99mTc-MIBI imaging as a predictor of therapy response in osteosarcoma compared with multidrug resistance-associated protein and P-glycoprotein expression.

UNLABELLED: In vitro studies have demonstrated that (99m)Tc-methoxyisobutylisonitrile ((99m)Tc-MIBI) is a transport substrate of multidrug resistance (MDR)-related proteins. The aim of this clinical study was to evaluate whether (99m)Tc-MIBI scintigraphy was a functional imaging tool for in vivo detection of multidrug resistance-associated protein (MRP) expression in osteosarcoma and to investigate the role of MRP and (99m)Tc-MIBI imaging to predict the clinical outcome. We also examined whether the scintigraphic parameters would help to distinguish the functional capacity of P-glycoprotein (Pgp) and MRP. METHODS: Twenty-four patients with a diagnosis of osteosarcoma were studied before neoadjuvant chemotherapy. Tumor-to-background ratios of both early (10 min) and delayed (1 h) images and the percentage washout rate (WR%) of (99m)Tc-MIBI were calculated. Immunohistochemical analysis of MRP and Pgp was performed on biopsy specimens, and the response to preoperative chemotherapy was assessed by histopathologic examination. RESULTS: Fifteen of 24 osteosarcoma samples in our series (62.5%) showed significant expression of MRP. The level of MRP expression was significantly correlated with the WR% of (99m)Tc-MIBI (r = 0.58, P = 0.003), and the WR% of (99m)Tc-MIBI was significantly faster in patients with high MRP expression than in those with a low MRP score (P = 0.007). The clearance rate of (99m)Tc-MIBI was significantly slower in tumor samples with negative or low expression of both Pgp and MRP (16% +/- 6.2%) when compared with osteosarcomas with high expression of both proteins (31.7% +/- 8.7%) (P = 0.001). There was not a significant difference between the WR% of (99m)Tc-MIBI in tumors with coexpression of both proteins and in tumors with high expression of either Pgp or MRP. Both the rate of MRP expression and the WR% of (99m)Tc-MIBI were significantly correlated with response rate. CONCLUSION: Our results suggest that the WR% of (99m)Tc-MIBI is correlated with MRP expression. Both the WR% of (99m)Tc-MIBI and MRP expression are correlated with therapy response. (99m)Tc-MIBI can be used as a general probe for functional imaging of both Pgp and MRP; however, it is not capable of differentiating the functional status of either MDR-related glycoprotein.

p53 and Ki-67 expression as prognostic factors in cystosarcoma phyllodes.

We have reviewed the histopathological, clinical outcome and immunohistochemical status in 21 women with cystosarcoma phyllodes (CSP) tumors of the breast. We assessed 12 tumors as histopathologically benign and 9 tumors as malignant. The median patient ages in benign and malignant CSP tumors were 39.6 and 45.4 years of age, respectively. The stromal cellularity, stromal cellular atypism, high mitotic activity, atypic mitoses, stromal overgrowth, infiltrative tumor contour, and heterologous stromal elements were significant features of the malignant CSP tumors. Benign CSP tumors were predominantly of fibroadenomatous architecture with cellular stroma (mild or moderate) and some distortion and elongation of glandular elements. Five malignant CSP tumors were stained positively with p53, and 6 malignant CSP tumors were stained immunohistochemically with Ki-67. All benign CSP tumors were negatively stained for p53 and Ki-67. The patients with benign CSP tumors were treated with local excision ( n=11) and with subcutaneous mastectomy ( n=1). Malignant CSP tumors were treated with wide local excision ( n=1), partial mastectomy ( n=1), simple mastectomy ( n=2), and modified radical mastectomy ( n=5). Two patients with a high mitotic rate and high values of p53 and Ki-67 received additional radiotherapy and chemotherapy. One case had liver metastasis. This tumor had high mitotic figures, stromal overgrowth, severe stromal cellularity, and 20% Ki-67 and mild p53 positivity. We suggest that p53 and Ki-67 can play an important role in predicting prognosis and yielding additional therapy besides conventional prognostic factors in the treatment of the CSP patients.