Insulin-like growth factor-I and cancer mortality in older men.
BACKGROUND
Although numerous studies have explored the relation of IGF-I with cancer incidence, few have investigated the association between IGF-I and cancer mortality.


OBJECTIVE
This study examined the association of serum IGF-I levels with cancer mortality in older community-dwelling men.


METHODS
We conducted a prospective, population-based study of 633 men aged 50 yr and older (mean = 73) who attended a 1988-1991 research clinic visit when blood was obtained for measurement of IGF-I. Participants were followed for vital status through July 2006.


METHODS
All-cancer mortality was assessed.


RESULTS
Median IGF-I was 96 ng/ml. During the 18-yr follow-up, 368 deaths occurred; 74 (20%) were due to cancer. Cox regression analyses showed a significant quadratic association between IGF-I and all-cancer mortality (P = 0.039). Higher levels of IGF-I were associated with progressively higher risk of cancer death after adjusting for age, IGF-binding protein-1, adiposity, exercise, current smoking, and previous cancer. The adjusted risk of cancer death was statistically significant for IGF-I levels above 120 ng/ml, with magnitudes of effect ranging from 1.61 [95% confidence interval (CI) = 1.28-2.02] to 2.61 (95% CI = 1.46-4.64). For the 46% of men with IGF-I above 100 ng/ml, the risk of fatal cancer was 1.82 (95% CI = 1.11-2.96) compared to the risk with lower levels.


CONCLUSIONS
Higher serum IGF-I in older men is associated with increased risk of cancer death, independent of age, adiposity, lifestyle, and cancer history. These results suggest caution in the use of IGF-I-enhancing therapies to slow the adverse effects of aging.
Major
Jacqueline M
JM
Department of Family and Preventive Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093-0631C, USA.
Laughlin
Gail A
GA
Kritz-Silverstein
Donna
D
Wingard
Deborah L
DL
Barrett-Connor
Elizabeth
E
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D015999:Multivariate Analysis; D009369:Neoplasms / Q000097:blood* / Q000401:mortality*; D012044:Regression Analysis; D012306:Risk; D012307:Risk Factors; D011795:Surveys and Questionnaires
D018970:Insulin-Like Growth Factor Binding Protein 1; D007334:Insulin-Like Growth Factor I