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Michael N Pollak

Publications and source records attributed to Michael N Pollak.

28 records · Page 2Linked to original sources
PubMed2003

Serum insulin-like growth factor I and subsequent risk of colorectal cancer among Japanese-American men.

Recent reports suggest that colorectal cancer is positively related to insulin-like growth factor I (IGF-I) and inversely related to insulin-like growth factor binding protein 3 (IGFBP-3). To evaluate these associations further and separately for colon and rectal cancer, the authors conducted a nested case-control study in a cohort of 9,345 Japanese-American men examined in Hawaii in 1971-1977. A total of 177 incident colon cancer cases and 105 incident rectal cancer cases were identified from 1972 to 1996. These patients' stored sera and those of 282 age-matched controls were measured for IGF-I and IGFBP-3. The adjusted mean level of IGF-I was higher in colon cancer cases than in controls (154.7 ng/ml vs. 144.4 ng/ml; p = 0.01). However, the multivariate odds ratio for the highest quartile compared with the lowest was just 1.8 (95% confidence interval: 0.8, 4.3). Adjusted mean IGF-I levels were similar between rectal cancer cases and their controls. For IGFBP-3, adjusted mean levels were lower for both colon and rectal cancer cases than for their matched controls, but the differences were not significant. The IGF-I results weakly support findings from other studies and suggest that there are differences in IGF-I findings between colon and rectal cancer cases. It is possible that IGF-related risk is confounded by other factors that may vary among different cohorts. Further research is needed to clarify these relations.

Age of Onset↗
PubMed2003

Challenges to cancer control by screening.

Population-based screening seems to be a common-sense strategy for controlling cancer, but recent reports have raised controversy concerning the benefits of common screening procedures. Intense efforts to develop and evaluate novel screening technologies are underway; however, effective use of any screening method must take into account any underlying biological considerations. What are these biological issues, and what challenges do clinicians face in screening for common cancers?

Biomarkers, Tumor↗
PubMed2003

Soy isoflavones in the treatment of prostate cancer.

Epidemiological studies suggest an inverse association between soy intake and prostate cancer (Pca) risk. We have previously observed that soy isoflavone genistein induces apoptosis and inhibits growth of both androgen-sensitive and androgen-independent Pca cells in vitro. To determine the clinical effects of soy isoflavones on Pca we conducted a pilot study in patients with Pca who had rising serum prostate-specific antigen (PSA) levels. Patients with Pca were enrolled in the study if they had either newly diagnosed and untreated disease under watchful waiting with rising PSA (group I) or had increasing serum PSA following local therapy (group II) or while receiving hormone therapy (group III). The study intervention consisted of 100 mg of soy isoflavone (Novasoy) taken by mouth twice daily for a minimum of 3 or maximum of 6 mo. Forty-one patients were enrolled (4 in group I, 18 in group II, and 19 in group III) and had a median PSA level of 13.3 ng/ml. Thirty-nine patients could be assessed for response. Soy isoflavone supplementation was given for a median of 5.5 (range 0.8-6) mo per patient. Although there were no sustained decreases in PSA qualifying for a complete or partial response, stabilization of the PSA occurred in 83% of patients in hormone-sensitive (group II) and 35% of hormone-refractory (group III) patients. There was a decrease in the rate of the rise of serum PSA in the whole group (P = 0.01) with rates of rise decreasing from 14 to 6% in group II (P = 0.21) and from 31 to 9% in group III (P = 0.05) following the soy isoflavone intervention. Serum genistein and daidzein levels increased during supplementation from 0.11 to 0.65 microM (P = 0.00002) and from 0.11 to 0.51 microM (P = 0.00001), respectively. No significant changes were observed in serum levels of testosterone, IGF-1, IGFBP-3, or 5-OHmdU. These data suggest that soy isoflavones may benefit some patients with Pca.

Administration, Oral↗
PubMed2003

Association of markers of insulin and glucose control with subsequent colorectal cancer risk.

We evaluated the association of plasma insulin and other markers of insulin and glucose control with subsequent colorectal cancer. Incident colon (n = 132) and rectal (n = 41) cancer cases and matched controls (n = 346) were identified between baseline in 1989 and 2000 among participants in a community-based cohort in Washington County, Maryland. Circulating markers of insulin and glucose control were measured in baseline blood samples. Body mass index (BMI) and use of medications to treat diabetes mellitus were self-reported at baseline. Conditional logistic regression was used to estimate matched odds ratios (ORs). Compared with the lowest fourth, participants with insulin concentrations in the highest fourth were not at an increased risk of colorectal cancer [OR, 0.78; 95% confidence interval (CI), 0.45-1.35; P(trend) = 0.24]. Similarly, no associations were observed for the ratio of total cholesterol:HDL-cholesterol, triglycerides, and insulin-like growth factor binding protein 1. However, those in the highest fourth of glycosylated hemoglobin (HbA(1c)) level had a slightly increased risk of colorectal cancer (OR, 1.57; 95% CI, 0.94-2.60; P(trend) = 0.02). The OR of colorectal cancer was 1.70 (95% CI, 1.01-2.86; P(trend) = 0.08) comparing BMI >/=30 kg/m(2) to <25 kg/m(2). The OR of colorectal cancer was 2.43 (95% CI, 1.10-5.38) for the use of medications to treat diabetes. The associations of higher HbA(1c), higher BMI, and the use of medications to treat diabetes, with colorectal cancer lend support to the hypothesis that perturbations in insulin and glucose control may influence colorectal carcinogenesis. It is possible that HbA(1c), BMI, and the use of medications to treat diabetes, as a surrogate for protracted or severe type 2 diabetes mellitus, may have been better time-averaged indicators of hyperinsulinemia and hyperglycemia than the plasma markers that were measured once prediagnostically in a nonfasting population.

Adult↗
PubMed2002

A sequence repeat in the insulin-like growth factor-1 gene and risk of breast cancer.

Insulin-like growth factor-1 (IGF-I), a potent mitogen, is hypothesized to influence breast cancer risk. In 3 previous studies, a polymorphism in the IGF-1 gene (sequence repeat length) was associated with plasma IGF-I level. We evaluated prospectively the relationships among a (CA)(n) repeat polymorphism in the IGF-1 gene, IGF-I level and breast cancer risk in a nested case-control study conducted within the Nurses' Health Study. Blood samples were collected in 1989-1990; up to June 1994, we identified 463 cases of breast cancer. One to 2 controls were selected per case, matched by age, menopausal status, postmenopausal hormone use, month and time of day of blood collection and fasting status, for a total of 622 controls. Although no significant trend was observed, plasma IGF-I levels were significantly lower among controls, with no copy of the 19 allele, compared with those homozygous for the 19 (CA)(n) repeat length (146 and 173 ng/ml, respectively; p-value for pairwise mean comparison = 0.005). In conditional logistic regression, controlling for established breast cancer risk factors, we observed no significant association between (CA)(n) repeat length genotype and risk of breast cancer [compared with repeat genotype 19/19-18/19 genotype relative risk (RR) = 0.96, 95% confidence interval (CI) = 0.56-1.64; 18/20 genotype RR = 0.92, 95% CI = 0.39-2.19; 19/20 genotype RR = 1.16, 95% CI = 0.82-1.64; 19/21 genotype RR = 0.69, 95% CI = 0.42-1.14; 20/20 genotype RR = 0.55, 95% CI = 0.28-1.10; 20/21 genotype RR = 0.72, 95% CI = 0.29-1.79]. Results did not vary substantially when evaluated according to menopausal status, tumor receptor status or category of other breast cancer risk factors. Although a modest association cannot be excluded, our data do not support an important relation between this IGF-1 gene polymorphism and breast cancer risk.

Adult↗
PubMed2002

Effects of lycopene supplementation in patients with localized prostate cancer.

Epidemiological studies have shown an inverse association between dietary intake of lycopene and prostate cancer risk. We conducted a clinical trial to investigate the biological and clinical effects of lycopene supplementation in patients with localized prostate cancer. Twenty-six men with newly diagnosed prostate cancer were randomly assigned to receive a tomato oleoresin extract containing 30 mg of lycopene (n = 15) or no supplementation (n = 11) for 3 weeks before radical prostatectomy. Biomarkers of cell proliferation and apoptosis were assessed by Western blot analysis in benign and cancerous prostate tissues. Oxidative stress was assessed by measuring the peripheral blood lymphocyte DNA oxidation product 5-hydroxymethyl-deoxyuridine (5-OH-mdU). Usual dietary intake of nutrients was assessed by a food frequency questionnaire at baseline. Prostatectomy specimens were evaluated for pathologic stage, Gleason score, volume of cancer, and extent of high-grade prostatic intraepithelial neoplasia. Plasma levels of lycopene, insulin-like growth factor-1, insulin-like growth factor binding protein-3, and prostate-specific antigen were measured at baseline and after 3 weeks of supplementation or observation. After intervention, subjects in the intervention group had smaller tumors (80% vs 45%, less than 4 ml), less involvement of surgical margins and/or extra-prostatic tissues with cancer (73% vs 18%, organ-confined disease), and less diffuse involvement of the prostate by high-grade prostatic intraepithelial neoplasia (33% vs 0%, focal involvement) compared with subjects in the control group. Mean plasma prostate-specific antigen levels were lower in the intervention group compared with the control group. This pilot study suggests that lycopene may have beneficial effects in prostate cancer. Larger clinical trials are warranted to investigate the potential preventive and/or therapeutic role of lycopene in prostate cancer.

Adenocarcinoma↗
PubMed2002

Dietary correlates of plasma insulin-like growth factor I and insulin-like growth factor binding protein 3 concentrations.

Plasma levels of insulin-like growth factor I (IGF-I) have been associated with risk of several cancers. Although protein-calorie malnutrition is known to decrease IGF-I levels, few published studies have related diet to IGF-I levels in well-nourished humans. We examined the cross-sectional association of plasma IGF-I and IGF-binding protein 3 (IGFBP-3) levels with intakes of alcohol, energy, macronutrients, micronutrients, and specific foods in 1037 healthy women. Adjusted mean hormone levels across categories of dietary variables were calculated by linear regression. Results were adjusted for non-dietary factors found to be associated with IGF levels. Total energy intake was positively associated with IGF-I levels when adjusted for covariates. Adjusted mean levels of IGF-I (ng/ml) across increasing quintiles of energy intake were 181, 185, 191, 199, and 195 (P for the linear trend = 0.006). In other multivariate analyses, energy-adjusted fat and carbohydrate intake had no association with IGF-I levels. The most consistent finding was a positive association between protein intake with circulating IGF-I concentration (174, 188, 201, 192, and 196 ng/ml across quintiles of protein intake; P = 0.002), which was largely attributable to milk intake. Adjusted mean levels of IGF-I (ng/ml) across increasing quartiles of milk intake were 183, 189, 188, and 200 (P = 0.01). Higher fat intake, in particular saturated fat, was associated with lower levels of IGFBP-3. We conclude that higher energy, protein, and milk intakes were associated with higher levels of IGF-I. These associations raise the possibility that diet could affect cancer risk through influencing IGF-I level.

Aged↗
PubMed2002

Lifestyle correlates of plasma insulin-like growth factor I and insulin-like growth factor binding protein 3 concentrations.

Plasma levels of insulin-like growth factor I (IGF-I) have been associated with risk of a number of cancers and other diseases. We examined the cross-sectional association of plasma IGF-I and IGF-binding protein 3 (IGFBP-3) levels with age, smoking, physical activity, and reproductive and menopausal factors in 1037 healthy women. Adjusted least-square mean hormone levels across categories of lifestyle factors were calculated by linear regression. Age was inversely associated with IGF-I levels. In multivariate analyses, a higher body mass index (BMI) was associated with higher IGFBP-3 levels (BMI <21 versus >/=29 kg/m(2), 3879 versus 4080 ng/ml; P for trend = 0.01). Current use of hormone replacement therapy (HRT) was associated with a lower IGF-I, with oral estrogen being associated with the lowest levels (non-use of HRT versus oral estrogen + progesterone versus oral estrogen: 181 versus 143 versus 116 ng/ml; P for all comparisons </= 0.005). Higher parity was also associated with lower levels of IGF-I (no pregnancies versus >/=4: 212 versus 180 ng/ml; P for trend = 0.003). We conclude that age and HRT use, particularly oral estrogen alone, were inversely associated with IGF-I levels. BMI was positively associated with IGFBP-3 levels. This is the first report of an inverse association of circulating IGF-I levels with parity. This association may represent one mechanism by which parity exerts its protective effect on some cancers.

Aged↗