Familial Gastric Cancer Flashcards
What are the major risk factors for developing gastric adenocarcinoma?
Heliobacter pylori infection
smoked/processed foods
obesity
alcohol/tobacco use
long-term inflammation
gastroesophageal reflux disease
What percentage of gastric adenocarcinoma cases have a familial predisposition?
Up to 10%.
How is “familial gastric cancer” defined?
Having two first- or second-degree relatives with gastric cancer diagnosed before age 50
or three first- or second-degree relatives diagnosed at any age.
Besides adenocarcinoma, what other types of gastric cancer exist?
Primary gastric lymphoma (2%–8%)
gastrointestinal stromal tumor (<1%)
neuroendocrine tumor (<1%)
What are the two histological subtypes of gastric adenocarcinoma according to the Lauren classification?
Intestinal and diffuse subtypes.
What is a key characteristic of the intestinal subtype of gastric adenocarcinoma?
Tumor cells are arranged in a glandular formation.
What are common associations with the intestinal subtype of gastric adenocarcinoma?
Environmental risk factors and a more favorable prognosis.
What distinguishes the diffuse subtype of gastric adenocarcinoma histologically?
Lack of adhesion molecules and poorly cohesive cells.
Why does the diffuse subtype of gastric adenocarcinoma have a poor prognosis?
It is highly metastatic, associated with transmural, poorly differentiated lesions, and is common in younger patients.
What percentage of all gastric cancers is accounted for by Hereditary Diffuse Gastric Cancer (HDGC)?
About 1% to 3%.
Which gene mutation is associated with HDGC, and where is it located?
A loss-of-function mutation in the CDH1 gene on chromosome 16q.
What is the role of the CDH1 gene, and how does its mutation contribute to cancer?
CDH1 encodes a cell-cell adhesion protein; loss of function increases invasiveness and promotes epithelial-to-mesenchymal transition
What types of cancer are individuals with a CDH1 mutation at higher risk of developing?
Diffuse, aggressive, signet ring gastric adenocarcinoma, and lobular breast carcinoma
or cleft lip and palate
What additional conditions are associated with CDH1 mutation in HDGC families?
Up to 60% of women may develop lobular breast cancer, and about 14% of families report cleft lip and palate.
At what age is CDH1 genetic testing recommended to begin, according to the IGCLC?
Testing is recommended to begin at 18 years of age.
When should asymptomatic family members with HDGC history consider genetic testing?
5 years before the earliest age of cancer diagnosis in the family or in their second decade of life.
Family Criteria (First- or Second-Degree Blood Relatives)
1
Individual Criteria
2
cont
3
At what average age do patients with Hereditary Diffuse Gastric Cancer (HDGC) typically develop poorly differentiated diffuse gastric cancer?
By around 38 years of age
Why is prophylactic total gastrectomy (PTG) recommended for asymptomatic CDH1 mutation carriers?
PTG offers excellent primary prevention outcomes against gastric cancer in HDGC patients.
What preoperative evaluations are essential before PTG in HDGC patients?
Nutritional assessment
discussion of surgical risks
and counseling on long-term dietary changes
What is the protocol for HDGC patients who decline PTG
Annual endoscopic surveillance starting at age 20
with multiple biopsies of visible lesions
and 30 random biopsies from all five stomach zones.
Why is endoscopic surveillance limited in detecting early diffuse gastric cancer in HDGC patients?
Diffuse gastric cancer can infiltrate the submucosa without visible lesions, resulting in a high false-negative rate.
What percentage of CDH1 mutation carriers show T1N0 malignancy upon prophylactic gastrectomy?
92% of patients have T1N0 malignancy, while only 16% were detected through endoscopic surveillance
What additional cancer risk do female CDH1 mutation carriers face?
A high lifetime risk of lobular breast cancer.
What surveillance is recommended for CDH1 mutation carriers at risk for lobular breast cancer?
Annual mammography or breast MRI starting at 30 years of age.
When might bilateral prophylactic mastectomy be considered for CDH1 mutation carriers?
Between 30 and 60 years of age, especially with a family history of multiple cases of lobular breast cancer.
Who should be included in the multidisciplinary team managing HDGC patients?
A surgical oncologist, gastroenterologist, dietician, pathologist, and genetic counselor
What genetic mutations are associated with Lynch syndrome?
Germline mutations in mismatch repair (MMR) genes MLH1, MSH2, MSH6, and PMS2
How does Lynch syndrome contribute to carcinogenesis in organs other than the colon?
MMR gene mutations lead to DNA microsatellite instability, affecting organs like the stomach, uterus, ovaries, and hepatobiliary system.
Which MMR gene mutations are responsible for 90% of microsatellite instability in CRC associated with Lynch syndrome?
Mutations in hMSH2 (chromosome 2p) and hMLH1 (chromosome 3p).
What is the approximate incidence of gastric malignancy in patients with Lynch syndrome?
4% to 8%.
At what age do Lynch syndrome patients with gastric cancer typically present?
Generally before the age of 50.
Which gastric cancer phenotype is most common in Lynch syndrome patients?
The intestinal phenotype.
Who should undergo endoscopic surveillance for gastric cancer in the context of Lynch syndrome?
Patients with HNPCC and a family history of gastric cancer, or carriers of MLH1/MSH2 mutations.