ROCHESTER, MinnesotaSummarizing cooperative group approaches to adjuvant
treatment of colorectal cancer, Charles Erlichman, MD, noted: "Treatment for
stage II colon cancer remains controversial. Treatment for stage III colon
cancer should be fluorouracil (5-FU)/leucovorin. Treatment for stage III rectal
cancer should be radiation plus fluorouracil/leucovorin. The results of
three-drug regimens are pending, as are data on the role of COX-2 inhibitors
and of targeted agents such as epidermal growth factor receptor (EGFR) or
tyrosine kinase inhibitors." Dr. Erlichman is professor of oncology, Mayo
Clinic, Rochester, Minnesota.
The current standard of care for stage II colon cancer is based on several
major studies. "The International Multicentre Pooled Analysis of Colon Cancer
Trial (IMPACT) analysis, which I was involved in, compared 5-FU/leucovorin to
observation and found a nonsignificant 2% difference in overall survival," Dr.
Erlichman said. Similarly, a study of insurance claims for over 3,700 stage II
patients in New York, reported by Schrag et al in a presentation at the
American Society of Clinical Oncology Meeting in 2001 (ASCO abstract 488),
found that adjuvant therapy improved 5-year survival by only 2%, from 72% to
74%. The result has been a lack of agreement, according to Dr. Erlichman, with
the National Surgical Adjuvant Breast and Bowel Project (NSABP) recommending
adjuvant chemotherapy for all Dukes stage B patients and the IMPACT trial
advising no adjuvant therapy for patients with stage II colon cancer.
Age Alone Is No Barrier
Dr. Erlichman said that 5-FU/leucovorin is the current standard adjuvant
treatment and increases 5-year survival from about 50% to about 70% in mixed
populations of stage II and stage III colon cancer. A pooled analysis drawn
from several phase III trials looking at age concluded that age alone is no
barrier to adjuvant chemotherapy. Dr. Erlichman pointed out, however, that the
mixture of stage II and stage III patients in these studies makes adjuvant
chemotherapy for stage II colon cancer controversial.
"Because of this controversy, intergroup study C9581 was started with a plan
to treat 2,100 patients with stage II colon cancer. About 1,700 patients have
been enrolled on the study. The drug supply ran out in June 2002 due to a
negative study in stage III disease. Patients are still being followed, but we
will have to wait much longer than was originally planned to be able to ferret
out whether this drug has any utility," Dr. Erlichman said.
Newer Regimens Tested
The VICTOR study being conducted in Europe is examining the effect of a
COX-2 inhibitor on colon cancer. The trial has enrolled 200 of a planned 700
patients with stage II or stage III colon cancer, Dr. Erlichman reported. "The
idea is to put everybody on the trial, and if there are enough patients, you
will get answers."