20 / 32
Long-chain omega-3 fatty acids and dark-meat fishmay improve
disease-free survival in colon cancer
L
ong-chain omega-3 fatty acids and dark-
meat fish have been shown to improve
disease-free survival in patients with
colon cancer, with an 80% improvement
in patients with tumours exhibiting high
cyclooxygenase-2 (COX2) expression.
This was the finding of a prospective, feder-
ally funded cohort study utilising data from
the Alliance for Clinical Trials in Oncology,
Cancer and Leukemia Group B.
Erin L. Van Blarigan, ScD, of the University
of California, San Francisco, explained that
long-chain omega-3 fatty acids may prevent
colon cancer progression, but data in humans
are lacking.
Dr Van Blarigan and colleagues hypothesised
that long-chain omega-3 fatty acids and dark-
meat fish intake after colon cancer diagnosis
would be associated with longer disease-free
survival, particularly among patients whose
tumours expressed COX2.
A total of 1011 patients with stage 3 colon
cancer were enrolled in an adjuvant chemo-
therapy trial from 1999–2001. Intake of
dark-meat fish; canned tuna; breaded fish;
shrimp, lobster, scallops, clams; other fish;
and fish oil supplements was assessed via
a food frequency questionnaire during and
6 months after therapy. Fewer than 5% of
patients reported taking fish oil supplements.
Hazard ratios and 95% confidence intervals
for disease- and recurrence-free survival,
as well as overall survival, were estimated,
adjusting for clinical, sociodemographic, and
lifestyle factors. In a subset of 510 patients,
the investigators determined whether tumour
COX2 expression modified the association
between long-chain omega-3 fatty acid intake
and disease-free survival.
A total of 343 colon cancer recurrences and
305 deaths (7 years median follow-up) were
observed. Higher long-chain omega-3 fatty
acid intake after colon cancer diagnosis was
associated with 28% improved disease-free
survival [HR for highest vs lowest quartile
0.72 (0.54, 0.97); P = 0.03].
The association was driven by reduced risk
of colon cancer recurrence (HR for recur-
rence-free survival for the highest vs lowest
quartile 0.68 [0.50, 0.94]; P = 0.01; HR for
overall survival for the highest vs lowest quar-
tile 0.79 [0.56, 1.13]; P = 0.17).
Among patients with tumours that had mod-
erate to high expression of COX2, long-chain
omega-3 fatty acid intake was associated with
80% improved disease-free survival (HR for
the highest vs lowest quartile 0.2 [0.06–
0.76]; P = 0.006).
When dietary sources of long-chain omega-3
fatty acids were examined, patients who con-
sumed dark-meat fish more than three times
per month vs none experienced longer dis-
ease-free survival (HR 0.65 [0.48, 0.87]; P
= 0.007); recurrence-free survival (HR 0.63
[0.46, 0.86]; P = 0.007), and overall survival
(HR 0.68 [0.48, 0.96]; P = 0.04). No other
fish or seafood was associated with disease-
or recurrence-free survival or overall survival.
No other fish or seafood was associated with
disease- or relapse-free survival or overall
survival.
Dr Van Blarigan concluded that long-chain
omega-3 fatty acids and dark-meat fish
intake may improve disease-free survival in
colon cancer, especially among patients with
tumours of high COX2 expression.
PracticeUpdate Editorial Team
© ASCO/Todd Buchanan 2017
CONFERENCE COVERAGE
20
PRACTICEUPDATE HAEMATOLOGY & ONCOLOGY