Textbook of Medical-Surgical Nursing 3e

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Unit 3   Applying concepts from the nursing process

A few centres are using intra-operative radiation therapy (IORT), which involves delivering a single dose of high-fraction radiation therapy to the exposed tumour bed while the body cavity is open during surgery. Cancers for which IORT is being used include gastric, pancreatic, colorectal, bladder, and cervical cancers and sarcomas. Toxicity with IORT is mini- mised because the radiation is precisely targeted to the diseased areas, and exposure to overlying skin and structures is avoided. Internal radiation Internal radiation implantation, or brachytherapy , delivers a high dose of radiation to a localised area. The specific radio- isotope for implantation is selected on the basis of its half-life, which is the time it takes for half of its radioactivity to decay. This internal radiation can be implanted by means of needles, seeds, beads or catheters into body cavities (vagina, abdomen, pleura) or interstitial compartments (breast, prostate). Patients may have many fears or concerns about internal radiation and the nurse must be prepared to explain the various approaches and safety precautions that will be used to protect both the patient and the staff. Brachytherapy may be delivered as a temporary or a per- manent implant. Temporary applications may be delivered as high-dose radiation (HDR) for short periods of time or low - dose radiation (LDR) for a more extended period of time. The primary advantage of HDR sources of brachy­therapy is that treatment time is shorter, there is reduced exposure to personnel and the procedure can typically be performed as an outpatient procedure over several days. HDR brachytherapy can be used for intraluminal, inter­stitial, intracavitary and surface lesions. Intraluminal brachytherapy involves the insertion of catheters or hollow tubes into the lumens of organs so that the radioisotope can be delivered as close to the tumour bed as possible. Obstructive lesions in the bronchus, oesophagus or bile duct can be treated with this approach. Contact or surface application is used for treatment of tumours of the eye such as retinoblastoma in children or ocular melanoma in adults. Intracavitary radioisotopes are frequently used to treat gynae- cological cancers. In these malignancies, the radioisotopes are inserted into specially positioned applicators after the position is verified by x-ray. These radioisotopes remain in place for a prescribed period and then are removed. Patients are main- tained on bed rest and log-rolled to prevent displacement of the intracavitary delivery device. An indwelling urinary catheter is inserted to ensure that the bladder remains empty. Low-residue diets and antidiarrhoeal agents, such as diphen­ oxylate (Lomotil), are provided to prevent bowel movement during therapy and to prevent the radioisotopes from being displaced. Interstitial implants, used in treating such malignancies as prostate, pancreatic or breast cancer, may be temporary or per- manent, depending on the radioisotopes used. These implants usually consist of seeds, needles, wires or small catheters positioned to provide a local radiation source and are less fre- quently dislodged. With internal radiation therapy, the farther the tissue is from the radiation source, the lower the dosage. This spares the non-cancerous tissue from the radiation dose. Prostate seed therapy is probably the most frequently used type of interstitial brachytherapy, where small radio­active seeds are placed directly into the prostate gland under ultrasound guidance. These seeds are permanently placed and appropriate

safety precautions must be employed for several days due to the risk of radiation exposure to others. Recently, partial breast irradiation utilising a technique for interstitial isotope employing the MammoSite™ device has shown benefit in certain localised breast cancers. MammoSite™ involves the placement of an inflatable balloon within the cavity created after surgical resection of the breast tumour. HDR brachy­ therapy fractions are delivered via a radioactive seed inserted into the balloon over the course of 5 days. Studies have shown comparable 5-year outcomes for selected patients, with minimal toxicities and excellent cosmesis, when compared with outcomes with whole breast EBRT for postlumpectomy patients. The advantages for patients are reduced treatment time (5 days versus 6 to 8 weeks), less radiation exposure to healthy tissues and adjacent organs (heart and lungs), less skin reaction, and improved cosmesis of the breast. Nursing care for these patients must include instruction in rigorous catheter care and wound management, as the patient is treated as an outpatient with a double-lumen catheter projecting from the breast (Benitez et al., 2007). Systemic brachytherapy involves the IV administration of a therapeutic radioactive isotope targeted to a specific tumour. Radioactive iodine (I131) is a widely used form of systemic brachytherapy and is the primary treatment for thyroid cancer. Strontium 89 is utilised for bone metastases, samarium 153 is used for metastatic bone lesions and phosphorus 32 is used for treatment of malignant ascites associated with ovarian cancer. Radioisotopes are now also being used as radio-immunotherapy for the treatment of refractory non-Hodgkin lymphoma (NHL). Radio-immunotherapy involves the administration of a radio- nuclide that is chemically conjugated (bound) to a mono­clonal antibody (discussed later in this chapter) that specifically targets NHL tumour cells, delivering the radionuclide directly to the tumour and sparing the surrounding healthy tissue. There are currently two radio-immunotherapy agents available for treatment of NHL: ibritumomab tiuxetan (Zevalin), which utilises yttrium 90 as the radioactive beta-emitting nucleotide and iodine 131 tositumomab (Bexxar), which utilises I131 as the beta- and gamma-emitting radionuclide. Toxicity Toxicity of radiation therapy is localised to the region being irradiated. Toxicity may be increased when concomitant chemotherapy is administered. Acute local reactions occur when normal cells in the treatment area are also destroyed and cellular death exceeds cellular regeneration. Body tissues most affected are those that normally proliferate rapidly, such as the skin, the epithelial lining of the gastrointestinal tract, including the oral cavity, and the bone marrow. Altered skin integrity is a common effect and can include alopecia (hair loss), erythema and shedding of skin (desquamation). Skin reactions are identified and graded by severity along a con­ tinuum ranging from erythema and dry desquamation, to moist desquamation (dermis exposed, skin oozing serous fluid), and, potentially, ulceration. After treatments have been completed, reepithelialisation occurs (McQuestion, 2006). Alterations in oral mucosa secondary to radiation therapy include stomatitis (inflammation of the oral tissues), xero- stomia (dryness of the mouth), change and loss of taste, and decreased salivation. The entire gastrointestinal mucosa may be involved, and oesophageal irritation with chest pain and dysphagia may result. Anorexia, nausea, vomiting and