POLYPS 4

lmay remain asymptomatic for years

lsymptoms develop insidiously

lcecal and right colonic cancers:

lfatigue

lweakness

liron deficiency anemia

lleft-sided lesions:

loccult bleeding

lchanges in bowel habit

lcrampy left lower quadrant discomfort

lanemia in females may arise from gynecologic causes, but it is a clinical maxim that iron deficiency anemia in an older man means gastrointestinal cancer until proved otherwise

lspread by direct extension into adjacent structures and by metastasis through lymphatics and blood vessels

lfavored sites for metastasis:

lregional lymph nodes

lliver

llungs

lbones

lother sites including serosal membrane of the peritoneal cavity

lcarcinomas of the anal region → locally invasive, metastasize to regional lymph nodes and distant sites

TNM Staging of Colon Cancer

Tumor (T)

T0 = none evident

Tis = in situ (limited to mucosa)

T1 = invasion of lamina propria or submucosa

T2 = invasion of muscularis propria

T3 = invasion through muscularis propria into subserosa or nonperitonealized perimuscular tissue

T4 = invasion of other organs or structures

Lymph Nodes (N)

0 = none evident

1 = 1 to 3 positive pericolic nodes

2 = 4 or more positive pericolic nodes

3 = any positive node along a named blood vessel

Distant Metastases (M)

0 = none evident

1 = any distant metastasis

5-Year Survival Rates

T1 = 97%

T2 = 90%

T3 = 78%

T4 = 63%

Any T; N1; M0 = 66%

Any T; N2; M0 = 37%

Any T; N3; M0 = data not available

Any M1 = 4%

lStage 0-

lIn Stage 0, the cancer is at a very early stage and is located only in the inner lining of the colon. The recommended treatment for Stage 0 colon cancer is surgical removal of the tumor, along with parts of the colon on either side of the tumor site. If detected early, colon cancer is highly curable and has a low risk for recurrence.

lStage 1-

lin this stage, the cancer has grown through several layers of the colon, but is still confined to the wall of the colon. It has not spread to nearby organs as yet. Surgery is the recommended treatment at Stage I. Stage I is also highly curable, with a low risk for recurrence.

lStage 2-

lIn Stage II, the cancer has spread (metastases) to nearby organs or tissues, but not to the lymph nodes. Lymph nodes are small, bean-shaped structures where cells are stored; nodes can trap cancer cells or bacteria traveling through the body. The recommended treatment for Stage II is surgical removal of the tumor. Adjuvant therapy (chemotherapy and radiation therapy) is also suggested for Stage II patients with recurrences.

lStage 3-

In this stage, the cancer has spread outside the large intestine to regional lymph nodes, but not to other body parts. Treatment for Stage III colon cancer includes surgical removal of a section of the colon and rejoining the remaining ends (anastomosis). Surgery is usually followed by chemotherapy. Studies have shown that the number of lymph nodes involved affects the outcome. Patients with 1-3 nodes involved have significantly greater survival rates than those with 4 or more nodes involved.

lStage 4-

Stage IV is the most advanced stage of colon cancer. The cancer has spread beyond the colon, rectum or regional lymph nodes to distant organs or tissue (such as liver, ovaries and lungs). Although cancer is not usually curable at this stage, surgery is still the recommended treatment. Surgical resection of the colon and reconnection of the large intestine is done so as to blockage of the colon and any other local complications. Chemotherapy and/or radiation are generally given for palliative purposes.

ldetection and diagnosis:

ldigital rectal examination

lfecal testing for occult blood loss

lbarium enema, sigmoidoscopy and colonoscopy

lconfirmatory biopsy

lcomputed tomography and other radiographic studies

lserum markers (elevated blood levels of carcinoembryonic antigen)

lmolecular detection of APC mutations in epithelial cells, isolated from stools

ltests under development: detection of abnormal patterns of methylation in DNA isolated from stool cells

lchemotherapy

lradiotherapy

lphotodynamic therapy

lradical surgery

lgene therapy

lColon cancer can be prevented and cured through early detection

lChanging your eating habits( more fiber and less fats)

lDon’t smoke and drink less

lYou may have heard that taking aspirin prevents colon cancer. This is an exciting area of research, and studies are currently underway to evaluate whether aspirin can prevent the recurrence of precancerous colon polyps.

QUESTIONS

 98% of all cancers in the large intestine are adenocarcinomas.

Use of Aspirin® and other NSAIDs may cause development of colon cancer.

Chromosome instability and the mismatch repair are two carcinogenesis pathways.

Tumors in the proximal colon tend to be annular, encircling lesions that produce “napkin-ring” constrictions of the bowel and narrowing of the lumen, while those in the distal colon tend to grow as polypoid, exophytic masses.

Colorectal carcinoma may remain asymptomatic for years.

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