Talking about cancer is scary! On the list of common cancers, the incidence of colorectal cancer has jumped to the 3rd to 5th place, becoming the “dark horse” of the cancer world. Some colorectal cancers can also be hereditary! Colorectal cancer is no longer a matter of the elderly, but can be found in the age of 20, 30 and 40.
Mr. Lin” is an impatient person
”Mr. Lynch syndrome is an autosomal dominant genetic disorder caused by germline mutations in the mismatch repair gene (MMR). This “Mr. Lynch” is an acute and abominable guy, what does this mean?
(1) Early age of onset, median age is about 44 years, and the time required to progress from adenoma to adenocarcinoma is relatively short, from 8 to 10 years in normal individuals, but only 2 to 3 years in patients with Lynch syndrome.
(2) It is more common in the proximal segment of the colon, with about 70% located proximal to the splenic flexure.
(3) Significant increase in multiple primary colorectal cancers.
(4) high incidence of extraintestinal malignancies, simultaneous and heterochronic multiple primary cancers such as endometrial cancer, ovarian cancer, gastric cancer, intrahepatic bile duct cancer, urinary tract tumors and skin cancer significantly higher than the normal population – many tumors have to be mixed in, abominable enough
(5) Hypofractionated adenocarcinoma and mucinous adenocarcinoma are common and are accompanied by lymphocytic infiltration or aggregation of lymph-like cells.
(6) Vertical inheritance and familial aggregation – vernacular manifestation.
(7) Mostly swelling growth rather than infiltrative growth. The prognosis is better – this is a bit of conscience and does not drive the disease to extinction.
FAP in name only
Familial adenomatous polyposis (FAP) is an autosomal dominant disorder caused by an APC mutation. The best thing this member of the “polyp” family can do is to grow polyps everywhere to identify himself. Those who are intensely phobic may be stunned by his presence – the intestines are filled with polyps ranging from tens to hundreds or even thousands. Common symptoms include diarrhea, abdominal pain, and blood in the stool. Patients often suffer from anemia and weight loss due to prolonged exertion during the tug-of-war. The seriousness of the disease lies in the high rate of carcinoma, which is often not limited to one location but is “multicentric”. Adenomatous polyps can appear at the age of 12 or 13, and by the age of 20 the polyps have spread throughout the large intestine.
The low-profile and sinister MAP
MUTYH-associated polyposis (MAP) is an autosomal recessive disorder caused by mutations in the MUTYH gene, which is very similar to familial adenomatous polyposis, and is a low-profile and insidious disease, with no APC mutations in genetic testing and no tumor microsatellite instability. However, when this guy shows his fangs, the victims are more at risk – patients with MUTYH mutations have a significantly higher risk of colorectal cancer.
Other members
1.Gardner syndrome (GS)
It is a rare autosomal dominant disorder with three major features: colorectal polyposis, combined multiple osteomas and soft tissue tumors.
2. Gliomatous polyposis syndrome
It is a clinically rare clinical subtype of FAP, characterized by familial multiple colonic adenomas with central nervous system malignancies.
3.Polypsis nigricans
Polyposis nigricans (PJS) is associated with mutations in the SKT11 gene. The three main clinical features are skin mucosal discoloration, gastrointestinal misshapen polyps and family inheritance. Typical cutaneous mucosal dark spots and/or intussusception, intestinal obstruction or bleeding may occur during childhood. The risk of polyp malignancy increases with age. Polyps can appear throughout the intestinal tract. However, polyps do not stay in the intestine, they can also appear outside the intestine, such as in the bladder and respiratory tract.
4. Familial Juvenile Polyposis (FJIPC)
Autosomal dominant, mainly associated with mutations in SMAD4 or BMPR1A gene. FJIPC also has the “virtue” of “helping cancer”, which can significantly increase the risk of colorectal, small bowel, gastric and pancreatic cancer. Some patients with familial juvenile colonic polyposis may have congenital disorders such as pestle and mortar finger (toe), hypertrophic pulmonary osteoarthropathy, hydrocephalus, cleft lip, cleft palate, congenital heart disease, etc. Carriers of SMAD4 mutation sometimes develop hereditary associated capillary hemorrhage, which manifests as recurrent rhinorrhea, dilated skin mucosa or lung capillaries, and arteriovenous malformation of brain or liver.
5. PTEN malformation syndrome (PHTS)
PTEN is an autosomal dominant disorder caused by mutations in the PTEN gene, including Cowden syndrome and BRRS syndrome, which manifests as colorectal polyposis with multiple malformations, facial papules, acromegaly and oral mucosal papillomas. BRRS syndrome is also an autosomal dominant disorder caused by PTEN mutations and is characterized by colorectal polyposis, macrosomia, lipomatosis, hemangiomatosis and genital discoloration.
How to prevent hereditary colorectal cancer
Three early: early detection, early diagnosis and early treatment.
1.Early colonoscopy.
2.Genetic testing.
3.Genetic counseling.