Radiation Oncology
Radiation oncology is the use of radiation to treat
cancer. Radiation can be used by itself, or in
conjunction with other modalities to fight cancer
such as chemotherapy and surgery. Through the use of
CT scans, a computer program is used to plan the
radiation therapy in a way to maximize destruction
of the tumor. VSNT uses a linear accelerator with a
multileaf collimater that is computer controlled to
direct and form the radiation beam in such a fashion
to put the radiation in the tumor and avoid
unaffected tissue. This does a lot to control side
effects associated with radiation therapy. Depending
on the type of tumor that is present, radiation may
be use to eliminate the cancer, shrink the tumor, or
provide pain relief for the patient. Radiation may
be administered in a number of different protocols
designed to accomplish the needs of the pet and pet
owners, while maintaining a good quality of life for
the patient. We have found that most patients
tolerate radiation therapy very well.
Injection
site sarcomas or vaccine associated sarcomas
are locally aggressive tumors that often recur
following surgical removal. The average time for
recurrence following surgical excision is 3 months.
When surgery and radiation therapy are combined to
treat this disease the median survival time is
extended to two years. This is a tumor in which
preoperative radiation therapy is considered
optimal. Please consult a veterinary radiation
oncologist to discuss further treatment options.
Mast
cell tumors are one of the most common skin
tumors in the dog. Wide surgical excision with 3 cm
margins is often curative for grade 1 and grade 2
mast cell tumors. If a wide surgical excision is not
possible radiation therapy is used to control this
tumor. Studies have shown that 88% of dogs treated
with a combination of surgery and radiation therapy
are disease-free at 5 years following treatment.
Meningiomas
are the most common brain tumor seen in
dogs. Treatment options consist of surgery,
radiation therapy, or a combination of the two. A
recent study has shown that the median survival time
for dogs with meningiomas treated with radiation
therapy is 20 months.
Nasal
tumors in the dog are often diagnosed after
chronic nasal discharge. Skull x-rays or CT scans
can be suggestive of a nasal tumor, however, the
diagnosis can only be confirmed with a biopsy. The
treatment of choice for nasal tumors is definitive
radiation therapy. Studies have shown that dogs with
nasal tumors treated with radiation therapy have a
median survival time of 1.3 years. Please consult
with a veterinary radiation oncologist to discuss
treatment options.
Oral
melanomas are the most common oral tumor in
the dog. The traditional treatment for this disease
consists of a combination of surgery and radiation
therapy. Studies have described a median survival
time ranging from 8 months to one year following
radiation therapy. A vaccine has recently become
available--the oral melanoma vaccine is used in an
attempt to prevent the spread of the tumor. It is
important that local control of the tumor be
achieved with a combination of surgery and radiation
therapy prior to the administration of the vaccine.
Soft
tissue sarcomas consist of a group of
tumors that share a similar biological behavior and
a similar response to treatment. This group includes
tumors such as Fibrosarcomas, Hemangiopericytomas ,
Nerve Sheath Tumors, and Myxosarcomas. Soft tissue
sarcomas are locally invasive and rarely spread to
other parts of the body. Surgical excision with 3-cm
margins can be curative. If wide surgical margins
are not possible radiation therapy is used control
this tumor. Studies have shown that 76% of patients
treated with a combination of surgery and radiation
therapy are disease-free 5 years following the
completion of treatment.




