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Cytotoxic drugs, hormones, antihormones, and biologic agents have become increasingly effective means of cancer chemotherapy. Many patients are treated on protocols to provide optimal therapy for refractory or poorly responsive malignancies. Treatment may be inadequate or ineffective because of drug resistance of the tumor cells. This has been attributed to spontaneous genetic mutations.
Molecular mechanisms of drug resistance to chemotherapy are now the subject of intense study. In many instances, specific drug resistance results from an amplification in the number of gene copies for an enzyme inhibited by a specific chemotherapeutic agent. A more general form of "multidrug resistance" (MDR) has been described in association with expression of a gene (MDR1) encoding a transmembrane glycoprotein of MW 170 (P-glycoprotein) on tumor cells. This protein is an energy-dependent transport pump that facilitates drug efflux from tumor cells and promotes resistance to a broad spectrum of unrelated cancer drugs. Acquired multidrug resistance in multiple myeloma and lymphoma. Unfortunately, the doses of verapamil required to. The use of cyclosporine to enhance the effect of etoposide in purging resistant tumor cells in vitro from autologous bone marrow is under investigation. Cyclosporine has also been shown to enhance the cytotoxic effect of multiagent chemotherapy against resistant multiple myeloma. Verapamil and cyclosporine increase the accumulation and cytotoxicity of daunorubicin in myeloid leukemia cells, enhancing cell kill. MDR modulators.
High-dose chemotherapy followed by bone marrow transplantation is curative therapy for various types of leukemia, multiple myeloma, and high-risk lymphoma and testicular cancer. Allogeneic or autologous bone marrow or peripheral blood stem cells with or without ex vivo purging is used depending on the disease. The use of growth factors and blood stem cells has decreased the toxicity and cost of bone marrow transplantation. Autologous transplantation may now be used with low morbidity and mortality on selected patients up to age 70. In addition, dose-intense chemotherapy regimens with autologous bone marrow or peripheral blood.
While most anticancer drugs are used systemically, there are selected indications for local or regional administration. Regional administration involves direct infusion of active chemotherapeutic agents into the tumor site (eg, intravesical therapy, intraperitoneal therapy, hepatic artery infusion with or without embolization of the main blood supply of the tumor).
A summary of the types of cancer responsive to chemotherapy and the current treatments of choice is offered in Table 4B3. In some instances (eg, Hodgkin's disease), optimal therapy may require a combination of therapeutic resources, eg, radiation plus chemotherapy rather than either modality alone. Patients with stages I, II, and IIIA Hodgkin's disease are often treated with radiation alone, avoiding the potential toxicity of systemic chemotherapy. A small percentage of these patients may require chemotherapy later..
Treatment choices for cancers responsive to systemic agents.
Diagnosis Current Chemotherapy of Choice and Procedures
Acute lymphocytic leukemia Induction: Combination chemotherapy. Adults: Doxorubicin, cytarabine,
Vincristine, prednisone, daunorubicin, and asparaginase. cyclophosphamide, etoposide, teniposide (VM-26),1
Children: Vincristine, prednisone with or without allopurinol,2 autologous bone marrow transplantation
asparaginase.
Consolidation: Multiagent alternating chemotherapy.
Allogeneic bone marrow transplant for young adults or high-risk disease or second remission. CNS prophylaxis
with intrathecal methotrexate with or without whole brain radiation.
Remission maintenance: Methotrexate, thioguanine.
Acute myelocytic and Induction: Combination chemotherapy with cytarabine Mitoxantrone, idarubicin, etoposide,
myelomonocytic and an anthracycline (daunorubicin, idarubicin). mercaptopurine, thioguanine,
leukemia Tretinoin for acute promyelocytic leukemia. azacitidine,1 amsacrine,1
Consolidation: High-dose cytarabine. Autologous methotrexate, doxorubicin, tretinoin,
(with or without purging) or allogeneic bone marrow allopurinol,2 leukapheresis, prednisone
transplantation for high-risk disease or second remission.
Chronic myelocytic Hydroxyurea, alpha interferon. Allogeneic bone marrow Busulfan, mercaptopurine,
leukemia transplantation for young patients. thioguanine, cytarabine, plicamycin, melphalan,
autologous bone marrow transplantation, allopurinol.
Chronic lymphocytic Chlorambucil and prednisone or fludarabine (if treatment Vincristine, cyclophosphamide, doxorubicin,
leukemia is indicated). Cladribine (2-chlorodeoxyadenosine; CdA),
androgens,2 allopurinol2
Hairy cell leukemia Cladribine (2-chlorodeoxyadenosine; CdA). Pentostatin (deoxycoformycin), alpha interferon
Hodgkin=s disease Combination chemotherapy: doxorubicin (Adriamycin), Carmustine, lomustine, etoposide,
(stages III and IV) bleomycin, vinblastine, dacarbazine (ABVD) or thiotepa, autologous bone marrow transplantation
mechlorethamine, vincristine, prednisone, procarbazine
(MOPP) or alternating MOPP/ABVD or MOPP/ABV,
autologous bone marrow transplant for high-risk patients
or relapsed disease.
Non-Hodgkin=s lymphoma Combination therapy depending on histologic classification Bleomycin, methotrexate, etoposide,
but usually including cyclophosphamide, vincristine, chlorambucil, fludarabine, lomustine, carmustine,
doxorubicin, and prednisone (CHOP) with or without cytarabine, thiotepa, amsacrine, mitoxantrone,
other agents. Autologous bone marrow transplantation in autologous or allogeneic bone marrow transplantation
high-risk first remission or first relapse.
Multiple myeloma Combination chemotherapy: melphalan and prednisone Etoposide, cytarabine, alpha interferon,
or melphalan, cyclophosphamide, carmustine, dexamethasone, autologous bone marrow
vincristine, doxorubicin, and prednisone. Autologous transplantation