Monday, July 12, 2010

Preoperative radiotherapy for colorectal cancer radiotherapy

Another cancer radiotherapy is the use of preoperative radiotherapy.

Preoperative radiotherapy has the following advantages: a good blood supply of the target cells, high ammonia level in Asia, on the radiation sensitivity of high clinical outcome. Radiation can shrink tumors, lower lesions of (down-staging), to enhance tumor resection rate, not only undercut rate, rectal success rate has improved markedly. Small intestine were significantly narrowed the scope of exposure, the incidence of radiation damage of small intestine was significantly reduced. Recovery occurred after continuous intestinal radiation proctitis, anastomotic stricture, and intestinal dysfunction, the chances of complications such as greatly reduced. The sacral fascia fibrosis after radiation thickening of the vascular protective effect of strengthening the presacral, presacral vein surgery less chance of injury, especially for locally advanced disease, surgery safety relative to preoperative radiotherapy there are so many advantages, but there is a fatal drawback, may be carried out as part of radiation therapy without radiation therapy, which is treated too far, because of radiation, after all, has some damage to normal cells.

In addition, the current special emphasis on the patient before surgery on the correct assessment of disease through clinical examination, B-cavity, pelvic CT / MRI, a series of simulated intestinal microscopic examination of the diseased patients to make more accurate assessment of the operation provide the basis before radiotherapy, to avoid unnecessary and inappropriate treatment.

From the mid-70s has at least 12 on the resectability of rectal cancer with preoperative radiotherapy randomized study reported, but no application of full dose (≥ 45Gy), the majority of the radiation technique used and not satisfied, from radiation to surgery after not enough time interval of (4 to 6 weeks), resulting in only six reported local recurrence rate was statistically significant.

Sweden, a group of reports (SRCT) 1183 patients were receiving surgery alone or surgery plus short-term preoperative radiotherapy, radiation dose of 25Gy, in 5 days 3 or 4 applied radiation field, radiotherapy after surgery a week showed the local recurrence rate significantly decreased (27% vs1% P <0.001), 5-year survival rate was significantly increased ((48% vs58% P = 0.004). But the second group received AP resection is the same as the ratio of ((59% vs58%), Therefore, the Swedish preoperative radiotherapy 5 days a week program did not agree with the U.S. counterparts, who believe that this program has several shortcomings: ① chemotherapy is not appropriate at the same time; ② not help to improve the success rate of sphincter preserving surgery; ③ increased incidence of postoperative complications. Paty so that the greatest advantage of preoperative radiotherapy is beneficial to improve the success rate of sphincter preserving surgery.

Minsky reported 30 cases of rectal cancer from the anal margin of 1.5-6cm of the original development of AP resection, in the full dose by 5040cGy after preoperative radiotherapy, 83% completed a low anterior resection for colon-anal anastomosis.

Rouanet and other similarly reported low rectal cancer after preoperative radiotherapy can do 78% of rectal surgery. This preoperative radiotherapy, surgery postponed at least 8-10 weeks, increased the risk of tumor spread far, this has recently carried out many scholars combined preoperative chemotherapy in the neoadjuvant treatment, short-term effect is significant again with postoperative chemotherapy, to prevent the spread, the 5-year survival is possible in theory, of course, the final conclusion will wait for the results of long-term follow-up to confirm.

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