COLORECTAL CANCER Flashcards
epidemiology of colorectal cancer
Most common GI cancer Best prognosis of all GI cancers M=F Risk factor: age 2nd leading cause of cancer deaths in Canada 50% rectum 20% sigmoid 16% cecum and ascending colon 8% transverse colon and splenic flexure 6% descending colon
etiology of colorectal cancer
Diet high in animal fat, diet low in fibers
Chronic ulcerative colitis
FAP, familial adenomatous polyposis
Genetic factor, 1st degree relative
anatomy around colorectal cancer
Small intestine
Duodenum
Jejunum
Ileum
Large intestine
Cecum
Colon
Rectum
Colon Ascending colon Transverse colon Descending colon Sigmoid colon
Mesentery, point of attachment to abdominal cavity
natural history of colorectal cancer
.
clinical presentation of colorectal cancer
Hematochezia (rectal bleeding) Bright red blood in stools Change in bowel Diarrhea Constipation Pencil-thin stool Tenesmus (rectal spasms and feeling to empty bowel)
50% of patients present with positive node involvement at diagnosis
pathology of colorectal cancer
Adenocarcinoma 90-95% Other: Mucinous adenocarcinoma Signet ring cell carcinoma Squamous cell carcinoma
staging system for colorectal cancer
Dukes staging classification
route of spread of colorectal cancer
Direct extension to adjacent structures Lymph node spread via intraperitoneal or retroperitoneal nodes Hematogenously Peritoneal seeding spread Distant METS to Liver Lung
rationale of SURGERY when treating colorectal cancer
Surgery is the treatment of choice for most colorectal cases
Type of surgery
Low anterior resection (LAR) needs no colostomy, bowel is reanastamosed, used for upper and middle rectum, for sphincter preservation
Abdominoperineal resection (APR) needs colostomy and used for lower third of rectum
rationale of CHEMOTHERAPY when treating colorectal cancer
Chemotherapy is used as a radiosensitizer as used with Post-op Rt to improve survival rates with positive nodes
rationale of RADIATION THERAPY when treating colorectal cancer
Radiation therapy is commonly used Post-operative with chemotherapy
Plan 1 45 Gy/ 25 fx
Plan 2 5.4-14.4 Gy / 3-8 fx
Brachytherapy 26 Gy / 4 fx HDR Ir-192 Intracavitary ONCENTRA planning system
rationale of using combined modalities when treating colorectal cancer
Surgery + Chemotherapy + post-op Radiation Therapy
?
5 year survival rates for colorectal cancer
.
RT treatment technique used to treat colorectal
.
RT side effects when treating colorectal cancer
Acute effects Diarrhea, due to small bowel irradiation Abdominal cramps Bloating Proctitis (rectum inflammation) Dysuria Erythema Dry desquamation Wet desquamation Leukopenia due to chemo, need weekly CBC Thrombocytopenia due to chemo, need weekly CBC
Chronic effects Persistent diarrhea Bowel frequency Proctitis Urinary incontinence Bladder toxicity Enteritis (inflammation small bowel) Obstruction
