Transcript Radiotherapy in gastric cancer

Radiotherapy in gastric cancer
SH. Molana M.D
Radiation oncologist
Neoadjuvant
Adjuvant
Curative
Palliative
Neoadjuvant Radiation therapy
the
results of a phase III study from
Beijing demonstrated a survival benefit for
patients with gastric cardia carcinoma
receiving preoperative irradiation and
surgery versus surgery only
Neoadjuvant Radiation therapy
Since
preoperative radiation therapy and
chemotherapy have improved the surgical
outcome in patients with rectal and
esophageal cancer, this is a logical
approach to explore in gastric cancer as
well.
Neoadjuvant Radiation therapy
Although
no phase III trials have tested the value
of preoperative radiation plus chemotherapy for
patients with gastric cancer, two phase III trials for
patients with esophagus cancer have included
either lesions of the gastric cardia (143) or the
esophagogastric junction (84). In both trials, the
trimodality arm demonstrated an improvement in
survival when compared with the control arm of
surgery alone.
Preoperative chemoradiation data for patients
with gastric cancer is limited to phase II
Neoadjuvant Radiation therapy
Preliminary
uncontrolled data suggest that with
preoperative combined modality therapy
(chemoradiotherapy with or without induction
chemotherapy), approximately 70 percent of
patients with localized but initially unresectable
gastric cancer can undergo potentially curative
resection, with pathologically complete response
rates as high as 30 percent
Although these early data seem encouraging, the
studies have been conducted in highly selected
patients, and randomized trials will ultimately be
necessary to confirm benefit from any of these
approaches over chemoradiotherapy alone.
Adjuvant Therapy
80 percent of patients who die from gastric
cancer experience a local recurrence at some
time in their illness
The term adjuvant therapy is best used to
describe additional treatment in an attempt to
increase cure rates in patients who have already
undergone a potentially curative resection
For gastric cancer, an R0 surgical procedure, in
which all gross disease has been removed, the
margins of resection are microscopically negative,
and no distant metastases were found, is required
before adjuvant therapy is considered
Resections that leave microscopic or gross
residual disease are not adjuvant treatment, but
rather therapy of known residual cancer
Adjuvant Therapy
patients
with early stage gastric cancers
(e.g., AJCC stage 1A) have a good to
excellent chance of cure with surgery
alone
patients with more advanced stages, even
if all visible disease has been resected with
negative microscopical margins, have a far
worse outcome
Adjuvant Therapy
Clinical
studies performed in the past
not infrequently allowed a delay of up to
eight to 12 weeks after operation before
beginning Adjuvant Therapy
Relatively few studies have evaluated
radiation therapy alone (with no
concomitant chemotherapy) as an adjuvant
to surgical resection of gastric cancer
Adjuvant
radiotherapy improved the overall
survival
no survival advantage
other radiation approaches have been tried
including intraoperative electron beam radiation
therapy
patients receive a single dose of high-energy
electrons delivered to the tumor bed at the time
of gastrectomy [improved 5-year survival (20%) in
patients with locally advanced disease ]
Adjuvant Therapy
Most
of the studies that have evaluated radiation
therapy as an adjuvant have used concomitant 5-FU
chemotherapy
Radiation for Palliation
no
studies have evaluated the use of
radiation therapy in patients with locally
recurrent or metastatic carcinoma of the
stomach
Its use is likely to be limited to palliation
of symptoms such as bleeding or
controlling pain secondary to local tumor
infiltration
Technique of Radiation Therapy
Generally
gastric radiation therapy emphasizes
anteroposterior-posteroanterior fields as this
minimizes the total volume of normal tissue that
is irradiated
Intensity modulated radiation techniques and
split field techniques are at times very useful in
obtaining an improved dose distribution.
Generally a dose of 45 Gy given at 1.8 Gy/d has
a low chance of producing significant late
complications
At doses higher than 50 Gy, the risk of late
complications increases, and these doses should
be limited to very small volumes in those who are
at high risk for recurrence
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