case 6.2 (hereditary colorectal cancer)
TRANSCRIPT
CASE 6.2: HEREDITARY COLORECTAL CANCER.
Presenter: Arwa Al-Onayzan.ID: 215007943.
www.cityofhope.org
Our case: Saher (35 year old women) who is consulting her GP because:She regularly has intestinal problem.She has an enquiry about screening test.• She is worried about herself and her children.
Her aunts died of colorectal cancer at age 54.Her father had six intestinal polyps.Her grandmother had uterine problems and died at age 48.
Objectives: Can the colorectal cancer be inherited?
The pedigree of the patient in this case.
Inherited colorectal cancer conditions.
- Which gene can be affected in hereditary colorectal cancer?
The mechanism of mismatch repair gene.
The screening and who is recommended to do it ?
Types of prevention of the hereditary cancer.
The incident of colon cancer in KSA.
How to handle this case?
Can the colorectal cancer be inherited?
• Yes, it can be inherited when several generations of a family have colorectal cancer.
• Several gene mutations that cause colorectal cancer, it can be transmitted to family members.
https://familysearch.org/blog/en/family-health-history-2/
The pedigree of the patient in this case.
What does that mean?• There is a family history for colorectal cancer.• It could mean the potential for developing colorectal
cancer has been passed from one generation of the family to the next generation.
Inherited colorectal cancer syndromes
• The 2 most common inherited colorectal cancer
syndromes are:
- Hereditary nonpolyposis colorectal cancer (HNPCC)-
Lynch syndrome.
- Familial adenomatous polyposis (FAP).
familyhistorybowelcancer.wordpress.com
Lynch syndromeThe most common form of hereditary CRC.
It is inherited as an autosomal dominant syndrome.
A result of defective mismatch repair (MMR) gene.
Typically have small number of polyps.
Lynch syndromePeople with this condition have an 80% riskof developing CRC.
Increased risk for certain cancers, including :tumors of the uterus and small intestine.
Familial adenomatous polyposis (FAP)
• Rare condition.• Presence of more than 100 or even 1000 of benign polyps.• It is an autosomal dominant inherited disorder.• Mutation in APC suppressor gene. • Normally it promotes apoptosis in colonic cells.
The patient in our case most likely to have………
• Because:
#It causes all the types of abnormalities that mentioned in the case: • Aunt: colorectal cancer . Age 54.• Grandmother: Uterine problems. Age 48.• Father: six intestinal polyps.
lynch syndrome.
The mechanism of mismatch repair gene
• Mismatch error means that:• C is paired with A rather than G or G paired with U rather than C.
• Aim: remove and correct replication errors.
• Deficient mismatch repair gene is a common etiologic factor for colorectal cancer.
The mechanism of mismatch repair gene
Source: ESSENTIAL CELL BIOLOGY.
Who is recommended to do screening ?
Colonoscopy
-Examination of the colon by using a colonoscope.
-Flexible tube inserted into the body that allows doctors to view the interior of the colon.
Prevention of hereditary cancer
Chemoprevention drugs.
news.bbc.co.uk
Changes in lifestyle factors.
Prophylactic surgery.
Screening test
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The incident of colorectal cancer in KSA.
The incident of colorectal cancer in KSA:
Ranking first among male (9%)
Ranking third among female (10%)
# CRC is the second most common cancer in KSA.
How can we explain to Sahar this situation
and satisfy her?
How can we handle this case? Explain that to her by using the pedigree because:- It is preferred method of collecting family history information. - Effective and visual. - Easier and quicker.
Advise her to do the screening.
Make examination for her intestine and find out the
problem.
How can we handle this case? Give her information about colorectal cancer and how
she can prevent herself and her children by - Eat balance diet .- Exercise.- Reduce radiation exposure .- And so on .
Summery
# we talked about:
The pedigree of the patient in this case.
Inherited colorectal cancer syndromes and gene they affect.
The mechanism of mismatch gene.
The screening and who is recommended to do it ?
Types of prevention of the hereditary cancer.
The incident of colorectal cancer in KSA.
Handle the case.
Any Question?
References• FORCE website (Hereditary Cancer).• WebMD website (Inherited Colorectal Cancer).• PubMed website (Screening for germ line mutations• by Bracko M).• ESSENTIAL CELL BIOLOGY BOOK (FOURTH EDITION).• MEDICAL GENETICS BOOK (FOURTH EDITION).• Robbins BASIC PATHOLOGY (NINTH EDITION).• American cancer society(2013) (Genetic Testing for Cancer :
What You Need to Know, American cancer society.16)• PubMed website (Public Awareness of Colorectal Cancer in
Saudi Arabia: A Survey of 1070 Participants in Riyadh by Ahmad M. Zubaidi, Noura M. AlSubaie).