Rectal Cancer Medication

Updated: Jan 30, 2018
  • Author: Burt Cagir, MD, FACS; Chief Editor: N Joseph Espat, MD, MS, FACS  more...
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Medication

Medication Summary

The goals of pharmacotherapy are to down-stage the tumor, induce remission, reduce morbidity, and prevent complications.

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Antineoplastic agents

Class Summary

The recommendations from National Comprehensive Cancer Network 13th Annual Conference are outlined as follows. The use of as many chemotherapy drugs as possible is recommended to maximize the effect of adjuvant therapies for colon and rectal cancer. Bevacizumab in combination with chemotherapy is indicated in patients with positive or negative resectable synchronous metastases. For colon and rectal cancer, bevacizumab in combination with chemotherapy is also indicated in patients with unresectable synchronous metastases. FOLFOX —a combination of folinic acid, fluorouracil, and oxaliplatin — is reasonable to use for high-risk or intermediate-risk stage II patients (see Table 5).

FOLFOX is not indicated for good-risk or average-risk stage II patients. In patients in whom 5-fluorouracil treatment has failed, capecitabine should be avoided. Patients who experience no benefit from bevacizumab regimens should avoid continuing the therapy. Cetuximab should not be replaced with panitumumab. Patients with KRAS mutations should not be treated with cetuximab or panitumumab, as these mutations confer resistance to epidermal growth factor receptor (EGFR) inhibitors.

Fluorouracil (5-FU, Fluorouracil, Adrucil)

Blocks methylation of deoxyuridylic acid to thymidylic acid, thereby interfering with DNA synthesis. Dose is body-weight dependent and varies with specific protocol in which patient is involved.

Vincristine (Vincasar PFS, Oncovin)

Mechanism of action uncertain. May involve decrease in reticuloendothelial cell function or increase in platelet production. It is mitotic spindle inhibitor.

Leucovorin (Wellcovorin)

Potentiates effects of fluorouracil. Reduced form of folic acid that does not require enzymatic reduction reaction for activation. Allows for purine and pyrimidine synthesis, both of which are needed for normal erythropoiesis.

Given just prior to fluorouracil.

Irinotecan (Camptosar, Camptothecin-11, CPT-11)

Inhibits topoisomerase I, inhibiting DNA replication and, consequently, cell proliferation.

Oxaliplatin (Eloxatin)

A platinum-based antineoplastic agent used in combination with an infusion of 5-fluorouracil (5-FU) and leucovorin for the treatment of metastatic colorectal cancer in patients with recurrence or progression following initial treatment with irinotecan, 5-FU, and leucovorin. It forms interstrand and intrastrand Pt-DNA crosslinks that inhibit DNA replication and transcription. The cytotoxicity is cell-cycle nonspecific.

Cetuximab (Erbitux)

Recombinant human/mouse chimeric monoclonal antibody that specifically binds to the extracellular domain of human epidermal growth factor receptors (EGFR, HER1, c-ErbB-1). Cetuximab-bound EGF receptor inhibits activation of receptor-associated kinases, resulting in inhibition of cell growth, induction of apoptosis, and decreased production of matrix metalloproteinase and vascular endothelial growth factor. Indicated for treating irinotecan-refractory, EGFR-expressed, metastatic colorectal carcinoma. Treatment is preferably combined with irinotecan. May be administered as monotherapy if irinotecan is not tolerated.

Bevacizumab (Avastin)

Indicated as a first-line treatment for metastatic colorectal cancer. Murine-derived monoclonal antibody that inhibits angiogenesis by targeting and inhibiting vascular endothelial growth factor (VEGF). Inhibiting new blood vessel formation denies blood, oxygen, and other nutrients needed for tumor growth. Used in combination with standard chemotherapy.

Panitumumab (Vectibix)

Recombinant human IgG2 kappa monoclonal antibody that binds to human epidermal growth factor receptor (EGFR). Indicated to treat colorectal cancer that has metastasized following standard chemotherapy.

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Vaccine

Class Summary

HPV is associated with about 90% of anal cancer. In a study of homosexual males, HPV vaccine was shown to be 78% effective in prevention of HPV 16- and 18-related anal intraepithelial neoplasms. A study by Nielsen et al examined trends in incidence of anal cancer and high-grade anal intraepithelial neoplasia in Denmark from 1978-2008 and found that HPV vaccines may be a vital factor in the prevention of anal cancer and its precursor lesions. [92]

Papillomavirus vaccine, quadrivalent (Gardasil)

Quadrivalent human papillomavirus (HPV) recombinant vaccine. Vaccine efficacy mediated by humoral immune responses following immunization series. Indicated for prevention of anal cancer and associated precancerous lesions caused by HPV types 6, 11, 16, and 18 people aged 9-26 years.

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