Evidence for cure by adjuvant therapy in colon cancer: observations based on individual patient data from 20,898 patients on 18 randomized trials.
OBJECTIVE
Limited data are available on the time course of treatment failures (recurrence and/or death), the nature and duration of adjuvant treatment benefit, and long-term recurrence rates in patients with resected stage II and III colon cancer.


METHODS
The data set assembled by the Adjuvant Colon Cancer Endpoints Group, a collection of individual patient data from 18 trials and more than 20,800 patients testing fluorouracil-based adjuvant therapy in patients with stage II or III colon cancer, was analyzed.


RESULTS
A significant overall survival (OS) benefit of adjuvant therapy was consistent over the 8-year follow-up period. The risk of recurrence in patients treated with adjuvant chemotherapy never exceeds that of control patients, signifying that adjuvant therapy cures some patients, as opposed to delaying recurrence. After 5 years, recurrence rates were less than 1.5% per year, and after 8 years, they were less than 0.5% per year. Significant disease-free survival (DFS) benefit from adjuvant chemotherapy was observed in the first 2 years. After 2 years, DFS rates in treated and control patients were not significantly different, and after 4 years, no trend toward benefit was demonstrated. This benefit was primarily driven by patients with stage III disease.


CONCLUSIONS
Adjuvant chemotherapy provides significant DFS benefit, primarily by reducing the recurrence rate, within the first 2 years of adjuvant therapy with some benefit in years 3 to 4, translating into long-term OS benefit. This reflects the curative role of chemotherapy in the adjuvant setting. After 5 years, recurrence rates in patients treated on clinical trials are low, and after 8 years, they are minimal; thus, long-term follow-up for recurrence is of little value.
Sargent
Daniel
D
Division of Biomedical Statistics and Informatics, Mayo Clinic, 200 1st St SW, Rochester, MN 55905, USA. sargent.daniel@mayo.edu
Sobrero
Alberto
A
Grothey
Axel
A
O'Connell
Michael J
MJ
Buyse
Marc
M
Andre
Thierry
T
Zheng
Yan
Y
Green
Erin
E
Labianca
Roberto
R
O'Callaghan
Chris
C
Seitz
Jean Francois
JF
Francini
Guido
G
Haller
Daniel
D
Yothers
Greg
G
Goldberg
Richard
R
de Gramont
Aimery
A
D000964:Antimetabolites, Antineoplastic / Q000627:therapeutic use*; D017024:Chemotherapy, Adjuvant; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000601:surgery; D003131:Combined Modality Therapy; D005472:Fluorouracil / Q000627:therapeutic use*; D005500:Follow-Up Studies; D006801:Humans; D016032:Randomized Controlled Trials as Topic; D016019:Survival Analysis
D000964:Antimetabolites, Antineoplastic; D005472:Fluorouracil