Colorectal Cancer Overview
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Questions and Answers

What is the probability of a child inheriting the familial adenomatous polyposis (FAP) gene from an affected parent?

  • 50% (correct)
  • 10%
  • 75%
  • 25%

    • At what age is it estimated that all untreated patients with familial adenomatous polyposis (FAP) will have developed colon cancer?

  • 30
  • 40 (correct)
  • 35
  • 45

    • What type of test is commonly used to detect mutations in the APC gene associated with FAP?

  • MRI scan
  • CT scan
  • Laparoscopy
  • Genetic blood test (correct)

    • What is the recommended treatment procedure for patients diagnosed with familial adenomatous polyposis (FAP)?

    <p>Total procto-colectomy</p> Signup and view all the answers

    Which of the following is a characteristic feature of Lynch syndrome?

    <p>Increased risk of several cancer types</p> Signup and view all the answers

    What is a recommended screening procedure for detecting FAP in patients starting at age 20?

    <p>EGD</p> Signup and view all the answers

    Which of the following best describes the Bethesda criteria related to Lynch syndrome?

    <p>Developing colorectal or endometrial cancer younger than age 50</p> Signup and view all the answers

    What type of instability is commonly found in tumor specimens of patients with Lynch syndrome?

    <p>Microsatellite instability (MSI-H)</p> Signup and view all the answers

    Which of the following relatives is NOT considered a first-degree relative in the context of Lynch syndrome?

    <p>Aunt</p> Signup and view all the answers

    Which statement about colon polyps in familial adenomatous polyposis (FAP) is true?

    <p>Colon polyps can become cancerous in the teenage years.</p> Signup and view all the answers

    What is the primary precursor lesion for colorectal adenocarcinoma?

    <p>Adenomatous polyp</p> Signup and view all the answers

    Which genetic condition is associated with an extremely high risk of colorectal cancer due to a mutated gene?

    <p>Familial adenomatous polyposis</p> Signup and view all the answers

    Which pathway accounts for approximately 70% of colon cancers?

    <p>Chromosomal instability (CIN)</p> Signup and view all the answers

    What is the estimated mortality from colorectal cancer in women in 2020?

    <p>24,530</p> Signup and view all the answers

    What is the relative risk of colorectal cancer for a daily increase of 100 g of red meat consumption?

    <p>1.17</p> Signup and view all the answers

    Which type of meat is not associated with an increased risk of colorectal cancer?

    <p>White meat</p> Signup and view all the answers

    Which molecular pathway is seen in approximately 15% of sporadic colorectal cancer cases?

    <p>Microsatellite instability (MSI)</p> Signup and view all the answers

    What is the recommended daily amount of red meat for healthy individuals?

    <p>70 g</p> Signup and view all the answers

    Which of the following factors is thought to contribute to the etiology of sporadic colorectal cancer?

    <p>A combination of genetic and environmental factors</p> Signup and view all the answers

    What kind of diet is recommended to help diminish the carcinogenic effects of HCAs?

    <p>High in dietary fiber sources</p> Signup and view all the answers

    Which type of colorectal polyp accounts for 70%-85% of adenomas?

    <p>Tubular adenoma</p> Signup and view all the answers

    What is the silent potential of colonic polyps primarily concerned with?

    <p>Their ability to become malignant</p> Signup and view all the answers

    How long can the progression from adenoma to carcinoma take?

    <p>5 years or longer</p> Signup and view all the answers

    Which of the following patients typically has a genetic mutation related to Familial Adenomatous Polyposis (FAP)?

    <p>Those with a parent diagnosed with FAP</p> Signup and view all the answers

    What type of lesion is characterized by having varying dysplasia and a risk of invasion into the submucosa?

    <p>Neoplastic lesion</p> Signup and view all the answers

    What percentage of large-bowel malignancies are attributed to hereditary colorectal cancer cases?

    <p>15%</p> Signup and view all the answers

    Which treatment is typically used for hyperplastic lesions?

    <p>Surgical resection only</p> Signup and view all the answers

    What defines the histologic characteristics of gastrointestinal polyps?

    <p>Their histologic structure</p> Signup and view all the answers

    What method of cooking can help reduce the formation of HCAs in meat?

    <p>Microwave cooking</p> Signup and view all the answers

    Which of the following is not a type of adenoma according to the classification provided?

    <p>Flat adenoma</p> Signup and view all the answers

    Which of these symptoms is NOT commonly associated with potential colon cancer?

    <p>Shortness of breath</p> Signup and view all the answers

    What proportion of Familial Adenomatous Polyposis (FAP) patients develop the mutation during conception?

    <p>30%</p> Signup and view all the answers

    In a medical history inquiry for potential colon cancer, which hereditary condition should be specifically asked about?

    <p>Familial Adenomatous Polyposis (FAP)</p> Signup and view all the answers

    Which diagnostic test is preferred for diagnosing colon cancer?

    <p>Colonoscopy with biopsy</p> Signup and view all the answers

    What is the typical treatment approach for Stage I and II colon cancer?

    <p>Surgery alone</p> Signup and view all the answers

    Which of the following is an extraintestinal manifestation that should be considered in the history of a patient with potential FAP?

    <p>Desmoid tumors</p> Signup and view all the answers

    For patients with Stage III colon cancer, what type of treatment is commonly administered?

    <p>Adjuvant chemotherapy</p> Signup and view all the answers

    What could the presence of occult GI bleeding during a diagnosis indicate?

    <p>Lead to misdiagnosis due to aspirin use</p> Signup and view all the answers

    What is the main approach for treating rectal cancers?

    <p>Neoadjuvant chemotherapy followed by postoperative chemotherapy</p> Signup and view all the answers

    Which of the following is NOT a typical site for distant metastases in colon cancer?

    <p>Skin</p> Signup and view all the answers

    Study Notes

    Colorectal Cancer (CRC)

    • CRC is the third most common cancer in men and women.
    • Early detection leads to an excellent prognosis.
    • Screening average-risk individuals over 50 significantly reduces incidence and mortality.
    • The presence of adenomatous polyps (precancerous) allows for precursor lesion removal, preventing cancer.
    • Various screening tests are available, including stool-based tests, endoscopy, and radiologic tests; colonoscopy is often preferred.
    • Hereditary syndromes increase CRC risk; genetic testing can identify these individuals.

    CRC Epidemiology

    • CRC is the third leading cause of cancer incidence and mortality in the US and WEurope, affecting both men and women.
    • Estimated 2020 incidence: 142,820 cases (73,680 in men, 69,140 in women).
    • Estimated 2020 mortality: 50,830 deaths (26,300 in men, 24,530 in women).
    • Worldwide incidence (2008): 1,230,000 cases, 609,000 deaths.
    • Worldwide (2008) European incidence: 450,000 cases, 230,000 deaths.

    CRC Etiology

    • Sporadic CRC etiology is unknown, likely a combination of environmental and genetic factors.
    • Familial adenomatous polyposis (FAP) patients have a high CRC risk due to a mutated APC gene.
    • Lynch syndrome patients inherit a mutated DNA mismatch repair gene, increasing CRC risk.

    CRC Pathology/Pathogenesis

    • Three main molecular pathways are involved:
      • Chromosomal instability (CIN): Accounts for ~70% of colon cancers.
      • Microsatellite instability (MSI): Seen in ~15% of sporadic CRC and all Lynch syndrome CRC.
      • CpG island methylator phenotype (CIMP): Present in at least 15% of CRCs.

    CRC Risk Factors

    • Highest risk: Age over 50, birth in "Westernized" countries, hereditary syndromes (FAP, Lynch), long-standing IBD (ulcerative colitis, Crohn's colitis).
    • Moderate risk: Diet rich in red meat, previous adenoma/CRC, pelvic irradiation, diet rich in animal fat, obesity, smoking, alcohol, cholecystectomy.
    • Protective factors: Colonoscopy/sigmoidoscopy, physical activity, aspirin/NSAID use, diet rich in fiber/fruits/vegetables, calcium/folate supplements, hormone replacement therapy.

    CRC Clinical Diagnosis

    • History should include details about symptoms like changes in bowel habits, blood in stool, abdominal pain, and weight loss.
    • Medical history should consider family history of colon cancer, polyps, and other cancers (especially gynecologic).
    • Patients with suspected FAP should have their extraintestinal manifestations detailed. Ask about red meat, fruits/vegetables, and fiber intake.
    • Be aware that medications (e.g., aspirin, NSAIDs) can cause occult GI bleeding, potentially confounding diagnosis.

    CRC Patient Examination

    • Abdominal mass, signs of anemia, hepatomegaly
    • Digital rectal examination

    CRC Diagnostic Tests

    • Colonoscopy with biopsy (preferred).
    • Sigmoidoscopy with biopsy (if colonoscopy is unavailable).
    • CT scan of abdomen/pelvis (to rule out metastasis).
    • CT colonography (if colonoscopy is unavailable; no tissue diagnosis).
    • MRI of abdomen/pelvis (if CT unavailable or to avoid radiation).
    • Serum CEA (carcinoembryonic antigen) test (useful mainly for follow-up after treatment).
    • CBC, LFTs (to assess for anemia, liver involvement).

    CRC Screening Guidelines

    • Average risk: Screening begins at 45 via stool tests or visual exams.
    • High risk individuals: Screening before 45 and more frequent tests.

    CRC Staging

    • Staging is based on the TNM classification.
      • T (tumor): Primary tumor size and invasion.
      • N (nodes): Regional lymph node involvement.
      • M (metastasis): Distant metastasis presence.

    CRC Treatment

    • Surgery is the cornerstone of treatment for stages I and II.
    • Adjuvant chemotherapy is given for stage III.
    • Advanced disease chemotherapy regimens are used for stage IV.
    • Neoadjuvant therapy (chemo/radiation) followed by postoperative therapy is common for rectal cancers.
    • Polyp removal (polypectomy) might be curative, depending on the characteristics, for certain colorectal tumors.

    CRC Distant Metastasis

    • Common sites: Liver, lung, brain, bone.

    CRC Follow-up

    • Includes history and physical every few months or years.
    • CEA monitoring may be included at intervals.
    • Imaging/endoscopy to assess for recurrent disease, with specific intervals based on risk factors.

    CRC Prevention

    • Limit red meat intake (500 g/week or 70 g/day recommended for healthy adults, with limiting processed meats).
    • Eat high fiber foods (wheat bran, vegetables).
    • Avoid exposure of meat to high heat.

    Colorectal Polyps

    • GI polyp is a discrete tissue mass protruding into the bowel lumen.
    • Classification based on appearance (flat, sessile, pedunculated).
    • Histologic characteristics are crucial for classification.
    • Hyperplastic polyps, hamartomas, inflammatory polyps, and neoplastic polyps (tubular, tubulovillous, villous, serrated) have differing malignant potentials.
    • Advanced adenomas (large size, villous histology, high-grade dysplasia) have a higher cancer risk.
    • Sessile serrated polyps have a cancer development propensity similar to adenomas.

    Colorectal Polyp Detection

    • Polyps are often silent.
    • Detected in asymptomatic screened individuals or incidentally during other investigations (e.g., iron deficiency anemia).
    • Symptoms can include bleeding or obstruction.

    Colorectal Polyp Diagnosis

    • Fecal occult blood tests (FOBT/FIT).
    • Fecal DNA screening tests.
    • Colonography (CT or MRI) cannot detect small polyps accurately.
    • Colonoscopy is effective for screening, diagnoses, and polypectomy .
    • Sigmoidoscopy is useful for screening when combined with FOBT.
    • NICE classification can help with assessing the risk of cancerous lesions.

    Hereditary Colorectal Cancer Syndromes

    • These account for a significant percentage of all large-bowel malignancies (~15%).
    • Several well-defined syndromes are known.
    • Patients with gene mutations may have elevated risks of cancers outside the colon.

    Familial Adenomatous Polyposis (FAP)

    • Genetic mutation in the APC gene causes the development of polyps in the colon.
    • Typically, all polyps in FAP become cancerous.
    • Colon cancer development begins in the teens/20s and progresses to total cases by 40s without treatment.
    • Detection involves genetic testing and regular colonoscopies.
    • Treatment generally involves total proctocolectomy (removal of colon and rectum).
    • Upper endoscopy (EGD) is needed for stomach and duodenum surveillance from age 20 onwards.

    Lynch Syndrome

    • Also known as hereditary nonpolyposis colorectal cancer (HNPCC).
    • Genetic predisposition to diverse cancers, primarily colorectal, due to malfunctioning DNA mismatch repair genes.
    • Bethesda Criteria are used for diagnosis based on patient history and/or genetic testing.

    Bethesda Criteria

    • Criteria for diagnosing Lynch syndrome, based on family history and testing of cancerous tissue (MSI or MMR deficiency).

    Molecular Genetic Evidence (Further Details)

    • Several genetic alterations in oncogenes and tumor suppressor genes (like APC, KRAS, DCC, and p53) drive the development and progression of colon cancer.
    • The progression from polyps to malignant cancer takes ~10-20 years with progression through stages from initiation to metastasis).

    Molecular Genetic Testing (Used in Lynch Syndrome)

    • MLH1, MSH2, MSH6, and PMS2 are important genes involved in Lynch syndrome; certain genetic variations in these genes affect risk.

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    Colorectal Cancer & Polyps PDF

    Description

    This quiz explores key facts about colorectal cancer (CRC), including its prevalence, screening methods, and the importance of early detection. It highlights how screening for at-risk individuals can dramatically decrease incidence and mortality rates. Understand the epidemiology and risk factors associated with this common cancer.

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