Epidemiological associations of metabolic factors with cancer risk and cancer late effects

There is interest in developing our knowledge of modifiable cancer risk factors. The three studies in this dissertation investigate the role of metabolic factors at two points along the cancer control continuum: etiology and treatment late-effects.; The first two studies examined questions of cancer etiology. The first examined the hypotheses that the metabolic syndrome and physical inactivity are associated positively with incident colorectal cancer in a large prospective cohort of men and women. There was a dose-response association between colorectal cancer and the number of metabolic syndrome components present at baseline (Ptrend: 0.05) after multivariate adjustment. Metabolic syndrome (≥ 3 vs. 0 components) was associated positively with age- and gender-adjusted colorectal cancer (RR: 1.71 [95% CI: 1.1, 2.7]); this association was attenuated after multivariate adjustment (RR: 1.49 [0.9, 2.4]). The multivariate-adjusted association was strong in men (RR: 2.20 [1.1, 4.3]) and absent in women (RR: 1.01 [0.5, 2.0]). There was no association between physical activity and colorectal cancer (Sports Index Q4 vs. Q1 RR: 0.82 [0.5,1.2]).; The second study examined the hypothesis that a randomized 39-week strength-training intervention in 57 women would increase insulin-like growth factor binding-protein (IGFBP)-2 levels in the treatment versus control group. Further analyses examined cross-sectional and longitudinal associations between body fat, insulin, and IGF-axis proteins (IGF-I and IGFBPs-1, -2, and -3). No intervention effect was observed for IGFBP-2 levels over 15 or 39 weeks (2-sided regression: p = 0.97 and p = 0.91, respectively). Body fat and insulin were inversely associated with IGFBP-1 and -2, but were not associated with IGF-I and IGFBP-3, at baseline and over 39 weeks.; The third project examined cancer late-effects and examined the hypotheses that a randomized twice-weekly strength training intervention in 78 recent breast cancer survivors would not increase the incidence of lymphedema or its symptoms. Incidence of clinically diagnosed lymphedema between baseline and six-months was 6.4% and 5.9% in the treatment and control groups, respectively (p = 0.54). Self-report symptoms did not vary between the two groups at six months (p = 0.24). No participant experienced a change in arm circumference measures after the intervention.