical model was used to estimate the cost-effectiveness of colorectal cancer screening strategies for people who are at high risk because of a first-degree relative with colorectal cancer. The model uses indirect evidence about such factors as cancer incidence, sensitivity and specificity of different tests, and treatment effectiveness. The analysis indicates that for screening people over 40 yr old an annual fecal occult blood test may reduce colorectal cancer mortality by about one-third, either colonoscopy or barium enema may reduce mortality by approximately 85%, a 3-5-yr frequency for endoscopies or barium enemas preserves 70%-90% of the effectiveness of an annual frequency, and beginning screening at age 50 reduces effectiveness by 5%-10%. Although both barium enemas and colonoscopies appear to be effective in reducing mortality, the lower cost of the barium enema makes it a more cost-effective strategy. All of these estimates depend on the baseline estimates of each of the factors incorporated in the model; the conclusions are most sensitive to assumptions about the natural history of adenomatous polyps, the bleeding of adenomas and presymptomatic cancers, and the sensitivity of the fecal occult blood test. Recommendations about colorectal cancer screening must also consider factors such as discomfort, inconvenience, and the availability of various technologies.

Colonic Neoplasms↗
PubMed1985

Gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine: role of gastrectomy and duodenal reflux.

The effect of gastrectomy and duodenal reflux on gastric carcinogenesis was studied because gastrectomized patients may be considered at "high risk" for the development of gastric stump cancer. Wistar rats received N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) (83 mg/liter) ad libitum in the drinking water for either four, eight, or twelve weeks. A control group received tap water. After MNNG administration animals were antrectomized. Antrectomy was not performed in a control group. Bowel continuity was restored either with a Billroth II (BIL) or with a ROUX en Y (ROUX) procedure. Duodenogastric reflux is possible after the BIL but not after the ROUX procedure. Eight months after the beginning of the experiment the stomachs of the animals were studied. In both operated and unoperated animals, the number of cancers observed was significantly related to the duration of MNNG administration. Animals receiving MNNG plus the BIL procedure had a significantly higher number of anastomotic cancers than the ROUX animals, indicating that duodenogastric reflux played a promotional role in gastric carcinogenesis. Three BIL gastrectomized rats not receiving the carcinogen had an adenocarcinoma on the anastomotic line further emphasizing the risk attached to the duodeno-gastric reflux.

Animals↗
PubMed1983

Nutrition and cancer.

Nutrition and cancer interact at several levels. Both dietary deficiencies and dietary excesses have been linked with changes in prevalence of certain human cancers. With respect to one particular nutrient, riboflavin, a dietary deficiency may decrease the development of spontaneous tumors in experimental animals but increase carcinogenesis due to certain agents. Cancer itself has profound effects upon nutritional status, and neoplastic tissue appears in general to resist dietary deficiency more effectively than normal tissues. Nutrition has a major role in therapy of cancer, but as an adjunct to the treatment plan rather than as an alternative. Parenteral nutrition, either peripheral or total, can provide support that is critically needed when patients cannot eat or swallow, have obstruction or malabsorption, or are otherwise unable to utilize dietary nutrients in adequate amounts. The advent of home parenteral nutrition now provides a means for long-term rehabilitation of cancer patients.

Animals↗
PubMed1978

The value of diagnostic aids in detecting pancreas cancer.

By contract with the National Cancer Institute, the accuracy of diagnostic techniques was assessed in 184 patients suspected of having pancreas cancer. Of 138 patients who were operated upon, 89 were found to have pancreas duct cancer, 30 had cancer of a different site of origin in the head of the pancreas region and in 19 there was no evidence of cancer at operation. All of the 46 patients who were not operated upon, 13 proven to have cancer and 33 patients discharged as free of cancer, were followed in our clinic. The majority of our patients presented with signs and symptoms of biliary obstruction. Computerized transaxial tomography (CTT) gave a "correct" diagnosis in 31 of 33 patients (94%) with proven cancer, there were 2 patients with a false negative report and a false positive diagnosis occurred in 8 of 20 patients (40%) without cancer. Celiac angiography (CA) gave a correct diagnosis in 78 of 94 patients (83%) with cancer, a false negative in 17%, and a false positive in 32%. 76Selenomethionine pancreas scan correctly diagnosed 27 of 36 patients (75%) with cancer, gave a false negative in 25% and a false positive in 31%. Ultrasonography gave a correct diagnosis in 18 of 27 patients with cancer (67%), a false negative in 33% and a false positive in 28%. Endoscopic retrograde cholangiopancreatography diagnosed correctly 8 of 11 cases (73%) of cancer, there were false negative diagnoses in 3 cases (27%) and false positives in 3 of 14 patients (21%). Duodenal aspiration techniques gave a very low percentage of correct diagnoses. Chronic pancreatitis most commonly gave rise to a false positive diagnosis. Serum alkaline phosphatase was elevated in 82% of patients, gave 18% false negatives and 33% false positives. Carcinoembryonic antigen (CEA) was elevated (greater than 2.5 ng/ml) in most of the pancreas cancer patients but also in patients with other cancers and with non-cancerous diseases. In our hands, CTT, CA, alkaline phosphatase, 75Se-methionine and ultrasonography, in descending order, have given the highest percentage of correct diagnoses but false positive and false negative diagnoses prevented any single test from being conclusive.

Biopsy, Needle↗
PubMed1978

Colonoscopic biopsy and cytology in the diagnosis of colon cancer.

Colonoscopy has revolutionalized the approach to the diagnosis and management of patients with colorectal neoplasia. When malignant-appearing lesions are visualized by colonoscopy, a variety of diagnostic techniques are currently available for the assessment of the nature of the lesion including biopsy, brush cytology, and lavage cytology. Comparison of results for biopsy alone with biopsy plus either or both cytologic techniques showed a positive yield of 60% for biopsy alone; 76% for biopsy and lavage; 89% for biopsy, brush, and lavage. When the cancers were divided into infiltrative and exophytic lesions the positive yield for biopsy alone was 33% for infiltrative, cancer, and 71% for exophytic cancer; for biopsy and lavage cytology, 44% for infiltrative cancer, and 94% for exophytic cancer; for biopsy and brush cytology, 78% for infiltrative, and 94% for exophytic cancer; and for biopsy, brush, and lavage cytology, 83% for infiltrative cancer, and 92% for exophytic cancer. The use of brush cytology improved the yield of tissue diagnosis considerably when added to the biopsy technique. Lavage cytology did not seem to increase significantly the diagnostic yield. The diagnostic yield of the various techniques was related not only to the specific combination of techniques used, but also to the gross tumor pattern.

Adenocarcinoma↗
PubMed1977

Feasibility of fecal occult-blood testing for detection of colorectal neoplasia: debits and credits.

A screening program for colorectal cancer and adenomas has been applied to 6,579 mostly asymptomatic men and women age 40 years and older utilizing fecal occult-blood testing followed by investigation of patients with positive slides by air-contrast barium enema and colonoscopy. A control population of 7,325 patients had sigmoidoscopy only and no occult-blood testing. Approximately 1% of the patients had positive slides; most patients had only one or two slides positive. Approximately 50% of patients with positive slides had significant neoplastic lesions, including 23 patients with large adenomas and 7 patients with cancers. Pathological staging of cancers was more favorable in the screened asymptomatic group as compared with the control group. Neoplastic lesions seen on sigmoidoscopy in screened patients who had negative fecal occult-blood tests included 2 cancers and 15 large adenomas. Reasons for false negativity include possible conversion of initially positive slides to negative. Screening for colorectal cancer and adenomas with fecal occult-blood testing appears to be feasible approach with good patient compliance, and manageable rate of positive slides productive of a high percentage of neoplastic lesions. The number of false-positives seems to be low. False negativity has been observed and will require further study.

Adenoma↗
PubMed1977

Detecting early colon cancer.

Techniques enabling detection of early colon cancer already exist, but to be more productive in terms of improving survival they must be applied in a meaningful sequence and repeated regularly in high-risk patients. Positive findings in specific screening steps based on well-known risk factors in colon cancer always call for aggressive follow-up. The advantages and disadvantages of the various techniques are discussed.

Barium Sulfate↗
PubMed1977

Carcinoembryonic antigen in colonic lavage.

Colonoscopic lavage was performed for assay of carcinoembryonic antigen (CEA) concentration in patients with small and large colonic adenomas, in patients with adenocarcinoma of the colon, and in normal controls. CEA concentration was considerably higher in colonoscopic lavage as compared to plasma. CEA concentration in normal controls and in patients with colonic adenomas less than 1 cm in size were not significantly different. CEA concentrations in patients with colonic adenomas greater than 1 cm in size and in patients with adenocarcinoma of the colon were significantly higher than those observed in patients with small adenomas and in the normal controls. In all except 2 patients, plasma CEA concentrations were normal. Assay of CEA concentrations in colonic lavage may have potential application in the further assessment of the mucosa at risk for colon adenomas and for colon cancer. It does not appear to be accurate enough for diagnosis of colon cancer in individual patients.

Adenocarcinoma↗
PubMed1976

The role of upper gastrointestinal endoscopy in patients with cancer.

The last decade has seen considerable advance in the application of fiberoptic endoscopy to the diagnosis and management of patients with cancer. Forward and side-viewing instruments have been developed that have complete tip control, potential for obtaining directed biopsies, brush and lavage cytology, and for aspiration of material for assay of enzymes and tumor-associated antigens. These features have provided a high degree of diagnostic capability in the esophagus, stomach, and duodenum. Accurate histologic diagnoses require multiple biopsies and brush cytology from each lesion. Lavage cytology has been useful in selected patients, especially those with diffusely infiltrating lesions. Brush cytology has been especially helpful in patients with stenotic esophageal cancer. These techniques have also provided a diagnosis in a high percentage of patients with lymphoma involving the stomach. Endoscopy has also been very useful in patients with nongastrointestinal cancer who have major gastrointestinal problems such as bleeding stress ulcers or monilial esophagitis.

Biopsy↗