Tumor 5-fluorouracil treatment

Uracil is used more effectively, in nucleic acid synthesis within a rat hepatoma than in normal liver. This observation appears to have stimulated the synthesis of 5-fluorouracil (1027) as an antimetabolite mainly because the introduction of a fluorine atom involves a minimal increase in size. In the event, 5-fluorouracil did prove to have antineoplastic activity and it is now a valuable drug for treatment of tumors of the breast, colon or rectum, and to a lesser extent, gastric, hepatic, pancreatic, uterine, ovarian and bladder carcinomas. As with other drugs which interfere with DNA synthesis, the therapeutic index is quite low and great care is required during treatment (69MI21301). 

One commonly used agent is the antimetabolite 5-fluorouracil (5-FU), which is frequently used as an adjuvant therapy in conjunction with surgical excision in the treatment of solid tumors. p53 can directly trigger apoptosis in cells exposed to 5-FU in vitro [1]. In addition, there is a substantial amount of clinical... 

Fluorouracil (5-FU) is an antineoplastic agent that usually arrests tumor cells at the Gl-S phase of the cell cycle and the choice in the treatment of carcinoma of colon or rectum it is also used in the treatment of precancerous dermatoses, especially actinic keratosis for which... 

Gastrointestinal Tumor Study Group. Radiation therapy and fluorouracil with or without semustine for the treatment of patients with surgical adjuvant adenocarcinoma of the rectum. J Clin Oncol 1992 10 549-557. 

Cyclophosphamide is a component of CMF (cyclophosphamide, methotrexate, 5-fluorouracil) and other drug combinations used in the treatment of breast cancer. Cyclophosphamide in combination may produce complete remissions in some patients with ovarian cancer and oat cell (small cell) lung cancer. Other tumors in which benehcial results have been reported include non-oat cell lung cancers, various sarcomas, neuroblastoma, and carcinomas of the testes, cervix, and bladder. Cyclophosphamide also can be employed as an alternative to azathioprine in suppressing immunological rejection of transplant organs. 

Fluorouracil is used in several combination regimens in the treatment of breast cancer. It also has palliative activity in gastrointestinal adenocarcinomas, including those originating in the stomach, pancreas, liver, colon, and rectum. Other tumors in which some antitumor effects have been reported include carcinomas of the ovary, cervix, oropharynx, bladder, and prostate. Topical 5-fluorouracil cream has been useful in the treatment of premalignant keratoses of the skin and superficial basal cell carcinomas, but it should not be used in invasive skin cancer. 

Dotor E, Cuatreeases M, Martinez-Iniesta M et al. Tumor thymidylate synthase 1494del6 genotype as a prognostie faetor in eoloreetal eancer patients receiving fluorouracil-based adjuvant treatment. J Clin Oncol 2006 24 1603-1611. 

Although the endometrial cancers associated with tamoxifen are usually pure adenocarcinomas, other types of rare tumors have also been reported. A pure uterine rhabdomyosarcoma has been reported (99), and a mesodermal mixed tumor of the endometrium occurred 5 years after 5 years of tamoxifen therapy (100). The tumor responded only to combined treatment with doxorubicin, cyclophosphamide, 5-fluorouracil, and carbopla-tin. It is possible that this type of tumor arises later than adenocarcinomas and should be looked for during longterm use of tamoxifen. 

Fluorouracil is the most widely used agent for the treatment of colorectal cancer, both as adjuvant therapy as well as for advanced disease. In addition, it has activity against a wide variety of solid tumors, including cancers of the breast, stomach, pancreas, esophagus, liver, head and neck, and anus. Its major toxicities are listed in Table 55-3. 

Drugs used in cancer chemotherapy are cytotoxic drugs, hormones, plant derivatives, radioactive isotopes, and miscellaneous agents (e.g., procarbazine, hydroxyurea, mitotane). The plant-based drugs vincristine, vinblastine, vinorel-bine, etoposide, and campothecins. Radioactive isotopes, such as 131 iodine (131 I), are used in the treatment of thyroid tumors. Cytotoxic drugs (e.g., cis-platin, cyclophosphamide, 6-mercaptopurine, 5-fluorouracil, and methotrexate are used for the treatment of cancer. 

Further studies have validated this hypothesis, in part,4 and ultimately this inventive premise was borne out in clinical practice. As a result, 5-FU (5) was eventually approved for treatment of solid tumors, such as breast, colorectal, and gastric cancers. Marketed as Adrucil when administered intravenously, 5-FU can be used either as monotherapy or combination therapy with various cytotoxic drugs and biochemical modulators, such as leucovorin and methotrexate.5 Because 5-fluorouracil is not orally bioavailable, it must be administered by continuous infusion to optimize its efficacy due to its short half-life in plasma. In addition, 5-FU has poor selectivity toward tumors in vivo, and its distribution into tissues such as bone marrow, the gastrointestinal tract, the liver and skin causes high incidences of toxicity. In addition, in spite of its limited lipid solubility, 5-fluorouracil diffuses readily across the blood-brain barrier into cerebrospinal fluid and brain tissue.1,5... 

In summary, capecitabine (1), an A -carbamate pyrimidine nucleoside prodrug of cytotoxic antimetabolite 5-fluorouracil, is an FDA-approved anticancer drug that can be administered orally. This compound uses a multilayer of prodrug strategies that not only avoids side effects arising from exposure of toxic metabolites to healthy tissue but is converted to 5-fluorouracil only by enzymes preferentially expressed in many cancer cell types, thus resulting in selective delivery of the drug to tumors. Capecitabine is marketed under the trade name of Xeloda for use in the treatment of metastatic colorectal and breast cancers and metastatic breast cancer that is resistant to paclitaxel or anthracycline therapies. 

The most advanced products based on the implantable gel technology include the Intradose (cisplatin/ epinephrine) injectable gel for treatment of solid tumors and the Advasite (fluorouracil/epinephrine)... 

A large number of compounds in category 3 act at different sites in the pathways for purine and pyrimidine biosynthesis. These compounds are very toxic for rapidly growing tumors and bacteria, making them useful in cancer chemotherapy and treatment of bacterial infections. 6-Mercaptopurine is a potent inhibitor of purine biosynthesis, and 5-fluorouracil inhibits thymidylate synthesis. Some compounds, such as hydroxyurea and sulfonamides, inhibit the synthesis of both purine and pyrimidine nucleotides. These are only a few of the many compounds useful in treating cancer and infectious diseases (see Chapter 10). 

Therapeutic applications Fluorouracil is employed primarily in the treatment of slowly growing, solid tumors (for example, colorectal, breast, ovarian, pancreatic, and gastric carcinomas). Adjuvant therapy with levamisole, a veterinary anthelmintic agent, improves the survival of patients with colonic cancer. 5-FU is also effective for the treatment of superficial basal cell carcinom when applied topically. 

Fluorouracil (5-FU), a pyrimidine analog, has been clinically used as a popular antitumor agent for the treatment of various malignant tumors such as head and neck [22], gastric [23], esophageal [24], ovarian [25] and lung can-... 

Squalamine has been tested in mammary, ovary, and lung cancer xenograft mouse models [20,23-26]. Results sho ved that squalamine alone had a modest effect on tumor growth delay and in some cases it resulted in decreased number of lung metastases. However, in most studies, squalamine treatment was more efficacious when combined with previously established anticancer agents such as cyclophosphamide, cisplatin, carboplatin, paclitaxel, 5-fluorouracil, or genestein, or with radiation therapy. 

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