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Oncology > Colorectal/anal cancer > Flashcards

Colorectal/anal cancer Flashcards

1
Q

Epidemiology of colorectal cancer

A

2nd most common cancer diagnoses

2nd leading cause of death of cancer in men

3rd leading cause of death of cancer in women

incidence higher in men than women - incidence rates are declining due to screening

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2
Q

Etiology of colorectal cancer

A

Diet low in fibre or calcium high in fat or phosphate

  • a diet high in processed meats and red meats has been associated with a high risk

Obesity

Smoking

Excessive alcohol drinking

Family history

  • having a first degree relative with colorectal cancer

Inflammatory bowel disease

  • Crohn’s disease: 2% developed cancer in 10 years
  • ulcerative colitis: 20% in 10 years

Adenomatous polyps

Hereditary cancer syndromes:

  • familial adenomatous polyposis
  • hereditary nonpolyposis colorectal syndrome or Lynch syndrome
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3
Q

Eight regions of the colon

A
  • cecum
  • ascending colon - immobile, retroperitoneal
  • descending colon - immobile, retroperitoneal
  • splenic flexure - immobile, retroperitoneal
  • hepatic flexure -immobile, retroperitoneal
  • transverse colon
  • sigmoid
  • rectum - continuous with the sigmoid and begins at the level of the third sacral vertebrae
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4
Q

Four main layers of the large bowel

A

Mucosa

Submucosa

Muscularis propria

Serosa

These layers are used in the staging system to define the involvement through the bowel wall.

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5
Q

Mucosa

A

The innermost layer forms the lumen of the bowel wall.

Consists of two supporting layers:

  • lamina propria
  • muscularis mucosa
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6
Q

Submucosa

A

Second most inner layer. Is rich with blood vessels and lymphatics.

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7
Q

Muscularis propria

A

Contains two muscle layers, one circular and one longitudinal which are responsible for peristalsis. Beneath the muscularis layer is a layer of fat termed the subserosal layer.

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8
Q

Serosa

A

The outermost layer. Not all segments of the colon have a serosa layer. This layer is provided by the visceral peritoneum.

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9
Q

Ascending colon lymphatic drainage

A

Follows the superior mesenteric vessels.

  • ileocolic
  • right colic nodes
  • pericolic
  • middle colic
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10
Q

Hepatic (right colic) flexure lymph drainage

A
  • pericolic nodes
  • middle colic nodes
  • right colic nodes
  • ileocolic nodes
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11
Q

Cecum lymphatic drainage

A
  • pericolic
  • anterior cecal
  • posterior cecal
  • ileocolic
  • right colic
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12
Q

Transverse colon lymphatic drainage

A
  • pericolic nodes
  • middle colic nodes
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13
Q

Splenic (left colic) flexure lymph node drainage

A
  • pericolic
  • middle colic
  • left colic
  • inferior mesenteric nodes
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14
Q

Descending colon

A
  • pericolic nodes
  • left colic nodes
  • inferior mesenteric nodes
  • sigmoid nodes
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15
Q

Sigmoid colon lymph drainage

A
  • pericolic
  • perirectal
  • sigmoid mesenteric
  • inferior mesenteric
  • superior rectal
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16
Q

Rectum lymph drainage

A

Upper 1/3 –> superior rectal nodes –> sigmoid mesenteric nodes –> inferior mesenteric nodes

Middle and lower 1/3 –> middle and infererior rectal nodes –> internal iliac nodes

Other nodes: obturator, lateral sacral, presacal, sacral promontory nodes.

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17
Q

Clinical presentation of colorectal cancer

A

Abdominal pain

Change in bowel habits

  • pencil-thin stool, constipation or diarrhea may indicate obstructive tumour
  • more common with left-sided colon cancer

GI bleeding

  • more common with right-sided colon cancer

Isolated anemia

Weightloss

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18
Q

Colorectal cancer screening

A

A person of average risk beginning at 50 should undergo a fecal immunochemical test, flexible sigmoidoscopy, double-contrast barium enema, or CT every 5 years. A colonoscopy should follow up any positive results.

A person with genetic factors should undergo colonoscopies before the age of 50

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19
Q

Colonoscopy

A

Should be done every 10 years. Examines the entire colon and can visualize polyps and allow them to be removed for examination.

High sensitivity for detecting mucosal regions.

A newer technique called 3D-colonoscopy uses a CT scanner and 3D software which examine the inside of the colon without the lengthy scope. Has the same radiation exposure as a barium enema.

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20
Q

Flexible sigmoidoscopy

A

Evaluation of splenic flexure only.

Up to 66% of tumours can be missed due to incomplete bowel evaluation.

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21
Q

Capsule endoscopy

A

Ingested capsule provides a photographic evaluation of colon and rectum

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22
Q

Double-contrast barium enema

A

Useful in patients with incomplete colonoscopy

Requires additional procedure for the intervention of biopsy.

Detects only 20% of polyps found on colonoscopy

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23
Q

Proctosigmoidscopy

A

Is performed after detection with colonoscopy can provide a more accurate depiction of the size and location of the lesion.

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24
Q

Pathology of colorectal carcinoma

A

Adenocarcinoma accounts for 90-95% of all cancer.

Other histologic types include:

  • mucinous adenocarcinoma
  • signet-ring cell carcinoma
  • squamous cell carcinoma
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25
Q

Tis colorectal cancer

A

Intraepithelial or invasion of lamina propria

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26
Q

T1 colorectal cancer

A

Tumour invades submucosa

27
Q

T2 colorectal cancer

A

Tumour invades muscular propria

28
Q

T3 colorectal cancer

A

Tumour invades through muscularis propria into the peri-colorectal tissues

29
Q

T4 colorectal cancer

A

T4a: penetrates to the surface of the visceral peritoneum

T4b: tumour directly invades or is adherent to other organs or structures.

30
Q

N1 colorectal cancer

A

Metastasis to 1 to 3 regional lymph nodes

N1a: metastasis to 1 regional lymph nodes

N1b: metastasis to 2 or 3 regional lymph nodes

N1c: Tumour deposits into the subserosa, mesentery or nonperitonealized pericolic or perirectal tissues without regional node metastasis

31
Q

N2 colorectal cancer

A

Metastasis into 4 or more regional lymph nodes

N2a: metastasis in 4 or 6 regional nodes

N2b: metastasis in 7 or more regional nodes

32
Q

M1 colorectal cancer

A

M1a: metastasis confined to one organ or site

M1b: metastasis in more than one organ or the site or in the peritoneum

33
Q

Routes of spread for colorectal cancer

A

Local spread: penetration of bowel wall and invasion of adjacent organs

Perineural invasion: local spread may be as far as 10cm from the primary tumour

Lymphatics

Liver and lungs are most common sites of hematogenous metastasis

34
Q

Surgery of colorectal cancer

A

Surgery is considered the treatment of choice. The tumour and adequate margin and lymphatics are removed.

The two most common rectal surgeries are:

  • lower anterior resection
  • abdominoperineal resection
35
Q

Low anterior resection (LAR)

A

Removal of tumour plus margins as well as regional lymphatics. The bowel is anastomosed therefore a colostomy is not necessary. Used to treat colon cancer and some rectal cancers.

36
Q

Abdominoperineal resection (APR)

A

Used for patients with rectal cancers in the lower distal third of the rectum.

An anterior incision is made into the abdominal wall to make a colostomy.

Then a perineal incision is made to resect to rectum, anus and drainage lymphatics with the entire enbloc removed through the incision.

Finally, the reperitonilization is done for patients who have post-operative radiotherapy to pull the small bowel more superior and reduce toxicity after RT.

37
Q

Radiation therapy for colorectal cancer

A

Most commonly used adjuvant treatment for colorectal cancer. Can be done before or after surgery or in conjunction with chemotherapy.

38
Q

Post-operative RT colorectal cancer

A

Concurrent chemotherapy is advocated based on the high local failure rate of surgery alone with patients who have nodal involvement or tumour extension beyond the rectal wall.

Post-op RT with chemotherapy has been shown to improve local control and survival rates in patients with rectal cancer.

The advantage to post-op RT is the oncologist has the pathological information of the tumour and the extent of spread as well as nodal information.

39
Q

Pre-operative RT for colorectal cancer

A

Common for patients who have large rectal cancers that have invaded through the muscle layer (T3) or have enlarged lymph nodes (N1 or N2).

The goal of this is sphincter preservation. This is done to shrink the tumour and then a LAR can be done instead of APR, therefore reducing the need for colostomy.

A disadvantage is there is no pathology information on the tumour before beginning RT.

40
Q

Common TDF’s colorectal cancers

A

Dose to large volume: primary + LN’s is 4500cGy

Dose to primary tumour bed: 5000 to 5500cGy in 6 to 6.5 weeks.

Doses of over 5000cGy are not achievable unless the small bowel is out of the treatment field.

41
Q

Treatment volume colorectal cancer

A

Sup: L5-S1 (with more advanced disease may go up to L4)

Inf: includes the entire obturator foramina. (or 3-5cm below gross tumour before resection)

Lateral: 2cm lateral to the pelvic brim

Ant: behind the pubic symphysis

Post: 2cm behind sacrum to include pre-sacral LN’s

42
Q

Prognostic factors of colorectal cancer

A

Patients who had pre-op RT do better

Lymphatics and venous invasion are adverse factors

Patients with tumours around the peritoneal reflections either rectosigmoid or rectum have a worse 5-year survival

5-year survival:

symptomatic patients: 49%

Asymptomatic patients: 71%

43
Q

Epidemiology of anal cancer

A

More common in women than men.

General age distribution in 30-90 years with a median age of 60.

Men younger than 45 have seen a rise in rates of anal cancer most likely contributed to anal sex and HPV.

44
Q

Etiology of anal cancer

A

Genital warts

Genital infections

HPV

Anal intercourse in men or women before the age of 30

Smoking has also seen to increase the chance of anal cancer

45
Q

Anatomy of anal canal

A

3-4cm long extends from the anal verge to the anorectal ring at the junction of the anus and the rectum.

46
Q

Lymphatics of the anal canal

A

Initially to the perirectal and anorectal lymph nodes.

If the tumour extends above the dentate lime the lymph nodes at risk are:

  • internal iliac nodes
  • lateral sacral nodes

If the tumour extends below the dentate lime the lymph nodes at risk are:

  • inguinal nodes
47
Q

Dentate line

A

Divides the upper 2/3 of the anal canal from the lower 1/3 of the anal canal

48
Q

Clinical presentation of anal cancer

A

The most common presenting symptom is rectal bleeding (bright red).

Other symptoms may include pain, bowel changes and the sensation of a mass.

49
Q

Detection and diagnoses of anal cancer

A

Digital anorectal exam and palpation of inguinal nodes

Anoscopy or proctoscopic examination and biopsy should also be obtained.

50
Q

Pathology of anal cancer

A

Squamous cell carcinoma is the most common histology of anal cancer.

Basaloid (cloacogenic) cancers are the next most frequent pathology occurs around the dentate line where the epithelium changes.

Adenocarcinoma may be diagnosed in the anal glands.

51
Q

T1 stage anal cancer

A

Tumour 2cm or less in greatest dimension

52
Q

T2 stage anal cancer

A

Tumour more then 2cm but less then 5 in greatest dimension

53
Q

T3 stage anal cancer

A

Tumour greater then 5cm in greatest dimension

54
Q

T4 stage anal cancer

A

Tumour of any size invades adjacent organs (vagina, urethra, bladder).

55
Q

N1 stage lymph nodes

A

Metastasis in perirectal lymph nodes

56
Q

N2 stage anal cancer

A

Metastasis in unilateral internal iliac or inguinal lymph nodes

57
Q

N3 stage anal cancer

A

Metastasis in perirectal and inguinal nodes or bilateral internal iliac or inguinal nodes

58
Q

Routes of spread for anal cancer

A

Most frequently via direct extension into adjacent soft tissues.

Lymphatic spread occurs relatively early to pelvic nodes but more commonly to inguinal nodes.

Hematogenous spread to liver and lung is less common

59
Q

Chemotherapy associated with anal cancer

A

5-FU and mitomycin C is the most common treatment along with radiation

Cisplatin is also used with 5-FU and typically has less side effects.

60
Q

A most common treatment for anal cancer

A

Chemoradiation is the preferred treatment this has been shown to provide good local control and colostomy-free survival.

Radiation alone is an option for those who can not handle chemoradiation.

61
Q

Most common surgical procedure for anal cancer

A

Abdominoperineal resection with a wide perineal dissection is the most common. Although no longer the initial treatment of anal cancer. Done if local recurrence after chemoradiation.

62
Q

Field borders anal cancer

A

Sup: L5-S1

Inf: 3cm below the anal marker

Lat: 1.5-2cm from the pelvic brim

63
Q

TDF for anal cancer

A

RT alone: 6000 to 6500cGy to pelvis with a field reduction and 4500cGy primary tumour to reduce small bowel toxicity.

Combined modality: 4500cGy with a smaller field boost of 1440cGy to 2440cGy to primary tumour

64
Q

Most common side effects of RT for anal cancer

A

Perineal skin reaction, nausea, vomiting and diarrhea are most reported.

Oncology (11 decks)

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