Sex hormones have been implicated in the development of several cancer types, however few studies have assessed the associations of sex hormones with the incidence of common cancers.
To assess associations of testosterone (T) and its metabolites dihydrotestosterone (DHT) and estradiol (E2), with the incidence of prostate, colorectal and lung cancer in community-dwelling men aged ≥70 years.
Methods and participants
T, DHT and E2 were assayed using liquid chromatography-mass spectrometry between 2001-2004 in 4248 men. Outcomes until 20th June 2013 were ascertained using electronic linkage. Analyses were performed using competing-risks models, and adjustments were made for potential confounding factors. Results are expressed as subhazard ratios (SHR).
After exclusions, 3690 men were included in the analysis. There were 348, 137 and 107 cases of prostate, colorectal and lung cancers respectively. In the fully-adjusted analyses, T was not associated with the incidence of prostate cancer (SHR=1.00, 95% CI 0.90-1.12; p=0.939 per 1 SD increase in T). Similarly, no significant associations of free T, DHT and E2 were observed with prostate cancer incidence. Sex hormones were not associated with colorectal cancer incidence, however higher DHT was associated with an increased incidence of lung cancer (adjusted SHR=1.25, 95% CI 1.03-1.51; p=0.023 per 1 SD increase in DHT). When hormone parameters were assessed in quartiles, total and free T in the highest quartile were associated with an increased incidence of lung cancer compared to the rest of the quartiles (adjusted SHR=1.84, 95% CI 1.22-2.80; p=0.004 for total T; and adjusted SHR=1.85, 95% CI 1.19-2.88; p=0.006 for free T).
Sex hormones are not associated with incident prostate and colorectal cancer in older men. Higher T and DHT are independently associated with an increased incidence of lung cancer. Further studies warranted to investigate if a causal relationship exists.