P-glycoprotein expression as a predictor of the outcome of therapy for neuroblastoma

Article Abstract:

Cancer cells may become resistant to the effects of chemotherapeutic drugs in a variety of ways. Usually, the development of resistance to one drug carries over to other drugs with the same general type of chemical structure. However, cancer cells can also develop multidrug resistance, in which drug resistance carries over to drugs with unrelated chemical structures. The physiological mechanism for this drug resistance appears to be an increase in the synthesis of cell protein known as P-glycoprotein. This protein apparently works as a pump to expel substances that do not belong in the cell and therefore ejects chemotherapeutic drugs. Researchers have now accumulated evidence suggesting that P-glycoprotein may be an important determinant of success or failure in the treatment of the childhood cancer neuroblastoma. The current study was performed retrospectively on the tumors of 67 children with neuroblastoma; immunological techniques were used to detect P-glycoprotein in the microscopic slides. Specimens taken prior to treatment had no detectable P-glycoprotein in the 23 patients with Stage I or Stage II disease. P-glycoprotein was detected in one of 17 patients with Stage III disease and in 12 of 19 patients with Stage IV disease. (P-glycoprotein could not be detected in the eight patients with Stage IVS disease, a special category of Stage IV in which the metastatic spread of disease is limited.) A total of 44 patients had more advanced Stage III, IVS, or IV disease. Among these patients, 26 of 31 patients who were negative for P-glycoprotein responded to chemotherapeutic treatment; 6 of 13 who were positive for P-glycoprotein responded to chemotherapy. (Consumer Summary produced by Reliance Medical Information, Inc.)

Research, Chemotherapy, Tumor proteins

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Expression of P-glycoprotein in high-grade osteosarcomas in relation to clinical outcome

Article Abstract:

High levels of P-glycoprotein in tumor cells of osteosarcoma appear to increase the risk of tumor relapse or death following surgery and chemotherapy. Osteosarcoma is a bone tumor that is often cancerous. Researchers studied the levels of the membrane pump P-glycoprotein in tumor cells of 92 patients with osteosarcoma who had surgery and chemotherapy. In 28 (30%) of the tumors, P-glycoprotein appeared at elevated levels in cells throughout the tumor. Tumors located at the end of bones closer to the torso tended to have higher P-glycoprotein levels. During a minimum follow-up of 63 months, the rate of tumor relapse or death during remission was 3.4 times higher in people with high P-glycoprotein levels. Poor response to chemotherapy also appeared to increase the likelihood of a poor outcome.

Osteosarcoma

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Predicting outcome in neuroblastoma

Article Abstract:

Research continues to show that the biologic characteristics of neuroblastoma determine its prognosis. This childhood tumor can go into spontaneous remission or metastasize to other organs and lead to death. Some children at low risk may only need surgery whereas those at high risk may need aggressive treatment including surgery and chemotherapy. A 1999 study showed that children with a chromosomal abnormality called gain of chromosome arm 17q have a much poorer prognosis than those who don't. This abnormality occurs when part of chromosome 17 becomes attached to another chromosome.

Health aspects, Editorial, Chromosome abnormalities

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