BACKGROUNDThe presence of residual tumor after surgery for pituitary adenoma may necessitate further treatment. The suprasellar and parasellar extension of the tumor have been widely considered as the predictors for residual tumor. However there is scarcity of studies regarding the preoperative tumor volume and residual tumor. This study was conducted to evaluate if tumor volume could predict the outcome of transsphenoidal pituitary surgery.

METHODSA prospective study was designed and 48 patients who underwent transsphenoidal pituitary surgery within 1 year in the First Affiliated Hospital of Xi'an Jiaotong University were included in this study. The preoperative tumor volume and immediate postoperative tumor volume (within 4 - 7 days) were calculated in the contrast magnetic resonance imaging by using the formula of ellipsoid. All these volumes were divided into three subgroups, i.e. group 1, group 2 and group 3 with preoperative volume of less than 4 cm(3), 4 - 8 cm(3), and more than 8 cm(3) respectively. The parasellar and suprasellar extension of the tumor were also classified by Knosp and modified Hardy's classifications.

RESULTSBaseline characteristics were comparable. The preoperative tumor volume of more than 8 cm(3) (group 3, (12.1 ± 1.1) cm(3)) had increased risk on postoperative tumor residue (P < 0.01) than the other two groups ((2.1 ± 0.3) cm(3) and (6.1 ± 0.3) cm(3) in groups 1 and 2). The mean postoperative volume in group 3 patients ((2.2 ± 0.1) cm(3)) was significantly higher than the other two groups (P < 0.01).

CONCLUSIONPreoperative volume of more than 8 cm(3) can be considered as a predictor for postoperative residual volume.