Rectal cancer

There is currently no definitive role for adjuvant radiation in colon cancer. However, patients who receive surgery for rectal cancer receive radiation therapy to reduce local tumor recurrence. Adjuvant radiation plus chemotherapy is considered standard treatment for patients with stage II or III rectal cancer after the surgical procedure is complete.17 Preoperative radiation may be used to reduce the initial size of rectal cancers in order to make the surgical procedure easier. 

Adjuvant chemotherapy is administered after tumor resection to decrease relapse rates and improve survival in patients with colon cancer by eliminating micrometastatic disease that is undetected on imaging studies. Patients diagnosed with stage I colon or rectal cancer usually are cured by surgical resection, and adjuvant chemotherapy is not indicated in these patients.16 The role of adjuvant... 

Although often treated similarly to colon cancer, there are some important differences in the treatment of rectal cancer compared with colon cancer, especially in the adjuvant setting and the role of radiation. Rectal cancer involves tumors found in distal 15 cm of the large bowel and, as such, is very distinct from colon cancer in that it may recur both locally and dis-tally. The higher incidence of local failure and poorer overall... 

Another unique aspect of rectal cancer is the use of neoadjuvant therapy. Preoperative radiation with or without chemotherapy is given to downstage the tumor prior to surgical resection to improve sphincter preservation by making the surgical procedure easier to perform. The issue of preoperative versus postoperative radiation is a subject of debate and investigation in the United States and will require further data to determine the superiority of one method over the other. 

VlLLAFRANCA E, OKRUZHNOV Y, DOMIN-guez MA et al. Polymorphisms of the repeated sequences in the enhancer region of the thymidylate synthase gene promoter may predict downstaging after preoperative chemoradiation in rectal cancer. J Clin Oncol 2001 19 1779-1786. 

Johnston PG, Fisher ER, Rockette HE, Fisher B, Wolmark N, Drake JC, Chabner BA, Allegra CJ. The role of thymidylate synthase expression in prognosis and outcome of adjuvant chemotherapy in patients with rectal cancer. 

However, some large cohort studies (Michels and others 2000 Voorips and others 2000) showed no appreciable association between fruit and vegetable intake and colon and rectal cancer. 

Michels KB, Giovannucci E, Joshipura KJ, Rosner BA, Stampfer MJ, Fuchs CS, Codlitz GA, Speizer FE and Willett W. 2000. Prospective study of and incidence of colon and rectal cancers. J Natl Cancer Inst... 

Voorips LE, Goldbohm RA, van Poppel G, Shumans F, Hermus RJ and van den Brandt PA. 2000. Vegetable and fruit consumption and risk of colon and rectal cancer in a prospective cohort study. Am J Epidemiol 152 1081-1092. 

Surgery for rectal cancer depends on the area involved. Although less than 33% of these patients require permanent colostomy, frequent complications include urinary retention, incontinence, impotence, andlocoregional recurrence. 

Common complications of surgery for both colon and rectal cancer include infection, anastomotic leakage, obstruction, adhesions, and malabsorption syndromes. 

RT can be administered with curative surgical resection to prevent local recurrence of rectal cancer, before surgery to shrink a rectal tumor and make it operable, or in advanced or metastatic disease to alleviate symptoms. Adjuvant RT, however, does not have a definitive role in colon cancer because recurrences are usually extrapelvic. 

The goal of adjuvant RT for rectal cancer is to decrease local tumor recurrence after surgery, preserve the sphincter, and, with preoperative radiotherapy, improve resectability. 

FU enhances the cytotoxic effects of RT. Compared with surgery alone, the combination of adjuvant 5-FU and RT reduces local and distant tumor recurrences and improves survival in stages II and III rectal cancer. 

No reduction in risk for breast, lung, gastric, colon, or rectal cancer when used for less than... 

A phase I study of Xeloda in combination with XRT in rectal cancer is in the adjuvant, neoadjuvant, and palliative settings (71-73). The DLT of the combination is hand-foot syndrome and mild to moderate leukopenia, diarrhea, and local skin reaction (71-73). The recommended dose for phase 2 studies is Xeloda 825 mg/m2 twice daily without interruption in combination with standard dose of radiation. Promising activity has been demonstrated in neoadjuvant therapy with six objective responses in seven evaluable patients including one pathological confirmed CR. 

The use of 5-FU in combination with radiotherapy has shown improved survival in various malignancies including unresectable pancreatic cancer, resectable pancreatic cancer, Dukes B2 and C rectal cancer, esophageal cancer, and hepatobiliary cancer (Table 2). Similarly, 5-FU with concurrent radiation has also been used for organ preservation in different tumors involving bladder cancer, anal cancer, and laryngeal cancer (Table 3). 

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