Modulation of P-glycoprotein-mediated multidrug resistance in the CC531 rat colon tumor model

About half of the patients that come to the physician with cancer have a localized stage of the disease and can be cured by surgery or radiotherapy. The remaining cancers have spread systemically because the primary tumor has metastasized or because they are systemic cancers by nature. The only hope for cure for patients with these cancers lies in systemic treatment such as chemotherapy or immunotherapy. Cure can be obtained by intensive chemotherapy in childhood acute leukemia and sarcoma, in adult testicular cancer and choriocarcinoma, and, to a lesser extent, in lymphomas. In other malignancies like breast cancer adjuvant chemotherapy after curative surgical ablation has proven beneficial in a minority of the patients by reducing the likelihood of disease recurrence. In these patients residual microscopic disease, which would have resulted in disease recurrence, has been eradicated by chemotherapy. However, only 5%-10% of the patients with systemic cancer can be cured by chemotherapy to day.l,2 A still much smaller percentage of the cancers responds to various forms of immunotherapy.