TAP Vol 4 Issue 16 by Harborside Press LLC

ASCOPost.com | OCTOBER 15, 2013

PAGE 147

In the Literature

each of the study participants as part of the NHANES laboratory examination and used to determine total and percentage free PSA. “Low percentage free PSA has recently been shown to better predict aggressive disease and to improve the specificity in predicting disease compared with using total PSA alone,” the authors explained. “To further evaluate the relationship between shiftwork and PSA level, we created a combined variable to define those with high risk of developing aggressive disease, including only those with percentage of free PSA less than or equal to 25% and total PSA of 4.0 ng/mL or greater compared with those defined as low risk, including only those with percentage free PSA greater than 25% and total PSA less than 4.0 ng/mL.”

Key Findings Among shiftworkers, 5.6% had a total PSA level of 4.0 ng/mL or greater, compared to 2.8% of nonshiftworkers. Adjusted for age, BMI, race/ethnicity, health insurance, average hours of sleep per night, and months on the current job, the multivariable model odds ratio for having total PSA 4.0 ng/mL or greater among shiftworkers compared to nonshiftworkers was 2.62 (95% CI = 1.16–5.95; P = .02). “In comparisons of high and low risk for aggressive disease, 5.6% of shiftworkers fell into the high risk category compared with 2.6% of nonshiftworkers,” the authors wrote. Adjusted for age, BMI, race/ethnicity, health insurance, average hours of sleep per night, and months on the current job, the multivariate model odds ratio for having a total PSA result of 4.0 ng/mL or greater and a free PSA result less than or equal to 25% among shiftworkers compared to nonshiftworkers was 3.13 (95% CI = 1.38–7.09; P = .01). The investigators explained that they also “examined the relationship between shiftwork and PSA values by sextile categories (<1.01, 1.01–2.00, 2.01–3.00, 3.01–4.00, 4.01–10.00, >10.00) that have been shown to be predictive of future prostate cancer development.” Results showed that for men aged 45 years or older with total PSA levels of 1.00 ng/ mL or less, the absolute risk of future prostate cancer and mortality was less than 1.6%. “ In contrast, for men with a PSA value of 10.00 ng/

mL or greater, the risk of developing prostate cancer was 35% for men aged less than 45 years, 41% for men aged 45 to 49 years, and increased stepwise to 88% for men aged greater than 75 years. Likewise, the absolute risk of mortality for men with a PSA value of 10.00 ng/mL or greater was 9.8% for men aged less than 45 years, 16% for men aged 45 to years 49, and increased to a peak risk of 52% among men aged 60 to 64 years. Based on these projections, it is likely that a greater proportion of the shiftworkers in our dataset will develop and die from prostate cancer in their lifetimes,” the researchers wrote. “The World Health Organization categorized shiftwork involving circadian desynchrony as a ‘probable carcinogen’ based on studies of breast cancer risk in female shiftworkers. This study supports the notion that shiftwork may relate to an increased risk in prostate cancer among men,” the authors stated. Flynn-Evans EE, et al: J Natl Cancer Inst 105:1292-1297.

PANCREATIC CANCER High-Quality Diet May Reduce Risk Consuming a high-quality diet, consistent with the Dietary Guidelines for Americans 2005, may reduce the risk of pancreatic cancer, a dietary pattern analysis study found. “This finding contrasts with previous studies showing limited associations with specific foods or nutrients,” the authors reported in the Journal of the National Cancer Institute ( JNCI). Dietary pattern analysis, however, “may better predict disease risk than individual food or nutrient intakes for several reasons,” the authors stated. These reasons include possible biologic interaction or synergy between foods and it may be easier to detect diet-related associations with disease by comparing overall diets of poor or high quality rather than intake of an isolated food or nutrient. Adherence to the Dietary Guidelines for Americans 2005 was measured by the Healthy Eating Index 2005 (HEI-2005). Using responses to food frequency questionnaires returned in 1995 and 1996, the investigators calculated the HEI-2005 score for 537,218 men and women in the National Institutes of Health-Amer-

ican Association of Retired Persons Diet and Health Study, including 2,383 identified with incident, exocrine pancreatic cancer. Participants who met the most dietary guidelines had a statistically significant reduced risk of pancreatic cancer compared with those who met the fewest guidelines (hazard ratio [HR] = 0.85, 95% CI = 0.74 to 0.97). There was also a statistically significant interaction with the HEI2005 score and body mass index (BMI) among men (P = .03) but not in women (P = .24). This interaction was stronger among overweight and obese men than among men of normal weight.

Qualifying Remarks “HEI-2005 was not specifically designed for the purpose of overall cancer prevention,” the authors noted. “Also, the [food frequency questionnaire] measured consumption in categories, thus not capturing specific food intakes beyond the maximum category. However, the HEI-2005 score accounts for total calories and was designed to include limits for moderation components, accounting for excess consumption of foods thought to contribute to poor health outcomes.” An editorial accompanying the JNCI article pointed out that in the time since the article was submitted, the U.S. Department of Agriculture and the National Cancer Institute “have released another update to the index, the HEI–2010. This more recent index incorporates specific dietary guidance that was added to the

2010 Dietary Guidelines for Americans, including increased evidence that inclusion of finfish and shellfish and limitations on refined grain consumption were important components of healthy dietary patterns. Other components of the HEI–2005 were renamed or slightly modified for the HEI–2010 to better reflect current evidence.” Three large U.S. cohorts, including the NIH-AARP cohort, are being analyzed with the HEI–2010 and other dietary pattern indices, such as the Mediterranean Diet Score, in relation to cancer-specific, cardiovascular-specific, and total mortality. “Using data from the NIH–AARP Diet and Health Study, the MultiEthnic Cohort Study, and the Women’s Health Initiative, investigators in the Dietary Patterns Methods Project are applying consistent and standardized methodology across the cohorts to examine the associations of index-based scoring systems for dietary patterns with total and disease-specific mortality outcomes,” the editorial continued. Similar to the results of the earlier study, “it is hoped that the type of evidence obtained from Dietary Patterns Methods Project analyses can inform public health nutrition guidance in more meaningful and practical ways than would reductionist analyses focusing on single foods or nutrients.” n Arem J, et al: J Natl Cancer Inst105:1298–1305, 2013. Ballard-Barbash R, et al: J Natl Cancer Inst105:1265–1267, 2013.