A recent study did indeed find a significant risk reduction associated with high serum levels of alpha-tocopherol, but this was in a cohort of smokers . This will not be discussed since it is assumed that the readers of this Newsletter, who presumable are very health conscious, by and large are non-smokers.
Another micronutrient which is the tomato.
that is frequently associated with prostate cancer is lycopene, the principal source of Early studies suggested that both tomato products and circulating lycopene were
associated eating lots
with a reduced risk of prostate of pizza. Bioavailability issues
cancer. Jokes were even made about the merits in this context of arose and it was found that products such as tomato paste were
preferable to raw tomatoes. Two recent publications relate to this matter, other a U.S. Food and Drug Administration (FDA) review done because make health claims for tomato products.
one a report on processed food
a follow-up trial, the producers wished to
The follow-up trial was part of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO). Participants were selected who underwent annual standardized screening for prostate cancer (PSA at entry and annually for 5 years and a digital rectal exam at entry and annually for 3 years). Thus this was a PSA-era study. No association was found between serum lycopene and total prostate cancer diagnosis risk or aggressive prostate cancer risk. The authors conclude that, consistent with other recent publications, these results suggest that lycopene or tomato-based regimens will not be effective in prostate cancer prevention .
The FDA report was based on a review of the literature and found “no credible evidence to support the association between lycopene intake and a reduced risk of prostate…cancer.” However, they mention finding very limited evidence to support the association between tomato consumption and reduced risks of prostate cancer .
This latter report prompted Edward Giovannucci, a very well known epidemiologist from Harvard, to write an editorial trying to reconcile the FDA position with earlier studies that did indeed show benefit. His thesis is that the newer studies fail to find benefit from lycopene or tomato products because the studies are all done in the PSA era. Before the widespread use of PSA testing for screening purposes, most cancers that were diagnosed had progressed to a relatively advanced stage. What was being detected were manifestations of advanced disease such as metastasis and tumor growth outside the prostate itself. In the PSA era, most of the cancers detected would never have attracted clinical attenuation and include small, low-grade and indolent tumors. Thus studies of tomatoes and lycopene in the PSA era with the endpoint of cancer diagnosis are looking at the question of benefits during the early stages of disease development, whereas in earlier times, the potential
benefit extended over Giovannucci points out
a much longer period in the that in the Health Professional’s
Follow-Up study (HPFS), the initial analysis of the
for the period 1986 to 1992 found an inverse association between incidence and the association was stronger for advanced cancer. was during the PSA era, the association was attenuated and
tomato sauce intake and total prostate cancer Later analysis for the period 1992-1998 which weak but a strong association persisted for
metastatic <1 serving
cancer. Combined per month. Finally
data for these two periods gave an analysis of the data found no
a 66% risk
for ≥ 2
servings per week sauce and the risk
diagnosis of organ-confined disease. advanced cancer were swamped by Giovannucci comments that only strict
Thus in the huge criteria for
the PSA era, the benefits of tomato sauce with regard to numbers of early non-advanced cases. In the HPFS study, aggressive behavior such as invasion into the seminal vesicle
or metastasis were prostate cancer. He the data needed are
adequate to detect the association between tomato also points out that the FDA review was not designed sparse.
paste and to take into
an increased risk of account these issues
These same observations apply to the PLCO study which was done in the PSA era. Thus it appears that tomatoes and lycopene provide benefit only in terms influencing advanced cancer or offering benefit that is only significant when the exposure is over the full initiation and progression of the disease, as was the case in the early studies. It would appear that abandoning cooked tomato products like tomato sauce, and as well even
supplemental lycopene, on the basis or recent studies is somewhat premature.
Furthermore, it may be
unrealistic to assume that studies will be carried out that might resolve the issues discussed, given the widespread PSA screening at present is the norm.
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