CLINICAL TARGET VOLUME LOCALIZATION USING CONVENTIONAL METHODS (ANATOMY AND PALPATION) AND ULTRASONOGRAPHY IN EARLY BREAST-CANCER POSTOPERATIVE EXTERNAL IRRADIATION

Purpose: To evaluate the accuracy of three methods, anatomy (A), palpa tion (P) and ultrasounds (US) in localizing the clinical target volume (CTV) in patients (pts) with early breast cancer (EBC) undergoing bre ast external irradiation as part of conservation therapy. Material and methods: One hundred consecutive pts with EBC (T-is 1%, T-1 78%, T-2 21%, N- 68%, N+ 32%), treated with conservation surgery and breast irr adiation with opposed tangential portals, were prospectively analyzed. Anatomically, palpatory or ultrasound defined field borders for CTV l ocalizations were determined in the same position thanks to the utiliz ation of a vacuum-formed cellulose acetate immobilization cast, remove d during CTV definitions. Results: P and US CTV localizations have bee n found to coincide on the four margins (superior, inferior, medial, l ateral) in only 1/100 pts, while no pt showed identical A and US CTV l ocalizations. Only 31/397 (8%) field measurements with A, and 98/395 ( 25%) with P corresponded to US border definition. If mean and median v alues of each field border were considered, the CTV was generally over estimated with P appearing more accurate than A in a gross definition of the target (P < 0.01). However, a geographical miss of at least one field border of CTV occurred in 55% of pts with A and in 36% of pts w ith P. The most critical margin to be defined with conventional method s was the superior one: an underestimation of the cranial border of CT V with A was observed in 51% and with P in 22% of pts (22% and 8%, res pectively, when an underestimation by more than 1.5 cm was considered) . When pre-menopausal and peri/post-menopausal groups of pts were sepa rately analyzed, conventional methods were highly inaccurate to define the superior border in younger pts, in which a geographical miss was noted with A in 62% and with P in 35% of cases (P < 0.05). When an und erestimation of more than 1.5 cm was evaluated, these values were redu ced to 33% and 12%, respectively (P = 0.02). Also, in the subgroup of pre-menopausal patients the CTV defined by palpatory reference lines a ppeared to be more accurate than A-method (P < 0.01). Conclusions: Con ventional methods frequently appear inadequate to localize residual ma mmary gland in EBC post-operative external irradiation. This analysis evidentiates the inaccuracy of empirical CTV definition, and suggests that palpation or anatomical reference borders should be critically us ed and that state of art imaging methods should be included in treatme nt planning, particularly in premenopausal pts. If economical or indiv idual variables have to be taken into account, palpation might be cons idered in post-menopausal women. (C) 1997 Elsevier Science Ireland Ltd .