Rectal Cancer (cont.)
What Are Medical Treatments for Rectal Cancer?
Surgery is likely to be the only necessary step in treatment if stage I rectal cancer is diagnosed.
The risk of the cancer coming back after surgery is low, and therefore, chemotherapy is not usually offered. Sometimes, after the removal of a tumor, the doctor discovers that the tumor penetrated into the mesorectum (stage II) or that the lymph nodes contained cancer cells (stage III). In these individuals, chemotherapy and radiation therapy are offered after recovery from the surgery to reduce the chance of the cancer returning. Chemotherapy and radiation therapy given after surgery is called adjuvant therapy.
If the initial exams and tests show a person to have stage II or III rectal cancer, then chemotherapy and radiation therapy should be considered before surgery. Chemotherapy and radiation given before surgery is called neoadjuvant therapy. This therapy lasts approximately six weeks. Neoadjuvant therapy is performed to shrink the tumor so it can be more completely removed by surgery. In addition, a person is likely to tolerate the side effects of combined chemotherapy and radiation therapy better if this therapy is administered before surgery rather than afterward. After recovery from the surgery, a person who has undergone neoadjuvant therapy should meet with the oncologist to discuss the need for more chemotherapy. If the rectal cancer is metastatic, then surgery and radiation therapy would only be performed if persistent bleeding or bowel obstruction from the rectal mass exist. Otherwise, chemotherapy alone is the standard treatment of metastatic rectal cancer. At this time, metastatic rectal cancer is not curable. However, average survival times for people with metastatic rectal cancer have lengthened over the past several years because of the introduction of new medications.
What Medications Treat Rectal Cancer?
The following chemotherapy drugs may be used at various points during therapy:
- 5-Fluorouracil (5-FU): This drug is given intravenously either as a continuous infusion using a medication pump or as quick injections on a routine schedule. This drug has direct effects on the cancer cells and is often used in combination with radiation therapy because it makes cancer cells more sensitive to the effects of radiation. Side effects include fatigue, diarrhea, mouth sores, and hand, foot, and mouth syndrome (redness, peeling, and pain in the palms of the hands and the soles of the feet).
- Capecitabine (Xeloda): This drug is given orally and is converted by the body to a compound similar to 5-FU. Capecitabine has similar effects on cancer cells as 5-FU and can be used either alone or in combination with radiation therapy. Side effects are similar to intravenous 5-FU.
- Leucovorin (Wellcovorin): This drug increases the effects of 5-FU and is usually administered just prior to 5-FU administration.
- Oxaliplatin (Eloxatin): This drug is given intravenously once every two or three weeks. Oxaliplatin has recently become the most common drug to use in combination with 5-FU for the treatment of metastatic rectal cancer. Side effects include fatigue, nausea, increased risk of infection, anemia, and peripheral neuropathy (tingling or numbness of the fingers and toes). This drug may also cause a temporary sensitivity to cold temperatures up to two days after administration. Inhaling cold air or drinking cold liquids should be avoided if possible after receiving oxaliplatin.
- Irinotecan (Camptosar, CPT-11): This drug is given intravenously once every one to two weeks. Irinotecan is also commonly combined with 5-FU. Side effects include fatigue, diarrhea, increased risk of infection, and anemia. Because both irinotecan and 5-FU cause diarrhea, this symptom can be severe and should be reported immediately to a doctor.
- Bevacizumab (Avastin): This drug is given intravenously once every two to three weeks. Bevacizumab is an antibody to vascular endothelial growth factor (VEGF) and is given to reduce blood flow to the cancer. Bevacizumab is used in combination with 5-FU and irinotecan or oxaliplatin for the treatment of metastatic rectal cancer. Side effects include high blood pressure, nose bleeding, blood clots, and bowel perforation.
- Cetuximab (Erbitux): This drug is given intravenously once every week. Cetuximab is an antibody to epidermal growth factor receptor (EGFR) and is given because rectal cancer has large amounts of EGFR on the cell surface. Cetuximab is used alone or in combination with irinotecan for the treatment of metastatic rectal cancer. Side effects include an allergic reaction to the medication and an acne-like rash on the skin. Clinical trials are underway to evaluate this antibody for the treatment of localized rectal cancer.
- Vincristine (Vincasar PFS, Oncovin): The mechanism of action of this drug is not fully known; is known to inhibit cell division.
- Panitumumab (Vectibix): This recombinant monoclonal antibody binds to human epidermal growth factor receptor (EGFR) and is used to treat colorectal cancer that has metastasized after chemotherapy treatment.
Medications are available to alleviate the side effects of chemotherapy and antibody treatments. If side effects occur, an oncologist should be notified so that they can be addressed promptly.
Home remedies do not treat rectal cancers, but some may help a patient manage side effects of the disease and treatment. For example, ginger tea may help reduce nausea and vomiting while salty crackers and sips of water may reduce diarrhea. However, patients are urged to discuss any home remedies with their doctors before using them.
Medically Reviewed by a Doctor on 9/11/2017
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