The prostate has become a common focus of discussion in health related media outlets, but it would be wrong to assume that most people know what the prostate is. The prostate is a male reproductive organ about the size of a golf ball, growing around the urethra (the urinary channel) as it leaves the bladder. Its function is to make semen, the nutrient fluid in which the sperm lives.
The prostate can be the cause of many problems in men and the consternation is compounded by the confusion surrounding the media cacophony about screening for prostate cancer and the usefulness of PSA (prostate specific antigen) in this regard. Prostate cancer is one of the most commonly diagnosed cancers among men in the United States. Prostate cancer is not only prevalent, but also slow growing. Only 0.6% of diagnosed prostate cancer patients die within 5 years. (NCI SEER data) This makes it difficult to decide how and if to treat the prostate cancer. The main question becomes: is the cancer significant enough to require treatment? Not all prostate cancers are the same. Age, Gleason score, stage, co-morbidities, all contribute to outcomes. The AUA has come out publicly with the statement that prostate cancer is over diagnosed and over treated and active surveillance is an acceptable option.
The main marker used to screen for prostate cancer is the PSA. However this elevated in benign conditions as often as it is in the presence of prostate cancer. The PSA is a protein made by prostate cells, which can be found in increased amounts in the blood in conditions where the vascularity of the prostate increases. This can occur in both malignant as well as inflammatory conditions, as in prostatitis. The PSA is not diagnostic of prostate cancer, but taken in context with other clinical information obtained during evaluation, can help in diagnostic and treatment related decision-making by experienced physicians.
Although there is debate regarding the role of diet in prostate cancer, some clear trends have emerged:
- Prostate cancer rates vary widely between countries and ethnicities.
- Prostate cancer rates are higher in societies with “Western” diets and lifestyles.
- These higher cancer rates follow the adoption of Western eating practices.
Prostate cancer has been shown to have a genetic component with a three-fold increase in incidence in first-degree relatives. However, environmental factors also play an important and possibly a decisive role in the appearance of this disease. There is a three-fold increased incidence in prostate cancer between Asians (88/100,000) and Blacks in the US (233/100,000). What are the main dietary differences between Western and developing countries? The emphasis is on animal-based foods in the former, versus plant-based foods in the latter.
There is a large amount of evidence pointing to animal derived fat as playing a role in the development of prostate cancer. What are the mechanisms for this? The first mechanism involves a hormone that increases cancer cell growth. This is a growth hormone called Insulin-like Growth Factor 1 (IGF-1). It turns out that consuming animal-based foods increases the blood level of this growth hormone.
Vitamin D metabolism has also been implicated in prostate cancer. Our bodies can make all the Vitamin D we need by exposure to the sun. This Vitamin D gets transformed to the active form 1,25 D in the kidney. This active form of Vitamin D is 1,000 times more active than the non-active form, and acts in preventing cells in becoming diseased. Animal protein-containing foods cause a significant decrease in 1,25 D. Another cause of decreased 1,25 D is too much calcium in the diet. All these variable pathways can interact in unexpected ways to lead to adverse effects in these intricate networks. The take home-message regarding diet, to quote Michael Pollan, the healthy food advocate:
“Eat food. Not too much. Mostly plants.”