240
Unit 3
Applying concepts from the nursing process
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
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
