Colon and Rectum. Anatomic Considerations and Patterns of Spread. Rectum . 12 to 15 cm in length from the rectosigmoid junction to the puborectalis ring upper third middle third (posterior border of the rectouterine pouch or rectovesical space) lowest third no serosal barrier.
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bowel habits, weakness, intermittent abdominal pain, nausea, and vomiting.
The persistence of such symptoms as well as any evidence of iron deficiency anemia should be investigated
exophytic ,iron deficiency anemia
deeply invasive, annular, and accompanied by obstruction and rectal bleeding
Although screening methods can detect colorectal cancer at an early stage, <40% of patients are diagnosed with early disease, likely reflecting low rates of disease awareness as well as the infrequency of screening in eligible candidates
average 5-year survival
margin negative resection (66%)
microscopic residual (47%)
gross residual (23%).
The 5-year rate of local control was 96% for patients receiving 50 to 55 Gy versus 76% for patients receiving <50 Gy
To assess whether the addition of radiation therapy to adjuvant chemotherapy would result in superior survival and local regional failure rates in resected, high-risk colon cancer patients, the U.S. Intergroup initiated a randomized prospective trial in 1992 (103). In this trial, patients with resected colon cancer were randomized to postoperative irradiation with 5-FU and levamisole or 5-FU and levamisole alone. Eligibility criteria included margin negative tumors with adherence to or invasion of surrounding structures (i.e., T4N0 or N+ disease, excluding peritoneal invasion) or tumors arising in the ascending or descending colon with metastatic regional nodes (T3N+). Patients were randomized to receive (a) weekly 5-FU combined with levamisole for 12 months' duration or (b) 5-FU and levamisole for 12 months with combined radiation therapy and chemotherapy beginning 1 month after the first 5-FU administration. The recommended total radiation dose was 45 Gy in 25 fractions over 5 weeks with an optional 5.4 Gy boost.
11% receiving IOERT plus EBRT versus 82% EBRT only
76% for patients receiving IOERT 26% for patients receiving EBRT alone]
45 Gy in 25 fractions of 1.8 Gy per fraction (primary tumor and at-risk tissues)
Reduced fields to 50 Gy
T4 tumors( a total dose of 54 to 60 Gy)
CHRT →S± IOERT+CHT
A similar approach would be reasonable for patients with locally recurrent cancers or with regional nodal relapse
with 5-FU (1,000 mg for meter squared on days 1 to 3 and 29 to 31)
a 25% local failure rate
40% to 50% overall survival,
local failure rate of 10% to 15%
overall survival rate of 50% to 60%.
nausea, vomiting, diarrhea , stomatitis with mucosal ulceration , hematological toxicity
diarrhea, hand/foot syndrome ,Chronic bowel injury (25% )
rectal urgency with frequent bowel movements
The initial CTV should include macroscopic disease with an approximately 2-cm margin in mesentery and within the course of the large bowel(the initial CTV should include rectal mesentery and nodal regions at risk)
less than T4 disease
adequate margins >1 cm
Ten to 12.5 Gy for complete resection
12.5 to 15 Gy for microscopic residual
17.5 to 20 Gy for gross residual disease.