Left colon cancer pt.1

Question 1

Where does colon cancer rank globally in cancer frequency

Answer 1

Colorectal cancer is third globally in cancer incidence and cancer death

Question 2

In which portions of the colorectum does cancer arise?

Answer 2

• About 70 % in colon (About 25% in right and 35% in left)
• By portion: Cecum 14 %, Ascending colon 10 %, Transverse colon 12 %, Descending colon 7 %, Sigmoid colon 25 %, Rectum 23 %

Question 3

Age and incidence of colorectal cancer

Answer 3

Large bowel cancer is uncommon before the age of 40; the incidence begins to increase significantly between the ages of 40 and 50, and age-specific incidence rates increase in each succeeding decade thereafter

Question 4

Sporadic vs familial cases of colon cancer

Answer 4

Majority of CRCs are sporadic rather than familial

Question 5

Risk factors for developing colon cancer

Answer 5

• Environmental and genetic factors can increase the likelihood of developing CRC
• Factors can be divided into ones that influence screening recommendations and ones that don’t

Question 6

What are factors that currently influence screening recommendations for colorectal cancer?

Answer 6

CRC screening recommendations are modified for members of families with hereditary colon cancer syndromes, on the basis of personal or family history of CRC or adenomas (Up to 25% of patients with colorectal cancer have a family history of
the disease), in patients with inflammatory bowel disease, and in those who have been exposed to abdominal radiation therapy

Question 7

Which familial syndromes are associated with a high risk of developing colorectal cancer? How much do they contribute to the total number of colorectal cancer?

Answer 7

• Familial adenomatous polyposis (FAP, aka polyposis coli) and Lynch syndrome (hereditary nonpolyposis colorectal cancer [HNPCC]) are the most common of the familial colon cancer syndromes, but together these two conditions account for only approximately 5 percent of CRC cases, the majority of which are Lynch syndrome
• MYH-associated polyposis (MAP) can also lead to it but is rare

Question 8

Which IBDs are associated with an increased risk of colorectal cancer?

Answer 8

• Ulcerative colitis (more so than CD)
• Chron’s disease

Question 9

Screening age recommendation for colorectal cancer

Answer 9

• ACG (American college of Gastroenterology) and US Preventive Services Task Force (USPSTF) recommended that average-risk patients over the age of 45 years be screened for CRC
• Initiating screening at age 50 years for average-risk adults is recommended by the Canadian Task Force on Preventive Health Care (CTFPHC), the European Council, the American Academy of Family Physicians (AAFP), and the American College of Physicians (ACP)

Question 10

Sex and colorectal cancer

Answer 10

• Rates of both incidence and mortality are substantially higher in males than in females
• CRC mortality is approximately 33 percent higher in males than in females

Question 11

Protective factors for colon cancer

Answer 11

These include regular physical activity, a variety of dietary factors (diet high in fruits and vegetables, resistant starch, Vitamin D, antioxidants), and the regular use of aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs)

Question 12

Impact of race on CRC

Answer 12

• Black Americans, Native Americans, and Alaskan Native individuals have among the highest incidence and mortality rates for CRC of all racial and ethnic groups in the United States
• In addition, CRCs occur at a younger age, as there is a higher frequency of CRC under age 50 in these populations

Question 13

What are factors that currently don’t influence screening recommendations for colorectal cancer?

Answer 13

• There are a large number of clinical, environmental, and lifestyle factors that are associated with a small and/or uncertain increased risk of CRC
• Although many of these associations have been seen consistently in observational studies, the causal relationship of these associations is largely unproven
• Patients may be counseled about these associations and encouraged to reduce or avoid such factors for the primary prevention of CRC.
• These include obesity, diabetes, processed meats (red meat might have an impact but less than processed meats), alcohol use, smoking, Cholecystectomy, Streptococcus bovis bacteremia, acromegaly, use of androgen deprivation therapy

Question 14

How do patients with CRC present to the clinic?

Answer 14

Patients with CRC may present in three ways:
●Suspicious symptoms and/or signs
●Asymptomatic individuals discovered by routine screening
●Emergency admission with intestinal obstruction, perforation, or rarely, an acute gastrointestinal bleed

Question 15

What are the symptoms of CRC?

Answer 15

• There are no symptoms in the majority of patients with early-stage colon cancer and these patients are diagnosed as a result of screening
• Symptoms of CRC are typically due to growth of the tumor into the lumen or adjacent structures, and as a result, symptomatic presentation usually reflects relatively advanced CRC
• Typical symptoms/signs associated with CRC include hematochezia (more often caused by rectosigmoid than right-sided colon cancer) or melena, abdominal pain, otherwise unexplained iron deficiency anemia (more often right-sided CRC), and/or a change in bowel habit (more often in left than right CRC) (e.g. constipation)
• Unspecific symptoms such as weight loss and weakness

Question 16

Stats about when CRC is usually diagnosed?

Answer 16

• Most CRCs (70 to 90 percent in two contemporary series) are diagnosed after the onset of symptoms
• Up to 20% of patients have distant metastatic disease at the time of
  presentation

Question 17

Symptoms of left colon cancer

Answer 17

• Constipation
• Alternating bowel patterns
• Abdominal pain,
• Narrowed stool caliber
• Tenesmus
• Rectal bleeding
• Bright Red Blood per Rectum
• Large Bowel Obstruction

Question 18

Symptoms of right colon cancer

Answer 18

• Lesions of the right colon commonly ulcerate, leading to chronic, insidious blood loss without a change in the appearance of the stool
• Consequently, patients with tumors of the ascending colon often present with symptoms such as fatigue, palpitations, and even angina pectoris and are found to have a hypochromic, microcytic anemia, indicative of iron
  deficiency
• Weight loss
• Rarely obstruction

Question 19

Symptoms of rectal cancer

Answer 19

Obstruction, tenesmus, bleedingPalpable mass on rectal exam, bright Red Blood Per Rectum

Question 20

What is hematochezia?

Answer 20

The passage of fresh blood per anus, usually in or with stools

Question 21

What is tenesmus?

Answer 21

A repeated, painful urge to defecate without excreting stool

Question 22

Origin of CRC

Answer 22

Most colorectal cancers (CRCs) originate from adenomatous polyps or flat dysplasia

Question 23

Morphology of CRCs

Answer 23

• Gross appearances depend on location
• Tumors in the proximal or right colon usually appear grossly as polypoid (resembling or in the form of a polyp) or fungating (looking like a fungus) exophytic (arising from the outer surface of the organ of origin) masses
• Tumors involving the distal or left colon are more commonly annular (ring-shaped) or encircling lesions that produce an “apple-core” or “napkin-ring” appearance
• Right- and left-sided colon cancers are microscopically similar

Question 24

Type of carcinoma found in CRC

Answer 24

• Of the carcinomas, more than 90 percent are adenocarcinomas
• Other histologic types of tumors (neuroendocrine neoplasms, hamartomas, mesenchymal tumors, lymphomas) are relatively unusual

Question 25

What are some mutations associated with colorectal cancer development?

Answer 25

• APC, K-ras, P53
• COX2 overexpression is associated with furthering development

Question 26

How many polyps become carcinomas in the colorectum?

Answer 26

• Less than 1%
• The likelihood that any polypoid lesion in the large bowel contains invasive cancer is related to the size of the polyp, being negligible (<2%) in lesions <1.5 cm, intermediate (2–10%) in lesions 1.5–2.5 cm, and substantial (10%) in lesions >2.5 cm in size

Question 27

What is a polyp?

Answer 27

A grossly visible protrusion from the mucosal surface

Question 28

What can polyps be classified into?

Answer 28

• May be classified pathologically as a nonneoplastic hamartoma (e.g., juvenile polyp), a hyperplastic mucosal proliferation (hyperplastic polyp), or an adenomatous polyp
• Polyps may be pedunculated (stalked) or sessile (flat-based), adenomatous or serrated (notched like the cutting edge of a saw)
• Histologically, adenomatous polyps may be tubular, villous (i.e., papillary), or tubulovillous

Question 29

Which types of polyps are more likely to cause malignancy?

Answer 29

• Only adenomas are clearly premalignant
• Invasive cancers develop more
  frequently in sessile, serrated (i.e., “flat”) polyps
• Villous adenomas, most of which are sessile, become malignant more than three times as often as tubular adenomas

Question 30

How many polyps are expected to be found in a person?

Answer 30

• Adenomatous polyps may be found in the colons of ~30% of middle-aged and ~50% of elderly people
• Such patients have a 30–50% probability of developing another adenoma and are at a higher-than-average risk for developing a colorectal carcinoma
• Following the detection of an adenomatous polyp, the entire large bowel should be visualized endoscopically because synchronous lesions are noted in about one-third of cases

Question 31

T description for colorectal cancer

Answer 31

• T1 no deeper than submucosa
• T2 Invades muscularis propria
• T3 Penetrates through muscularis and invades subserosa (involving serosa and/or mesorectal or pericolic fat)
• T4 Invades peritoneal reflection (visceral peritoneum) (T4a) or other organs (T4b)

Question 32

N description for colorectal cancer

Answer 32

• N1 invades 1-3 perirectal or pericolic lymph nodes
• N2 invades 4+ pericolic or perirectal lymph nodes

Question 33

M description for colorectal cancer

Answer 33

M1 distant metastasis

Question 34

Clinical staging based on TNM

Answer 34

T1-T2 N0 M0 stage 1
T3-4 N0 M0 stage 2
Any T Any N1-N2 M0 stage 3
Any T Any N M1 is stage 4

Question 35

How many lymph nodes should be sampled for staging of colorectal cancer

Answer 35

A minimum of 12 sampled lymph nodes is thought necessary to accurately define tumor stage, and the more nodes examined, the better.