Pancreatic carcinoma treated with high-dose, small-volume irradiation.

Eighteen patients with unresectable ductal adenocarcinoma of the pancreas received definitive, high-dose, small-volume radiation therapy. All patients had at least one laparotomy, at which time a biopsy was obtained, radio-opaque clips were placed to define the extent of the gross tumor, and usually some form of bypass procedure was performed. External-beam irradiation was delivered from a 45-MV betatron to an area encompassing the clipped tumor volume plus a 1 to 2 cm margin. A three-field technique, employing opposed lateral 45-MV photon beams and an anterior "mixed beam" (50% 45-MV photons and 50% 15- to 35-MeV electrons), was used to treat 13 of the patients. The choice of electron energy used for these patients was based on the depth of the posterior margin of the target volume. Five patients were treated by either four-field "box" or three-field, 45-MV photon techniques. Minimum tumor dose was 6300-6700 rads delivered in 180-rad fractions in 7-9 weeks. With the three-field technique, all fields were treated daily; with the four-field technique, two fields were treated daily. The projected survival rate 12 months post idagnosis is 59%, with the median length of survival, 11.8 months. Seven patients are alive 11.5 to 57 months after diagnosis, all clinically free of disease. Treatment has been generally well tolerated, and there have been no severe late radiation complications. This therapeutic modality appears capable of producing improved palliation, if not offering definitive radiotherapeutic management of localized unresectable carcinoma of the pancreas.