Prostate Cancer - New Information from the National Cancer Institute
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Recent findings concerning prostate cancer were published in the Journal of the National Cancer Institute. A lengthy direct quote from the source has been included below as a means of relating this information as straightforwardly as possible.
The NCI research stated that, "The mitogenic and growth-stimulatory effects of insulin-like growth factors appear to play a role in prostate carcinogenesis, yet any direct association of circulating insulin levels and risk of prostate cancer remains unclear. We investigated the relationship of the level of serum insulin, glucose, and surrogate indices of insulin resistance (ie, the molar ratio of insulin to glucose and the homeostasis model assessment of insulin resistance [HOMA-IR]) to the development of prostate cancer in a case-cohort study within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort of Finnish men.
"We studied 100 case subjects with incident prostate cancer and 400 noncase
subjects without prostate cancer from the larger cohort. Fasting serum was
collected 5-12 years before diagnosis. We determined insulin concentrations with
a double-antibody immunochemiluminometric assay and glucose concentrations with
a hexokinase assay. Multivariable logistic regression models estimated relative
risks as odds ratios (ORs), and all statistical tests were two-sided. Insulin
concentrations in fasting serum that was collected on average 9.2 years before
diagnosis among case subjects were 8% higher than among non-case subjects, and
the molar ratio of insulin to glucose and HOMA-IR were 10% and 6% higher,
respectively, but these differences were not statistically significant.
"Among subjects in the second through fourth insulin quartiles, compared with those in the first quartile, increased insulin levels were associated with statistically
significantly increased risks of prostate cancer ! (OR = 1.50, 95% confidence
interval [CI] = 0.75 to 3.03; OR = 1.75, 95% CI = 0.86 to 3.56; and OR = 2.55,
95% CI = 1.18 to 5.51; for the second through fourth insulin quartiles,
respectively; P-trend = .02). A similar pattern was observed with the HOMA-IR
(OR = 2.10, 95% CI = 1.03 to 4.26; P-trend = .02) for the highest vs. lowest
quartiles.
"Risk varied inconsistently with glucose concentration (P-trend =
.38). A stronger association between insulin level and prostate cancer risk was
observed among leaner men and among men who were less physically active at work.
Crude prostate cancer incidence was 154 prostate cancers per 100 000
person-years in the lowest quartile of fasting serum insulin vs. 394 prostate
cancers per 100 000 person-years in the highest quartile."
This information is courtesy of D. Albanes and colleagues of the National Cancer Institute.
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