Post on 25-Dec-2015
Digestive System – Anatomy/Physiology
Purpose of digestive system: to change food (nutrients) into energy for storage or body use
Primary Organs: esophagus, stomach, small/large intestine
Other digestive system organs assist in digestion - liver, gallbladder, pancreas
Colon (large intestine), rectum and anus carry waste products (non-nutrients) through to excretion
ADAM and Medline Plus.
• Purpose of colon: Water absorption from indigestible food • Parts of colon in order of passage: ascending, transverse, descending, sigmoid • Ileocecal valve of small intestine passes waste into large intestine at cecum. • Waste excreted from rectum through anal canal - anus
ADAM, Medline Plus
Large intestine - long hollow organ lined with mucous membrane Muscle wraps around length of large intestine, assisting the passage of food through organ to rectum, anal canal, and anus
Adam, Medline Plus
What is Colon Cancer or Colorectal Cancer (CRC)?Disease in which malignant cells form in
tissues of colonColon – first 6 feet of large bowel/intestineRectum – last 6 inches of anal canalAppendix – also a part of colonUsually adenocarcinoma – 95% of all cases
Other typesLymphomaCarcinoid tumorsMelanomsSarcoma
Medline Plus, ACS
Epidemiology of CRCThird most common form of cancer in males and
females2nd most common cause of death among US males
and females combined10% of male cancer deaths annually
Greater proportion of cancer deaths - only in lung/bronchus (31%)
10% of female cancer deaths annuallyGreater proportion of cancer deaths - only in
lung/bronchus (26%) & breast (15%)Second leading cause of cancer deaths in Western
world655,000 deaths per year worldwide148,540 will develop annually (2008 estimate)
108,070 in colon; 40,740 in rectum49,960 deaths per year in US
Medline Plus, ACS
SymptomsDepends on location of tumor in bowelWhether cancer has metastasizedMany symptoms may also occur in other
diseases, so symptoms are not definitiveThree kinds of symptoms
LocalConstitutionalMetastatic
Medline Plus, ACS
Local symptoms (continued)Tumor large enough to fully occlude opening of
bowel – bowel obstructionConstipationAbdominal painTenderness in lower abdomenDistention of abdomenEmesisPerforation and peritonitisLow back pain
AdvancedNoticed on palpationSeen at physical examMetastatic to bladder – blood or air in urineMetastatic to female reproductive organs – vaginal
discharge
Medline Plus, ACS
Constitutional Symptoms
Iron deficiency anemia if chronic undetected bleedingFatigueIrregular heart beat - palpatationsPaleness of skinWeight lossDecreased appetiteFever of unknown originThrombosis – usually DVT
Medline Plus, ACS
Symptoms of Metastatic CRCUsually spreads to liverJaundiceAbdominal painBile duct obstruction
Pale stools due to biliary obstruction
Medline Plus, ACS
Risk Factors Age over 50
More than 90% of CRC diagnosed in those > 50 yearsMost CRC appears in 60s and 70sCases under 50 rare unless genetic predisposition among younger
family membersAA highest rate of all racial/ethnic groups in US; Eastern European
Jews History of cancer
Women with previously diagnosed/treated ovarian, uterine, or breast cancer
Personal diagnosis and treatment for CRCHistory of polyps, especially benign polyps - adenomatous
Inflammatory bowel disease – History of chronic ulcerative colitis in 1%; Chron’s
Obesity Heavy alcohol use Family History
Less than 10% caused by geneticsClose relative diagnosed before 55 years of ageMultiple relatives diagnosed with CRC
Medline Plus
Risk Factors (continued)Smoking
Smokers more likely to die of CRC than non-smokersFemale smokers more than 40% more likely to die of
CRC than non-smokersMale smokers – increased risk (30%) compared to
non-smokersDiet low in fruits/vegetables, fish, poultry - possible
Unclear fiber effectDiet high in fat, red and/or processed meat -
possiblePhysical inactivityVirus – HPVLow levels of selenium
Medline Plus
PreventionDeath rate dropped in last 15 yearsTakes many years to develop CRCEarly detection of polyps and CRC – criticalMost CRC develops from easily removable
polypsUndetected polyps grow through lining and layer of
colon wall and rectumEarly screening could significantly reduce
mortalityScreening rates low Almost all men and women older than 50 should
screen
ACS
Diagnosis and ScreeningInitial DRE – inspection of distal parts of rectumFOBT – tests for trace amounts of blood in stool -
annuallyGuiac (chemical)Immunochemical – superior to FOBTMust be used with endoscopyFalse negatives and positives
EndoscopySigmoidoscopy – inspection of rectum & lower third of
colon with lighted probe and inserting air – every 5 years
Colonoscopy – inspection of rectum and all parts of colon; polyp removal and biopsy – every 3 years
Double contrast barium enema for detection in large intestine
Complete blood count to check for anemia
ACS
PrognosisDepends on stage of cancer when detectedIf detected and treated early, most patients
survive for 5 years 5-year survival rate drops if not detected
early enough and cancer has metastasizedIf CRC does not return in 5 years,
considered curedStages 1-3 potentially curableStage 4 not curable in most cases
ACS
Staging• Depends on size of tumor and degree of
penetration• Stage 0 – very early – tumor on mucosa – inner-
most colon layers• Stage I: Metastasized into sub-mucosa – inner
layers• T1N0M0 – In sub-mucosa - inner layers of the colon • T2N0M0 – in muscularis propria
• Stage II: Metastasized into colon’s muscle wall • A-T3N0M0 - In sub-serosa or beyond (no organs)• B-T4N0M0 – in adjacent organs after perforates peritoneum
• Stage III: Metastasized into nearby lymph nodes• A -T1-2N1M0 – in 1-3 regional lymph nodes (T1 or T2)• B- T3-4 N1M0 – in 1-3 regional lymph nodes (T3 or T4)• C-Any T, N2M0- 4 or more regional lymph nodes. Any T
• Stage IV: Metastasized to remote organs • Any T, Any N, M1 – remote metastases. Any T, any N
ACS
TreatmentDepends on stage of cancerChoices:
Surgery – primary treatmentRadiation (mostly used in Stage 3 rectal
cancer); also used with chemotherapy in other stages
Treatment by stageStage 0 – removal during colonoscopyStage 1, 2, 3 – more extensive surgeryStage 4 – chemotherapyMetastatic liver cancer: surgery,
chemotherapy/radiation directed to liver, cryotherapy, ablation
ACS