Colorectal Cancer

Colonoscopy is still the best test available for colon cancer detection, finding the vast majority of cancers and polyps, though not perfect.

Serrated adenomas (previously misclassified as hyperplastic polyps) have good evidence of genetic predisposition and tie into many family cancer syndromes.

Serrated polyps have a very high risk of cancer and require family assessment to determine if patients have a family cancer syndrome.

Serrated adenomas are often flat and difficult to see; retroflexion in the cecum is useful because they are often on the inferior or superior side of the valve or on folds.

Six centimeters from the anal verge can be mid-rectum in a small patient (90-pound, 80-year-old female) or close to the dentate line in a large patient (6'6", 300 pounds).

Distal margin requirements for rectal resection: 5 centimeters if possible, 2 centimeters if possible, and for very lowest tumors perhaps 1 centimeter as long as they are not poorly differentiated.

Historical local recurrence rates for rectal cancer from good institutions were 20 to 38 percent, with some up to 50 percent.

With optimized surgery, imaging, and patient selection, local recurrence rates for rectal cancer should be under 10 percent; Cleveland Clinic's rate over the last 10 years was about 3 percent.

For total mesorectal excision, the circumferential resection margin should be one to two millimeters; if threatened, this is an indication for neoadjuvant therapy or extended resection.

A total mesorectal excision can be performed with about 5 milliliters of blood loss because it is a bloodless plane; bleeding indicates being outside that plane or in the wrong plane.

Most accepted guidelines for neoadjuvant therapy in rectal cancer are for tumors that are T3 (outside the wall of the rectum) or node positive.

For node-negative T1 or T2 rectal tumors (stage one), particularly if upper third, neoadjuvant therapy can be omitted.

MRI is probably 90 to mid-90s percent accurate at T staging and high 80s to 90% accurate for nodal staging in rectal cancer.

Endoscopic ultrasound is much more operator dependent and probably only 70% accurate for predicting nodal involvement in rectal cancer.

Historical local recurrence rates for transanally excised rectal cancers were about 18%, remarkably consistent across outcome data from several big centers.

Transanal resection is generally appropriate for tumors less than a third of the circumference, ideally less than two centimeters, that are T1.

For young, curable patients, most surgeons favor radical resection over transanal resection; transanal resection is generally kept for patients unfit for rectal resection or those whose tumor is so close to the dentate line that a permanent stoma would be required.

For rectal cancer, full-thickness excision is required; ESD (endoscopic submucosal dissection) would never be done for a proven cancer, only for benign polyps.

In Europe, short-course radiation is five times five gray given over five days, with surgery about one to two weeks later.

In the U.S., long-course radiation is 40 to 45 gray given with chemotherapy over six weeks, followed by a six to eight week waiting period.

Twenty-five gray over a short period is radiotherapeutically equivalent to 40 to 45 gray over a longer period, but longer course can make a big difference for tumor response and physical downstaging.

For colon cancer surgery, goals include at least a 5 centimeter proximal and distal margin (usually determined by blood supply) and at least 12 lymph nodes, with many surgeons hoping for at least 16.

Total mesocolic excision should be performed in the plane between the embryological peritoneum of the retroperitoneum (Toldt's fascia) and the embryological peritoneum on the mesocolon, keeping the mesocolon complete.

Scandinavian data showed local recurrence rates for colon cancer were even higher than for rectal cancer (which was high 20s percent) because they realized they weren't doing adequate colon cancer surgery.

For a cecal tumor or lesion near the ileocecal valve, 10 centimeters of small bowel should be taken; for mid-ascending colon, 5 centimeters should be taken.

Extracorporeal stapled anastomosis for right colectomy has reported leak rates of 0.8% over 1,000 cases at Cleveland Clinic.

Genetic workup should be considered for patients with cancer under age 40, first-degree relatives with cancer, multiple cancers in a family, or non-GI cancers in a family.

Genetic findings may change the surgical operation: a patient with a right colon cancer plus multiple polyps or significant family history may be better served with a subtotal colectomy rather than segmental resection.