Colorectal Ca Flashcards
what is CRC? define
colorectal cancer
adenocarcinoma is most common
- other subtypes of adenocarcinoma exist
other non-adenocarcinoma cancers include:
- carcinoid tumours
- Gastrointestinal stromal tumours
- NHL
- sarcomas
what is a colorectal polyp?
it’s a protuberance into the lumen of a normally flat colonic mucosa (inwards)
explain non-neoplastic vs neoplastic examples of colorectal polyps
non-neoplastic ➔ usually a hyperplastic situation (most common
- mucosal polyps and hamartomas are also potential histological findings
neoplastic polyps are things like adenomas ➔ they are premalignant and can invade into the submucosa
- histological cell type informs the invasiveness of the polyp (villous is most vs tubular is less)
- tubular polyps are more common vs villous
epi of crc?
3rd most common cancer (lung > breast > colon)
in general the incidence of CRC is decreasing however the age at dx is getting younger
more common in Caucasians
RF for CRC
- fhx of CRC, breast cancer, or hereditary cancer syndromes (familial adenomatous polyposis and lynch syndrome)
- personal hx of cancer
- inflammatory bowel diseases
- celiac
- increased age (>50Y)
- abdo/pelvic radiation
- comorbidities: DM< uncontrolled acromegaly disease, LT immunosuppresants, and obesity
- diet: processed meat and food and low-fiber diet
- smoking and alcohol
- androgen deprivation therapy (prostate ca tx)
common sites of CRC mets?
liver, lung, bone, brain
general patho of how colorectal
- collection of cell line mutation (can be somatic or germline via the hereditary cancer syndromes)
- may result in precancerous polyps (adenomatous polyp)
- over time (10-15Y) more mutations accumulate which can result in dyplastic changes
- can evolve into an invasive carcinoma
what are 2 of the 3 major molecular pathways that result in CRC?
- chromosomal instability
- damaged mismatch repair mechanisms
- hypermethyaltion of tumour suppressor genes
common genes involved in CRC
- RAS
- APC
- TP53
- MMR genes
what are red flags for crc?
- iron deficiency anemia in older males or postmenopausal females
- pencil stools
- melena
- bright red blood per rectum
what are some general s/s of CRC?
- hematochezia
- melena
- abdo pain
- changes in BM
- tenesmus
- constitutional s/s: fatigue, wt loss
- s/s of obstruction
P/E: physical mass on DRE or RLQ w/ a R colon mass
walk me through screening recommendations for CRC
average risk: start at 50Y-74Y, fecal immunochemical test every 2 yearsor sigmoidoscopy
high risk: first degree relative ➔ start at 50Y or 10Y before the age of dx; colonoscopy every 5Y (if relative was <60Y) or 10Y (if relative was >60Y)
how would you dx a colon cancer?
colonosocpy w/biopsy
how do you work up a dx colorectal cancer
- CBC with diff
- ferritin
- electrolytes and extended
- creatinine and urea
- liver: ALT/ALP bilirubin
- CEA - tumour marker – baseline for tx response
- coagulation - PT/INR and aPPT re potential bleeding
imaging
- baseline CT CAP w/ contrast to look for mets
how do you tx crc?
- refer to surg onc and med onc
early disease: resection w/ LN and mesentery
consider neoadjuvant therapy if tumour is large ➔ chemoradiation (alkylating agent +/- antimetabolite)
adjuvant therapy of chemo: alklylating agent +/- antimetabolite
with stage 4 – palliative
- procedures to help with s/s management ➔ obstruction (ostomy), bleeding/pain (radiation)
organize follow-up surveillance with CT CAP and CEA and colonoscopy every 1, 3, and 5Y
