RESUMO
AIMS AND BACKGROUND: The study analyzed the potential contribution of positron emission tomography (PET) in patient selection for radiotherapy and in radiation therapy planning. METHODS: Eighty-seven patients with a histological cancer diagnosis were accrued for the study from December 2000 to December 2001. Demographic characteristics included a median age of 54 years and male/female ratio of 51/36. All patients staged by conventional workup who were candidates for radiotherapy had PET imaging and were allocated to a conventional "pre/post-PET stage". The treatment protocol and the shape and/or size of the portals was directly related to PET results. We examined 26 lung cancers, 15 gastrointestinal tumors, 22 genitourinary cancers and 24 hematologic malignancies. RESULTS: In the lung cancer group, the stage was modified in 10/26 patients (38.5%) by PET, with a change in management in 13 (50%) and a change in radiotherapy planning in 6 (23.1%). In the hematological group, stage was modified by PET in 8/24 cases (33.3%), with a change in treatment strategy in 9 (37.5%) and a change in radiotherapy planning in 3 (12.5%). In the gastrointestinal group, the stage was modified by PET in 2/15 cases (13.4%), with a change inn treatment strategy in 4 (26.7%) and a change in the decision for radiotherapy in 8 (no radiotherapy in 53.3%). In the mixed group (genitourinary, breast and other), the stage was modified by PET in 6/22 cases (27.3%), with a change in treatment strategy in 11 (50%) and a very low rate of change in radiotherapy planning. CONCLUSIONS: PET contributed to a modification of stage in 26/87 patients (30%), to a changing in treatment strategy in 37/87 (42.5%), and to a substantial change of the shape and/or size of radiotherapy portals in 13/43 (30%) who underwent radiotherapy.