Lower GI part 1 Flashcards
What does the Lower GI consist of?
small bowel
colon
rectum
anus
What are the 4 layers of the GI tract from inner to outer?
mucosa (epithelial)
Submucosa (connective tissue- contains blood and lymphatic vessels)
Muscularis (smooth muscle- involuntary contractions to break down food)
Serosa (serous membrane covering GI tract suspended in abdominal cavity
What is the epidemiology & aetiology of the small bowel?
accounts for <5% of gastro-intestinal tumours Malignant lesions occur frequently (duodenum & jejunum) Benign lesions (adenoma & fibromas in ileum)
What are the genetic/ hereditary predispositions for small bowel tumours
polyposis
Crohn’s disease
Gardner’s syndrome
What are the signs & symptoms for Small Bowel cancer?
often silent for long time abdominal pain/cramps chronic anaemia abdominal haemorrhage abdominal mass weight loss diarrhoea
How can cancers of the small bowel spread?
neighbouring organs
regional lymph nodes
What is the pathology of small bowel cancer?
Adenocarcinomas (45%)
Carcinoid (30%)
Lymphomas (10%)
Sarcomas (mostly leiomyosarcoma)
What is the clinical management of small bowel cancer?
primarily resection
post-op RT to tumour bed/ nodal areas
RT and Chemo
Whole abdo RT for lymphomas
If the cancer of the small bowel is unresectable what treatment is used?
Chemo/RT or Pre-op RT
How responsive to radiation are small bowel cancesr?
Generally poor radiosensitivity (except sarcomas)
20-25Gy +/- radiosensitings chemo (5FU or cisplatin based chemo)
What are the general features of the Colon?
1.5m long
ileum to the anus
absorb water
transmit the waste material
What is the epidemiology & aetiology for colorectal cancers?
2nd most commonly diagnosed cancer in Australia
Age
Diet
Alcohol, smoking, obesity, low physical activity
What are the Genetic/ Hereditary predispositions associated with colorectal cancer?
Polyposis
Crohn’s Disease (inflammation of lining of GI tract)
Diverticulitis (pouches along colon become inflamed)
What is the age bracket for colon/rectum cancers?
majority occur in the over 50s
Peak incidence 60 -80 years
What dietary factors affect colorectal cancer (Aetiology)?
high meat, fat, calorie, alcohol intake
What are the signs & symptoms of colorectal cancer?
palpable mass rectal bleeding &/or blood in stool diarrhoea change in bowel habit Tenesmus (cramping rectal pain) Obstructive symptoms Iron deficiency anaemia Weight loss vomiting
How can colorectal cancer be detected?
Faecal occult blood test
Digital Rectal Exam (DRE)
Sigmoidoscopy/ colonscopy
How does colorectal cancer spread?
mucosal walls lymph & blood (submucosal layer) Peritoneal Seeding Pelvic lymph nodes Distant metastases
What are the common sites of distant metastasis for colorectal cancer?
Liver via blood Lung via IVC embolism Bone Ovaries Adrenal
What are the different types of colorectal cancers?
adenocarcinoma
Signet-ring Carcinoma
Squamous Cell Carcinoma
What staging is used for colorectal cancer?
Dukes
Aster-Coller
TNM
What is Dukes Staging for colorectal cancer?
A= no bowel penetration B = bowel penetration C= positive nodes D= metastasis
What is stage A of Dukes Staging for colorectal cancer?
A- Confined to bowel wall ie. musoca and submucosa or early muscular invasion
What is stage C of Dukes Staging for colorectal cancer?
C1- lymph node involvement but not up to highest point of vascular ligation
C2- Nodes involved up to highest nodes at the point of vascular ligation
What is the TNM staging for colorectal cancer?
T1,2,3,4, T1 = submucosa T2= muscularis propria T3 = beyond 2 T4= other organs invaded N1,2 N1= 1-3 nodes N2= >3 nodes M1= metastatic
What are the clinical management options for colorectal cancer?
surgery
radiotherapy
chemotherapy
What are the factors to consider with RT for colon cancer?
Difficult to determine the volume to be irradiated
proximity to OAR
Surgery - colorectal cancer
primary definitive treatment
Total mesorectal excision (TME) (reduced local recurrence rate to <10% compared to 30% previously
What do the inferior mesenteric nodes drain?
Descending Colon
Left side of mesentery
Sigmoid Colon
Rectum
What is the 5yr survival for the Grading for colorectal cancer?
G1-2 = 55% 5 yr survival G3-4 = 30% 5 yr survival
What is a Total Meso-rectal Excision (TME)
Remove the mesenteric fat and muscle around the rectum
How does distance from the ano-rectal junction affect TME?
If the rectal cancer is >5-6cm above the ano-rectal junction then can perform a low anterior resection and join the bowel together (anastomosis)
If less than this then abdomino-perineal resection and permanent colostomy with closure of anus
What is the difference between short and long course of pre-op RT?
short course: doesn’t allow for tumour downstaging) but doesn’t delay surgery for as long, less side effects because tumour cut out 1 week after RT therefore before they experience these side effects
Long course: 28 fractions, more side effects, RT affects healing of cells after surgery
What is the standard dose fractionation for short course (Swedish protocol) pre-op RT? (for rectum)
25Gy in 5 fractions over 1 week, surgery follows in next 7-10 days
improvement 5 year survival
What is the standard fractionation for long course Pre-op RT for rectum
45-50.4Gy in 25-28 fractions over 5-6 weeks
surgery follows approx 8-10 weeks later
(downsizes tumour)
What is the lymphatic drainage of the Anus?
lymph from anal canal drains into superficial inguinal lymph nodes -> external iliac
What is the epidemiology & aetiology of anus cancer?
rare- 2% large bowel cancer slightly more common in women AIDS related HPV SCC (squamous cells)
What is the epidemiology & aetiology of anus cancer?
rare- 2% large bowel cancer slightly more common in women AIDS related HPV SCC (squamous cells)
What are the signs and symptoms of anal cancer?
visible or palpable mass
bleeding
pain &/or discharge
Pruritus (itchiness) (more perianal)
How does anal cancer spread?
local invasion of anal sphincter and rectal wall
Prostate, bladder or cervix spread
What is the staging used for anal cancer?
AJCC (American joint cancer committee) (TNM)
T size
N nodes
M metastatic
What is the Clinical Management of Anal cancer?
RT (only if chemo not tolerated) or Chemo/RT is primary option
high survival rate
looking to preserve anal sphincter (instead of removal -> colostomy bag)
surgery for very early disease or post RT for recurrence
Chemo Radiosensiting (5FU &/or mitomycin C)
What are the standard doses for anal cancer?
Ph 1: pelvis & nodes (30.6 - 45Gy with chemo) (2-4 fields)
Ph 2: Primary site (add 24.4-
14.4Gy) (include superficial inguinal nodes)
What is the typical set-up for anal cancer?
mainly prone + belly board
can be supine
What is the typical set-up for anal cancer?
mainly prone + belly board
