University:
Stanford University
Course:
MED 101 | Human Anatomy
Academic year:

2023
Views:

331

Pages:

2
Author:

larbi43100

‭Genetic/other factors‬ ‭They are indisputable, because a patient with colorectal cancer has, in 25% of‬ ‭cases, one or more family history of the same nature. Certain clinical forms are‬ ‭clearly recognized as hereditary diseases:‬ ‭-‬ f‭amilial rectocolic polyposis, an autosomal dominant disease, linked to‬ ‭a deletion on chromosome 5. Thousands of polyps can then be‬ ‭counted in the colon, and malignant transformation, almost‬ ‭systematic, occurs before the age of 40;‬ ‭ ereditary non-polyposis colon cancer, or Lynch syndrome (autosomal‬ h ‭dominant transmission), due to a mutation of the hMSH2 genes on‬ ‭chromosome 2 and hMLH1 on chromosome 3. This syndrome is‬ ‭commonly associated with ovarian or breast cancer. endometrium in‬ ‭women;‬ ‭-‬ ‭Gaerdner syndrome, which combines other soft tissue and bone‬ ‭tumors;‬ -‭ ‬ ‭Turcot syndrome, which involves tumors of the central nervous‬ ‭system.‬ ‭-‬ ‭-Smoking (from the age of 35, but we have no biological explanation),‬ ‭alcoholism, bacteremia‬‭Streptococcus bovis‬‭(endocarditis,‬‭septicemia: the‬ ‭mechanism is unknown) and ureterosigmoidostomies (risk of almost 10% 30‬ ‭years after the operation) are also risk factors. Although indirectly, a sedentary‬ ‭lifestyle can also be incriminated: in fact, physical exercise reduces intestinal‬ ‭transit time, thus reducing the contact time between carcinogens contained in‬ ‭fecal matter and the colonic mucosa.‬ ‭Colorectal cancer is an adenocarcinoma in 98% of cases. It is located on‬ ‭the cecum and the ascending colon (25% of cases), the rectum and the‬ ‭distal sigmoid colon (25%), the descending colon and the‬ ‭proximal sigmoid (25%), or elsewhere (25%). For unknown reasons, right‬ ‭colonic localization is more common in blacks than in whites.‬ ‭Metastases are mainly to the liver, lungs and bones.‬ ‭The warning signs of colorectal cancer are late. These are mainly transit‬ ‭disorders (diarrhea, constipation, or alternation of the two), small but repeated‬ ‭digestive hemorrhages (responsible for microcytic hypochromic anemia) and‬ ‭abdominal pain (particularly when they give way due to a collapse). gas or‬ ‭stools).‬ ‭Transit disorders occur later in cancers of the ascending colon because, as the‬ ‭stools are still very liquid, the occlusive risk is low.‬ ‭Other manifestations may be added depending on possible‬ ‭metastases.‬ ‭Colonoscopy with biopsy confirms the diagnosis. The extension assessment‬ ‭(chest x-ray, abdominal CT and ultrasound, etc.) allows the classification of the‬ ‭tumor.‬