CHOP is the acronym for a chemotherapy regimen used in the treatment of non-Hodgkin lymphoma. CHOP consists of: Cyclophosphamide, an alkylating agent which damages DNA by binding to it and causing the formation of cross-links (also called doxorubicin or adriamycin), an intercalating agent which damages DNA by inserting itself between DNA bases (vincristine), which prevents cells from duplicating by binding to the protein tubulin or , which are corticosteroids. Sometimes the chimeric anti-CD20 monoclonal antibody, rituximab, is added to this treatment regimen to form the R-CHOP regimen. Dosing regimen R-Maxi-CHOP is used in mantle cell lymphoma and is given in 21-day intervals, alternating with R-HDAC (rituximab + high-dose cytarabine). In most other non-Hodgkin lymphomas (excluding some aggressive forms), standard-dose [R]-CHOP is generally used as first-line therapy. Uses and indications Normal cells are more able than cancer cells to repair damage from chemotherapy drugs. This regimen can also be combined with the monoclonal antibody rituximab if the lymphoma is of B cell origin; this combination is called R-CHOP. Typically, courses are administered at an interval of two or three weeks (CHOP-14 and CHOP-21 respectively). A staging CT scan is generally performed after three cycles to assess whether the disease is responding to treatment. In patients with a history of cardiovascular disease, doxorubicin (which is cardiotoxic) is often deemed to be too great a risk and is omitted from the regimen. The combination is then referred to as COP (cyclophosphamide, Oncovin, and prednisone or prednisolone) or CVP (cyclophosphamide, vincristine, and prednisone or prednisolone). Side-effects and complications The combination is generally well tolerated. Chemotherapy-induced nausea and vomiting may require antiemetics (such as ondansetron), and hemorrhagic cystitis is prevented with administration of mesna. Alopecia (hair loss) is common. Neutropenia generally develops in the second week. During this period, many clinicians recommend pegfilgrastim or prophylactic use of ciprofloxacin. If a fever develops in the neutropenic period, urgent medical assessment is required for neutropenic sepsis, as infections in patients with low neutrophil counts may progress rapidly. Allopurinol is typically co-administered prophylactically to prevent hyperuricemia that results from tumor lysis syndrome, the result of rapid death of tumor cells. History A pivotal study published in 1993 compared CHOP to several other chemotherapy regimens (e.g. m-BACOD, ProMACE-CytaBOM, MACOP-B) for advanced non-Hodgkin's lymphoma. CHOP emerged as the regimen with the least toxicity but similar efficacy. However, in Germany in 2012, bendamustine has displaced [R-]CHOP to become the first line