THE VALUE OF COMPUTED TOMOGRAPHIC MEASUREMENTS IN OSTEOSARCOMA AS A PREDICTOR OF RESPONSE TO ADJUVANT CHEMOTHERAPY

The response to pre-operative adjuvant chemotherapy was assessed with computed tomography (CT) in 41 osteosarcomas of the long bones of the lower limb. Measurements were made of cross-sectional tumour areas and volumes on both the pre- and post-chemotherapy CT examinations. Chang es in these measurements were compared with the percentage necrosis de termined from examination of the tumour histology from the excised spe cimen in 39 cases. An increase in the relative size of the tumour (exp ressed as a ratio of the pretreatment volume) showed a statistically s ignificant correlation with a poor tumour response as judged by the de gree of tumour necrosis. Further analysis of the results showed that q uantitative assessment of tumour response by CT is able to identify ca ses with poor response to therapy (negative predictive value=0.9). Thi s is, however, only achieved with a low specificity (0.5-0.6). These f indings are in agreement with other studies of tumour volume changes u sing MR imaging.