VALIDATION OF THERAPEUTIC RESPONSE ASSESSMENT BY BONE SCINTIGRAPHY IN PATIENTS WITH BONE-ONLY METASTATIC BREAST CANCERS DURING ZOLEDRONIC ACID TREATMENT: COMPARISON WITH COMPUTED TOMOGRAPHY ASSESSMENT

Abstract

Purpose: To validate the use of bone scintigraphy (BS) versus computed tomography (CT) for therapeutic monitoring in patients during treatment with zoledronic acid.

Materials and methods: Eleven patients with bone-only metastatic disease and being treated with zoledronic acid were included. The effects of therapies including chemotherapy and hormone therapy were evaluated in 25 separate examinations in total as follows: complete response (CR), when no bone metastasis was visible; partial response (PR), when a decrease in the lesion area was detected; stable disease (SD), when no or slight change was observed; and progressive disease (PD), when new or enlarged lesion areas were observed.

Results: The accuracies of examination by Readers 1, 2, and 3 respectively were 76%, 80% and 76% for BS, 52%, 48%, and 40% for CT, and 64%, 52% and 60% for BS and CT combined with Readers 2 and 3 observing significant differences between CT and BS results. The rates of interobserver agreement between Readers 1 and 2, between Readers 1 and 3, and between Reader 2 and 3 respectively, were 84%, 80% and 88% (κ = 0.648, 0.561 and 0.766) for BS, 52%, 56%, and 60% (κ = 0.180, 0.278 and 0.282) for CT, and 52%, 60%, and 56% (κ = 0.215, 0.282 and 0.232) for CT and BS combined.

Conclusion: BS is effective for assessing the response of bone metastasis to therapy in patients during zoledronic acid treatment.

Fig. 1.

Tumor marker evaluation vs. readers’ bone scintigraphy evaluation Assessments of serum tumor markers indicated 45 cases as PD while the readers judged 43 (96%) as PD and 2 as SD by bone scintigraphy. However, out of the 21 PR indicated by tumor marker levels, the readers judged 8 as either PD or SD (38%). PD indicates progressive disease, SD stable disease, PR partial response, N number, and TM tumor markers

Fig. 2.

A 69-year old female with breast cancer and bone metastases treated with zoledronic acid. Figs. 2A and D, B and E, C and F were taken on the same day. A. BS shows multiple abnormal uptakes consistent with bone metastases. B. BS obtained about 1 year after taking Fig. 2A shows new hot spots in the right humerus and more extended accumulation in the left femur, right iliac bone. Three readers judged the tumor response as PD. However the carcinoembryonic antigen level decreased from 46.5, which was measured when Fig. 2A was taken, to 29.7. Uptake of the left mandible was diagnosed as osteonecrosis. C. BS obtained about 1 year after taking Fig2. B shows new uptakes in the left ribs and more extended accumulation in the right humerus, left sternum head, and bilateral femur. All three readers judged the tumor response as PD. Carcinoembryonic antigen increased from 29.7, which was measured when Fig. 2B was taken, to 60.7. D. CT of Th11 vertebra obtained on the same day that Fig. 2A was taken shows blastic bone metastases. E. CT obtained 1 year after taking Fig. 2D (taken on the same day as Fig. 2B) shows an enlargement of sclerotic lesions to the right side of the vertebral body and arch. Although carcinoembryonic antigen decreased during the period between when Fig. 2D was taken and 2E was taken, the readers judged it as SD or PD. F. CT obtained 1 year after taking Fig. 2E (taken on the same day as Fig. 2C) shows a slight enlargement and strengthening of sclerotic lesions. Carcinoembryonic antigen elevated during the period between when Fig. 2E was taken and 2F was taken, and the readers judged it as SD or PD.