RESUMO
BACKGROUND: Obesity and weight gain after the diagnosis of prostate cancer are associated with an increased risk of prostate cancer recurrence and mortality; individualized plans to help prostate cancer survivors maintain or lose weight may be beneficial for recurrence risk reduction. Herein, we explore whether gains in cardiovascular fitness predict successful weight loss in men participating in a weight loss trial (NCT01886677). METHODS: Forty men were randomized to receive twice-weekly in-person and telephone-based guidance on calorie-restricted diets and aerobic exercise to promote ~0.91 kg/week weight loss, or wait-list control. Thirty-two men completed submaximal VO2 Treadmill Tests (TT), anthropometric measures and two 24-hour dietary recalls at baseline and follow-up. For this secondary analysis, study arms were combined and associations between baseline and longitudinal changes in physiological effort (PE, measured by heart rate during TT), predicted VO2max, caloric intake and weight loss were analyzed. RESULTS: Men lost 3.4 kg in 50 ± 23 days on the study. Multivariate linear regression indicated weight change was associated with change in PE at stage 2TT (Partial R = 0.635, p < 0.001), days on study (Partial R = -0.589, p = 0.002) and change in caloric intake (Partial R = 0.457, p = 0.019). CONCLUSIONS: Untrained men experiencing elevated heart rates during stage 2TT at baseline were able to achieve greater weight loss over the study period; this association was strengthened by a decrease in PE at the same level from baseline to follow-up concomitant with reduced caloric intake. Therefore, for these middle-aged and older men with lower aerobic fitness, exercise appears to be a key factor in achieving higher degrees of weight loss.
RESUMO
BACKGROUND: Poor diet and insufficient physical activity are strongly associated with an increased risk of several cancers. Preclinical studies suggest that lifestyle modifications may exert favorable effects on tumor biology. Randomized controlled trials in the presurgical setting serve as an ideal means to translate this research to humans; however, little is known about the characteristics of patients who enroll in these presurgical trials versus those who do not. METHODS: Screening databases from three presurgical lifestyle intervention trials for breast and prostate cancer patients conducted at Duke University Medical Center (NCT00049309) and the University of Alabama at Birmingham (NCT02224807 and NCT01886677) were combined for analysis. Demographic and anthropometric differences between enrolled vs. non-enrolled individuals were assessed using Chi-square for categorical variables and t-tests for continuous variables. RESULTS: There was no difference in participation rate when comparing minority status or overweight and obese patients. However, obese females were slightly more likely to enroll than women who were overweight (p = 0.110), a trend not seen in men. Women were also less likely than men to participate if their study site was >25 miles from their home (p = 0.034). Patients who had completed a college degree were somewhat less likely to enroll than those with less educational attainment (p = 0.072). Of those who did not enroll, 80% cited a lack of time. CONCLUSION: Similar to other clinical trials, lack of time is a leading barrier to enrollment, and travel/distance appears to be a greater barrier for women in presurgical studies. Larger presurgical lifestyle intervention trials will require tailored strategies to enhance recruitment.
