Intraoperative radiation therapy for colon and rectal cancers: a clinical review
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REVIEW
Open Access
Intraoperative radiation therapy for colon and rectal cancers: a clinical review Michael G. Haddock
Abstract Although there have been significant advances in the adjuvant therapy of colorectal cancer, results for patients have historically been poor when complete resection is unlikely or not possible. Similarly, locally recurrent colorectal cancer patients often experience significant tumor related morbidity and disease control and long term survival have historically been poor with standard therapies. Intraoperative radiation therapy (IORT) has been proposed as a possible tool for dose escalation in patients with locally advanced colorectal cancer. For patients with locally advanced primary or recurrent colon cancer, the absence of prospective controlled trials limits the ability to draw definitive conclusions in completely resected patients. In subtotally resected patients, the available evidence is consistent with marked improvements in disease control and survival compared to historical controls. For patients with locally advanced primary or recurrent rectal cancer, a relatively large body of evidence suggests improved disease control and survival, especially in subtotally resected patients, with the addition of IORT to moderate dose external beam radiation (EBRT) and chemotherapy. The most important prognostic factor in nearly all series is the completeness of surgical resection. Many previously irradiated patients may be carefully re-treated with radiation and IORT in addition to chemotherapy resulting in long term survival in more than 25% of patients. Peripheral nerve is dose limiting for IORT and patients receiving 15 Gy or more are at higher risk. IORT is a useful tool when dose escalation beyond EBRT tolerance limits is required for acceptable local control in patients with locally advanced primary or recurrent colorectal cancer. Previously irradiated patients should not be excluded from treatment consideration. Keywords: Colon cancer, Rectal cancer, IORT
Introduction Despite the realized therapeutic gains, colorectal cancer remains the 5th leading cause of cancer death in the world with more than 1 million new cases and more than 600,000 deaths per year [1]. Screening for colorectal cancer is an effective tool and where implemented has resulted in declines in cancer mortality [2]. When diagnosed at an early stage, the prognosis following surgical based treatment of colorectal cancer is excellent. However, for patients with locally advanced primary or recurrent colon cancer, often unresectable for cure, recurrence rates are high and survival is poor with conventional therapy [3]. Similarly, very locally advanced primary or recurrent rectal cancer patients have high
Correspondence: [email protected] Department of Radiation Oncology, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA
rates of local and distant relapse and poor survival outcomes [4–6]. The concept of using radiation therapy during an operation to treat a malignancy originated more than 100 years ago and e
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