COLUMBUS, Ohio--Rectal cancer is treated with a wide variety of
operations and adjuvant therapy. This variety makes extensive
preoperative evaluation mandatory, said Karamjit Khanduja, MD, chief
of the Division of Colon and Rectal Surgery, Mt. Carmel Health,
In a presentation at the Ohio State University-James Cancer Hospital
and Research Institute 4th Annual Oncology Update, he said that
endorectal ultrasound, a relatively new tool, is rapidly becoming a
standard method of assessing tumors, while several standard
laboratory tests are proving less crucial than once thought in
evaluating rectal cancer.
Recent advances in the treatment of rectal cancer have broadened the
number of surgical options available, including total mesorectal
excision and transanal endoscopic microsurgery. Chemoradiation
therapy, often given after surgery, has also proved beneficial when
performed before an operation, Dr. Khanduja said.
To choose among the many treatment options available, the surgeon
must carefully evaluate patient factors, tumor characteristics, and
the extent of distant metastasis. A thorough, detailed staging of the
tumor is essential. To determine whether preoperative chemoradiation
is appropriate, for example, the surgeon must carefully determine the
extent of local disease.
Colon cancer, by contrast, has fewer treatment options and, thus,
requires less preoperative evaluation. Limited staging is adequate to
make a decision regarding treatment for colon cancer, he said.
Endorectal ultrasound with rigid sigmoidoscopy should be used to
determine which tumors are good candidates for preoperative
chemoradiation therapy (Figures 1A,
1B, and 2). "If you want to do preoperative chemoradiation,
then you must do ultrasound," Dr. Khanduja said.
Ultrasounds accuracy range for tumor size is 80% to 95%, while
its accuracy for lymph node involvement is 60% to 80%. Accuracy
improves with experience.
Preoperative chemoradiation is appropriate for UT3 and UT3N1 or N2
rectal cancers (U = by ultrasound staging), Dr. Khanduja said.
Studies have shown that preoperative chemoradiation therapy is safe,
results in the downstaging of tumors, and increases the surgeons
ability to perform sphincter-saving operations. In 8% to 25% of
patients, it eradicates the tumor completely, he said, citing the
progress report of NSABP Protocol R-03 [Dis Colon Rectum
A CT scan is necessary to determine the presence of metastatic liver
disease. The decision of whether to provide preoperative
chemoradiation will be guided by the CT scan results. "I find
that in staging rectal cancers, especially large tumors, the CT scan
complements the ultrasound," Dr. Khanduja said. He noted that
preoperative CT is unnecessary in most cases of colon cancer. A CT
scan can also provide information regarding renal function status.
By shrinking tumors, preoperative therapy can increase the number of
sphincter-saving surgeries performed. Thus, he said, determining the
functional status of the anal sphincter, and the feasibility of a
sphincter-saving operation, is an essential part of the preoperative evaluation.
If CT is done, than no additional advantage is gained by performing
magnetic resonance imaging (MRI), since MRI of rectal cancer has
results similar to those of CT scans and is not accurate in
determining depth of wall involvement or presence of adenopathy. The
routine use of MRI is not recommended, Dr. Khanduja said. He did
point out that the addition of an endorectal surface coil has been
shown to improve the procedures accuracy from 50% to almost 85%.
Measuring the level of the tumor marker CEA preoperatively is
"very essential," Dr. Khanduja said. It usually returns to
normal within 1 month of surgery. Persistent elevation implies
residual disease, while a fall to normal after surgery followed by a
consistent steady rise indicates recurrent cancer in up to 95% of patients.
Preoperative tests that are less important to conduct include liver
function studies and routine genitourinary assessment. Liver function
studies, whether elevated or not, correlate poorly with actual liver
metastasis. CT scans are the best way to measure distant disease, he said.
Excretory urography results are abnormal in 26% to 43% of patients,
but are a poor predictor of genitourinary complications. Indeed,
regardless of whether the test is normal, abnormal, or not done, the
literature shows that the rate of genitourinary complications is the
same, Dr. Khanduja said. As a result, routine preoperative
genitourinary assessment is not recommended.