Adenocarcinoma of the Colon and Rectum Flashcards
One of ealiest mutations in sporadic cancers is
the inactivation of of the adenomatous polyposis coli (APC) gene on chromosome 5q
Microsatellite instability (MSI) is
an alternative pathway for genomic instability and subsequent colorectal carcinogenesis
MSI arises from
defects in mismatch repair genes
MSI in hereditary nonpolyposis colorectal cancer (HNPCC) is most commonly attributable to germline mutations in
hMLH1 and hMSH2 genes
The vast majority of colorectal cancers (CRCs) are
sporadic (5% are associated with known genetic syndromes)
Most common genetic syndrome associated with CRC is
HNPCC, which acounts for the majority of patients wiht familial CRC
The lifetime risk of CRC for patients with UC is
3.7%
The Dukes classification was initially develooped as a
prognostic tool for rectal cancer in the 1930s
The modified Astler-Coller system
a modified Dukes classification introduced in the 1950s
The TNM classification is
the preferred staging system
TNM - Primary tumor (T)
T0 - no evidence of primary tumor, Tis - carcinoma-in-situ (intraepithelial or invasion of lamina propia), T1 - tumor invades submucosa, T2 - tumor invades muscularis propria, T3 - tumor invades through muscularis propia, T4 - tumor invades other organs or perforated visceral peritoneum
TNM - Regional lumph nodes (N)
N0 - no regional LN metastases, N1 - metastases in 1 to 3 regional LNs, N2 - metastases in 4 or more regional LNs
TNM - Distant metastasis (M)
M0 - no distant metastasis, M1 - distant metastasis
Stage 0 CRC
Tis, N0, M0
Stage I CRC
T1 or T2, N0, M0
Stage IIA CRC
T3, N0, M0
Stage IIB CRC
T4, N0, M0
Stage IIIA CRC
T1 or T2, N1, MO
Stage IIIB CRC
T3 or T4, N1, M0
Stage IIIC CRC
Any T, N2, M0
Stage IV CRC
Any T, Any N, M1
Alternative to colonoscopy
air-contrast barium enema
Mainstay of therapy for colon cancer
surgery with curative intent
An adequate margin of resection is ___ cm of normal bowel on each side of the tumor
5 cm
For tumors of the cecum and ascending colon, a
right hemicolectomy that includes the right branch of the middle colic artery at its origin should be performed
For tumors of the hepatic flexure, an
extended right colectomy that includes the entire middle colic artery
For tumors of the transverse colon, an
extended right or left colectomy or a transverse colectomy may be performed
For tumors of the splenic flexure region, a
left hemicolectomy is performed
For sigmoid tumors, a
sigmoid colectomy is performed
The incidence of synchronous CRCs is reported to range from
3 to 5 %
Postoperative systemic adjuvant therapy is
the standard of care in patients with stage III disease
With rectal cancer, surgical treatment alone results in recurrence rates of
16.2% after LAR and 19.3 after APR
Anastomotic leakage rates vary widely after radical rectal resection
10 to 30%
Preoperative chemoradiation therapy ___ been shown to increase anastomotic leakage rates.
has not
Criteria for transanal excision (TAE):
lesion < 4 cm in diameter, < 1/3 circumference of rectum, < 8 cm from anal verge
Adequate distal margin for rectal cancer
2 to 5 cm
Peritoneal carcinomatosis develops in ~
13% of all CRC patients
Recurrence surveillance recommendations
CEA levels every 2-3 months for 2 years then every 3-6 months for 3 years then annualy; clinical exam every 3 to 6 months for 3 years than annually; colonoscopy perioperatively then every 3 to 5 years
The most common sites of metastasis in CRC patients are
liver and peritoneal cavity
