Flashcards in CSS.46.RectalCancer Deck (43):
what percentage of all colorectal cancers are rectal cancer?
what age do most patients with rectal cancer present?
what is the frequency of synchronous adenomas with rectal cancer?
what is the frequency of synchronous colorectal cancers with rectal cancer?
why is the high frequency of synchronous cancers important in the evaluation of rectal cancer?
it's why complete colonoscopy is necessary prior to surgery
what is the anatomical boundary that differentiates colon cancer from rectal cancer?
colon cancer is above the peritoneal reflection and rectal cancer is below the peritoneal reflection, less than 12-15cm from the anal verge
what clinical factor determines the degree of rectal tumor fixity in the pelvis?
depth of penetration of primary lesion through the rectal wall, with mobile lesions cT1-cT2, tethered lesions cT3, and fixed lesions cT4
what is the difference in tumor staging cT1-cT4 vs pT1-pT4?
cT1-cT4: clinically defined, suspected stage before removing the tumor based on available info, may be inaccurate. pT1-pT4: pathologically-defined, based on after the tumor is removed
What is a cT1 rectal cancer?
lesions limited to the mucosa or submucosa
What is a cT2 rectal cancer?
lesions extending into muscularis propria
What is a cT3 rectal cancer?
lesions extending into perirectal fat or mesorectum
What is a cT4 rectal cancer?
lesions extending to surrounding anatomic structures: prostate, seminal vesicles, vagina
What rectal cancer level of invasion should you suspect if a patient has pain?
involvement of the external sphincter complex by the tumor
what are the two best imaging modalities for rectal cancer? what are their staging accuracy for the primary lesion and local LNs? What other imaging is indicated on workup of rectal CA?
ERUS and MRI. 90% accuracy for primary lesion, 80% for local LNs. Also get a CT-C/A/P to determine extent of disease
what subtypes of tumor are ERUS better at staging and which are better for MRI?
ERUS better for early lesions, MRI for very bulky lesions with possible invasion into surrounding organs
What is the difference in overall treatment strategy of Stage I, Stage II, and Stage III rectal cancer?
Stage I: surgery alone; Stage II/III: multimodal therapy including chemo, radiation, and surgery
should chemo and radiation for rectal cancer be delivered preop or postop?
what operative dissection technique should you use with mesorectal excision for resection of rectal cancer
sharp dissection along the embryonic planes between the visceral and parietal layers of endopelvic fascia ensures complete removal of the locoregional lymph nodes in the mesorectum, preserves autonomic nerve function, and results in reduced blood loss
describe the combined modality therapy to treat stage II-IV rectal cancer
5FU (fluorouracil) + chemo
what procedure should you perform after neoadjuvant chemo prior to surgery for rectal cancer?
proctoscopy to evaluate for interval mets and response of primary tumor to chemo
what is post-LAR syndrome?
post low anterior resection syndrome (stool frequency, urgency, and clustering)
what preoperative counseling should you provide for a patient prior to anorectal CA surgery?
possibility of diverting stoma (do preop ostomy marking), sexual dysfunction, bladder dysfunction, post-LAR syndrome, postop bowel function may take 1-2 years to normalize and may be permanently altered
should you perform a bowel prep prior to rectal cancer surgery?
what are the basic steps of LAR for rectal cancer excision (from positioning to resection of rectal tumor)
pt in dorsal lithotomy, DRE and irrigation; midline incision from pubis to umbilicus; search for mets to liver/peritoneum/small bowel; mobilize sigmoid along white line of toldt; ID L ureter & gonadal vessels; score peritoneum along superior rectal artery to base of IMA; ligate pedicle just distal to the takeoff of the left colic pedicle; score peritoneum bilaterally and along anterior peritoneal reflection; raise sigmoid mesentery off RP; retract rectum anteriorly; develop avascular plane btwn visceral and parietal endopelvic fascia; sharp dissection thru Waldeyer's fascia; lateral dissection of the pelvic floor adjacent to mesorectum; anterior dissection last to Denonvillier's fascia; then establish distal tumor transection site; 1cm distal margin with perpendicular division of mesorectum; clamp at distal site, irrigate distal rectum with a liter of saline; double staple with linear stapler
why do you start LAR with irrigation and DRE
to remove stool and check location of tumor
why do you score the peritoneum along the superior rectal artery to the base of the IMA?
helps maintain sympathetic autonomic nerves in the retroperitoneum
when is high ligation of the IMA indicated in LAR?
presence of bulky nodal disease; not a/w improved oncologic outcomes; can result in autonomic nerve injury
Where is Waldeyer's fascia located?
retrosacral fascia from S4 to rectum/mesorectum
why should you avoid blunt dissection of Waldeyer's fascia?
can tear the presacral fascia, causing bleeding into the mesorectum resulting in an incomplete nodal dissection
what are the margins to excise a tumor of the upper rectum?
continue dissection to 5cm below the rectal mass
what are the margins to excise a tumor of the mid to lower rectum?
dissection completed to the pelvic floor where the mesorectum ends, 1-2cm distal margin
what portions of the colon are used for reconstruction after excision of rectal CA with LAR?
sigmoid colon if well-vascularized or left colon
what are three maneuvers to help mobilize the descending colon?
splenic flexure mobilization, IMV division adjacent to the ligament of Treitz, IMA division
after mobilizing the descending colon, what are the final steps in LAR?
circular stapler used, anvil placed within opened bowel with pursestring stitch, anvil brought down to rectal staple line, anstomosis created with second staple line, ensure two rings of tissue are intact, verify with proctoscopy and insufflating the rectum while the pelvis is full of saline
what surgery should you consider for a very low anastomosis (< 6cm from the anal verge) and why
colonic J-pouch because it will improve short term bowel function
what two preoperative interventions may be required for patients with obstructive rectal cancer?
colonic stenting or colostomy prior to cancer resection
what type of resection should be performed for cT4 rectal cancer?
for bulky tumors with possible extension to surrounding structures (small bowel, ovary, bladder, vagina, prostate, seminal vesicle), perform en bloc resection
what should you do if a colorectal anastomosis has a small vs large anastomotic defect?
take down anastomoses with large defects; repair small defects with sutures; if the leak too small to be identified but is seen on insufflation with pelvic saline, consider a diverting stoma
what percentage of patients have an anastomotic leak after LAR? How does it present?
20%, presents 4-7 days postop with F, tachycardia, arrhythmia, tachypnea, or diffuse peritonitis
what are two risk factors for anastomotic leak s/p LAR?
low anastomoses within 7cm of anal verge, patients who have received anti angiogenic agent therapy (bevacizumab)
what is the rate of incontinence after LAR?
can be as high as 60%
what is the standard of care for chemotherapy timing for Stage III rectal cancer?