This case discusses a 35-year-old woman named Saher who is concerned about her risk of colorectal cancer due to her family history. Saher's aunts died of colorectal cancer at age 54, her father had intestinal polyps, and her grandmother had uterine cancer and died at age 48. The document discusses that colorectal cancer can be inherited through gene mutations. It explains that Saher most likely has Lynch syndrome, the most common form of hereditary colorectal cancer caused by a defective mismatch repair gene. The document recommends screening and provides prevention strategies like diet, exercise and prophylactic surgery to help manage Saher's risk and the risks to her children.
2. 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.
3. 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?
4. 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/
6. 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.
7. 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
8. Lynch syndrome
The 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.
9. Lynch syndrome
People with this condition have an 80% risk
of developing CRC.
Increased risk for certain cancers, including :
tumors of the uterus and small intestine.
10. 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.
11. 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.
12. 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.
13. The mechanism of mismatch repair gene
Source: ESSENTIAL CELL BIOLOGY.
15. 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.
16. Prevention of hereditary cancer
Chemoprevention drugs. news.bbc.co.uk
Changes in lifestyle factors.
Prophylactic surgery.
Screening test
http://www.lifescript.comwww.blendspace.com
www.medcaredia
gnostics.com
17. 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.
18. How can we explain
to Sahar this situation
and satisfy her?
19. 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.
20. 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 .
21. 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.
24. 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).
Editor's Notes
# One of the risk factors for colorectal cancer is a family history of the disease.
- One of the risk factors for colon cancer is a family history of the disease.
- a person who has a family history of colon cancer and eventually develops the disease is more likely to have inherited the cancer gene than a person with no family history of colorectal cancer.
The pedigree illustrates the relationships among family members, and it shows which family members are affected or unaffected by a genetic disease. It is used manly in medical genetics.
(HNPCC) “known as Lynch syndrome”
http://emedicine.medscape.com/article/188613-overview Lynch syndrome families may include individuals with other gastrointestinal and gynecologic cancers
http://emedicine.medscape.com/article/188613-clinical
has a high risk of colon cancer[1] as well as other cancers including endometrial cancer (second most common), ovary, stomach, small intestine, hepatobiliary tract, upper urinary tract, brain, and skin.
the following signs and symptoms may develop as the cancer advances:
Changes in bowel habits (eg, constipation or diarrhea that persists for longer than several days)
Visible or occult blood in stool (positive fecal occult blood test)
Black, tarry stool (may represent bleeding above the rectum)
Iron deficiency without an identifiable cause
signs and symptoms may develop as the cancer advances:
Changes in bowel habits (eg, constipation or diarrhea that persists for longer than several days)
It’s an autosomal dominant of germ line mutation in APC suppressor gene
Normally it promotes apoptosis in colonic cells and inactivate B – catenin which promotes transcription of proto- oncogene genes
So when APC is mutated apoptosis of colonic cells will be reduced
allows b-catenin to accumulate intracellularly and to stimulate cell growth, the consequence is development of adenomas in colon
It’s an autosomal dominant of germ line mutation in APC suppressor gene.
Normally it promotes apoptosis in colonic cells and inactivate B – catenin
which promotes transcription of proto- oncogene genes.
Cause : escape of the proofreading function of DNA polymerase during DNA synthesize.
Result: permanent mutation in the next round of DNA replication
Deficient DNA mismatch repair: a common etiologic factor for colon cancer
Mismatch or mispaired nucleotides.
Errors at DNA replication are corrected via the DNA mismatch repair pathway ... rise touncorrected mutations and increasing the risk of cancer.
Steps : 1/(nick= break) is formed mostly in the newly DNA strand that includes incorrect matched base
2/ this nick will be as signal that allow (mismatch repair protein ) to distinguish the newly synthesized DNA ( which contain mistakes) from the old, normal DNA strand
3/ short sequence in newly synthesized DNA strand including the mismatched nucleotide is removed by ( mismatch repair protein )
4/ gap left in newly synthesized DNA strand filled by DNA polymerase using the sister strand as template
5/ DNA ligase join the correct sequence with original of newly synthesized DNA..
In general, individuals can be divided into different risk profiles. A simplified schema is provided below.
Screening is looking for cancer before a person has any symptoms.
This can help find cancer at an early stage.
When abnormal tissue or cancer is found early, it may be easier to treat. By the time symptoms appear, cancer may have begun to spread.
We do it to check if the person have polpys cuz this polps could lead to cancer.
Chemoprevention: using of medicines to prevent cellsfrom developing into certain types of cancer.Several medicines reduce the risk of certain cancers, Example : the drugs tamoxifen and raloxifene can be used to reduce breast cancer risk
Prophylactic (preventive) surgery example : to remove the tissue thathas a high risk to be cancer.some women at high risk for ovarian cancer may decide to have their ovaries removed once they’ve had their children.
Changes in lifestyle factors example : Eating healthy food ,Exercising and limiting alcohol intake, stop smoking
Cancer detection tests and awareness Early detection tests may be started at an earlier age or be done more often. It’s important to be aware of the possible signs and symptoms of cancers you are at higher risk for.