NEW YORKTotal mesorectal excision (TME) has reduced the risk of local
recurrence in rectal cancer, but adjuvant therapy is still needed in
node-positive cases, according to Bruce Minsky, MD, vice chairman of radiation
oncology at Memorial Sloan-Kettering Cancer Center in New York.
"We may not need to treat all patients with T3 and/or N0 disease with
postoperative adjuvant therapy, but the INT 0114 data show that there are still
local failures and decreased survival even after 5 years," Dr. Minsky said.
"Retrospective trials have identified favorable subsets of patients with T3, N0
disease who have 10-year actuarial local recurrence rates of less than 10%
after surgery alone, but this has yet to be confirmed in a randomized trial."
Preoperative chemoradiotherapy is replacing postoperative adjuvant therapy
as the favored approach. "In most countries outside of northern Europe, this is
usually given as combined chemoradiotherapy," Dr. Minsky said. "Potential
advantages include decreased tumor seeding, less acute toxicity, increased
radiosensitivity, and enhanced sphincter preservation. The primary disadvantage
is the risk of overtreating patients with either early stage disease or
undetected metastatic disease."
Dr. Minsky described retrospective studies showing that preoperative
combined chemoradiotherapy increases pathologic downstaging compared to
preoperative treatment with radiation alone. Most regimens also include a
postoperative chemotherapy component, and Dr. Minsky said that the ongoing
randomized European Organization for Research and Treatment of Cancer (EORTC)
22921 trial is examining this issue.
Twelve randomized trials of preoperative radiation therapy without
chemotherapy have been reported. Only one, the Swedish Rectal Cancer Trial,
reported a survival advantage. Two meta-analyses of preoperative radiation
therapy reported conflicting results. The standard approach outside of selected
northern European countries is to use both chemotherapy and radiation.
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