EXTERNAL-BEAM PLUS INTRAOPERATIVE IRRADIATION FOR GASTROINTESTINAL CANCERS

Although useful palliation can often be achieved when external beam ir radiation and chemotherapy are used to treat,locally advanced gastroin testinal malignancies, local control and long-term survival are infreq uent in view of the limited tolerance of surrounding organs and tissue s. In view of dose limitations of external beam irradiation, intraoper ative irradiation (IORT) with electrons has been used as a supplement to external treatment in an attempt to improve the therapeutic ratio o f local control versus complications. An IORT dose of 10 to 20 Gy has been combined with fractionated external beam doses of 45 to 55 Gy in 1.8 Gy fractions in studies performed in the United States, Japan, Eur ope, and Scandinavian countries. In this paper the indications for and the results of aggressive combined techniques that include IORT are d iscussed. Results obtained with external beam techniques alone or with chemotherapy and resection are presented by site to demonstrate the n eed for higher doses of irradiation. When results from IORT series are compared to standard treatment with regard to disease control and sur vival, local control appears better with locally advanced colorectal, gastric, and pancreatic cancer; and survival appears better with color ectal +/- biliary cancers. With pancreatic cancer, improvements in loc al control do not translate into increased survival in view of the hig h incidence of subsequent liver and peritoneal failures. Implications for future strategies in all sites are discussed.