Primary malignant tumors (cancer) of the colon are quite common. In France, more than 40,000 new cases are diagnosed each year, so this is the most common cancer in France.
Most often, the transformation of a benign tumor (adenomatous polyp) leads to cancer. This cancer can be detected using an immunological test. A mass examination is usually offered to women and men aged 50 to 74 years every 2 years.
Risk factors include a personal history of colon or colorectal cancer, a family history of first-degree colorectal cancer, inflammatory bowel disease, and genetic factors (familial adenomatous polyposis, Lynch syndrome, or HNPCC). A preventive measure consists of regular observation by a gastroenterologist and regular colonoscopy. Certain foods, when consumed in excess, contribute to the development of colorectal oncology, in particular red meat.
Clinical signs may include worsening general condition (weight loss), abdominal pain, melena (digestive hemorrhage), rectal bleeding, microcytic anemia, and transitory disorders (diarrhea).
Some tumors can lead to colon occlusion. Signs of colon obstruction are severe abdominal pain, vomiting, gas and stool stopping, bloating, and dehydration. Diagnosis consists of a total colonoscopy to examine the entire inner wall of the colon, which is performed by a gastroenterologist. The scanner of the chest, abdomen and pelvis with an injection of iodine contrast agent allows you to localize the tumor and evaluate local, regional (lymph node damage) as well as distant (for example, metastases in the lungs and liver). Sometimes liver MRI is done to better visualize the organ in case of doubt of secondary involvement. A blood test for tumor markers ACE and CA 19-9 is also mandatory.
Treatment of a colon tumor involves surgical resection of the part of the colic where the lesion, lesions and lymph nodes are located. The operation can be performed using laparoscopy or laparotomy, performed by a gastro surgeon.
Tissue analysis is performed directly in the operating room. In some cases, a stoma is necessary (evacuation of stool in a special pocket attached to the stomach), it may be a temporary solution. The main variety of colon tumors is Lieberkühn adenocarcinoma. Depending on the stage of the tumor and the type of cancer (molecular profile, MSI status), adjuvant chemotherapeutic treatment may be offered, at stage II or III, 3 months of the XELOX or CAPOX protocol: 5-fluorouracil or capecitabine + folinic acid + oxaliplatin), if poor prognosis is discovered, adjuvant chemotherapy lasts 6 months (FOLFOX protocol: 5-fluorouracil + folinic acid + oxaliplatin). In the case of a metastatic attack, a mutation search in the KRAS, NRAS, BRAF genes is carried out. Since the KRAS and NRAS proteins are located below the EGF receptor signaling pathway, their mutations do not allow effective treatment with targeted anti-EGFR therapy.
The most commonly used treatment protocols are chemotherapy for metastatic lesions such as FOLFOX, FOLFIRI (5-fluorouracil combined with folinic acid, irinotecan) and targeted therapy anti-EGFR or a VEGF receptor inhibitor (bevacizumab, blocking neovascularization).