Colorectal Cancer Flashcards
What is colorectal cancer?
Term used for cancer that starts in the colon or rectum. These cancers can also be referred to separately as colon cancer or rectal cancer, depending on where they start. Colon cancer and rectal cancer have many features in common.
Etiology of Colorectal cancer
- 3rd most commonly diagnosed cancer in the US
- Over 102k new cases of colon cancer diagnosed in the US in 2013, in addition to more than 40,000 new cases of rectal cancer
- 1 in 20 people will develop in their lifetime, men>women
- incidence is declining
- most common over age 50, incidence rises with increasing age
- Early diagnosis has 90% 5 year survival rate however early diagnosis is rare
Pathophysiology
- Nearly all start as polyps
- Most tumors develop on sigmoid colon or rectum
- spreads by direct extension of the entire bowel circumference, submucosa, and outer bowel walls, neighboring structure also may be involved
Polyps
- small vascular growths on the mucous membrane (in the glandular tissue of intestinal lining)
- Size of polyps correlates with development ( than 1% chance)
Types of Polyps
-Hyperplastic, generally harmless, small,
Polypsosis Syndromes
hereditary conditions which cause polyps. Usually rare, occur in young people.
**high chance of becoming cancerous
Risk Factors for Colorectal Cancer
- Personal or family hx of colorectal cancer and/or polypsosis disorders, inflammatory bowel disease
- Hereditary nonpolyposis (Lynch syndrome) - autosomal dominant disorder - increases occurrence of all cancers
- over 50 yo
- Smoking
- Obesity
- Alcohol
- Radiation exposure
- Diets high in calories, fats, and meat proteins
- Presence of anaerobic but bacteria
Prevention of Colorectal Cancer
- Early detection is key (SCREENING)
- Look for signs/symptoms generally
- For individuals over 50: yearly fecal occult blood test, stool DNA test, Flexible sigmoidoscopy every 5 years, double contrast barium enema every 5 years, colonoscopy every 10 years, CT colonography every 5 years
MAY reduce incidence: exercise, MVI, ASA, NSAIDs
Clinical Manifestations of Colorectal Cancer
- Typically few if any until progression (5-15 yrs in some cases due to slow growth)
- Rectal bleeding-often initial manifestation to seek care
- Changes in bowel habits
- Pain
- Anorexia/weight loss
- Abdominal mass
- Fatigue
- Anemia
Diagnosis
- Endoscopy
- Full colonoscopy better than sigmoidoscopy. Can detect 50-65%
- Tissue for biopsy
- Fecal blood tests
- CBC
- Carcinoembryonic Antigen (CEA)
Carcinoembryonic Antigen (CEA)
- used to monitor course of treatment, prognosis, etc. as well
- others to detect possible areas of metastasis
TNM Staging System for Colorectal Cancer
T: how far primary tumor has grown into the intestinal wall & whether it has grown into nearby areas
N: the extent to nearby (regional) lymph nodes
M: whether the cancer has spread (metastasized) to other organs of the body (most common in colorectal cancer-liver and lungs)
**Numbers or letters appear T, N, & M to provide more details. 0 through 4 indicate increasing severity
Medical Treatments for Colorectal Cancer
- Surgical resection with anastomosis of tumor
- Excision of tumor
- Laser photocoagulation
- Abdominal resection with permanent colostomy
- Fulguration
- Chemo & EBR post-op
- Brachytherapy
Surgical resection with anastomosis of tumor
Treatment of Choice
-adjacent colon and regional lymph node
Excision of tumor
sometimes done during endoscopy
Laser photocoagulation
beam of light to generate heat, destroys small tumors, palliative-obstructions
Abdominal resection with permanent colostomy
attempt to preserve anal sphincter and avoid colostomy
Fulguration
uses electrical current to kill cancer tissue similar to cauterization
Fluoroutacil (5-FU) / Folonic Acid (Leucovorin)
- combined with radiation therapy
- reduces rate of tumor recurrence & prolongs survival for stage 2 and stage 3
- used for both to reduce spread and recurrence
- Antimetabolite, used to disrupt DNA replication
- Given IV (usually) or sometimes topically
- Neutropenia, thrombocytopenia peak 1-2 weeks after treatment
Fluoroutacil (5-FU) / Folonic Acid (Leucovorin) Side Effects
- N/V/D
- alopecia
- Photosensitivity
- cardiotoxicity
- CNS damage (short term, long term)
Bowel Resection
- Surgery (high cure rate for early stage tumors)
- AKA Colectomy
- Remove all or part of large intestines
- Often leads to creation of a colostomy (can be permanent or temporary depending on factors)
- May be open or larascopic
Colostomy
- diversion of fecal contents
- temporary or permanent
- name based on colon affected
Sigmoid Colostomy
MOST COMMON
- permanent
- cancer of the rectum
Doube-barrel colostomy
- two separate stomas are created
- Distal stoma: colon is bypassed, expels mucus
- Proximal stoma: functional, diverts feces to abdominal wall
