An oncologist at the University of California San Francisco (UCSF) has found that dietary risk factors are closely associated with incidence of prostate cancer (CaP).
June Chan from UCSF presented his study on Nutritional Epidemiology of Prostate Cancer.
Dietary risk factors that increase risk of CaP include foods high in calcium (and possibly processed foods and red meats) and foods that decrease risk include foods rich in lycopene and selenium (and possibly legumes, vegetables, Vit E, antioxidants, fish and marine n-3 fatty acids).
According to a population migration study, low-risk CaP populations moving to a high-risk area shifted to a higher risk profile. Chinese men in China had a CaP risk of 3/100,000, but after moving to the US this risk elevated to 100-120/100,000 by three generations later. This supports the notion that epigenetic events contribute to CaP risk.
Epigenetic factors play a role in the process of cellular differentiation, allowing cells to stably maintain different characteristics despite containing the same genomic material.
However, Chan said that from an epidemiologic standpoint there are interpretation limitations that can influence the presumed risk factors.
CaP heterogeneity will affect the outcomes and one should take into account that incidence vs. progression vs. mortality are carefully defined in studies. Among incident cases, there must be a clear line of distinction between aggressive vs. non-aggressive disease. The influence of PSA screening and other interactions must also be considered.
Take for example, CaP heterogeneity influences the incidence percentage of high-risk vs. low-risk CaP among those taking either lycopene based foods or calcium. Also, the interaction of antioxidant intake and the MnSOD genotype, showing the influence of genotype on nutrition is surprising.
In the CaPSURE database, diet and CaP progression were analyzed by multivariate analysis. Most patients included in June's analysis had low or intermediate risk CaP (70 pc and 25 pc, respectively). A protective effect of vegetables was noted, excluding fish.
The study was presented by Chan, ScD at the American Society of Clinical Oncology (ASCO) - 2008 Genitourinary Cancers Symposium - A Multidisciplinary Approach.