prostate cancer and diet

[Wuzzy]

hi guys, this article is wicked to read in full..

1: Int J Cancer 2002 Mar 10;98(2):262-7

Incidence and mortality of testicular and prostatic cancers in
relation to world dietary practices.

Ganmaa D, Li XM, Wang J, Qin LQ, Wang PY, Sato A.

Department of Environmental Health, Medical University of
Yamanashi, Tamaho, Yamanashi, Japan.

The incidence and mortality rates of testicular and prostatic
cancers in 42 countries were correlated with the dietary
practices in these countries using the cancer rates (1988-92)
provided by the International Agency for Research on Cancer
(IARC) and the food supply data (1961-90) provided by the Food
and Agriculture Organization (FAO). Among the food items we
examined, cheese was most closely correlated with the
incidence of testicular cancer at ages 20-39, followed by
animal fats and milk. The correlation coefficient (r) was
highest (r
= .804) when calculated for cheese consumed during the period
= 1961-65 (maternal
or prepubertal consumption). Stepwise-multiple-regression
analysis revealed that milk + cheese (1961-65) made a
significant contribution to the incidence of testicular cancer
(standardized regression coefficient [R] = 0.654). Concerning
prostatic cancer, milk (1961-90) was most closely correlated
(r = 0.711) with its incidence, followed by meat and coffee.
Stepwise-multiple-regression analysis identified milk + cheese
as a factor contributing to the incidence of prostatic cancer
(R = 0.525). The food that was most closely correlated with
the mortality rate of prostatic cancer was milk (r = 0.766),
followed by coffee, cheese and animal fats.
Stepwise-multiple-regression analysis revealed that milk
+ cheese was a factor contributing to mortality from prostatic
cancer (R = .580). The results of our study suggest a role
of milk and dairy products in the development and growth of
testicular and prostatic cancers. The close correlation
between cheese and testicular cancer and between milk and
prostatic cancer suggests that further mechanistic studies
should be undertaken concerning the development of male
genital organ cancers. Copyright 2001 Wiley-Liss, Inc.

PMID: 11857417 [PubMed - in process]

[Paul Roger]

"Wuzzy" <mypcos@hotmail.com> wrote in message
news:d996c21a.0202261350.264cd2ef@posting.google.com...
> hi guys, this article is wicked to read in full..
>
> 1: Int J Cancer 2002 Mar 10;98(2):262-7
>
> Incidence and mortality of testicular and prostatic cancers
> in relation to
world
> dietary practices.
>
> Ganmaa D, Li XM, Wang J, Qin LQ, Wang PY, Sato A.
>
> Department of Environmental Health, Medical University of
> Yamanashi,
Tamaho,
> Yamanashi, Japan.
>
> The incidence and mortality rates of testicular and
> prostatic cancers in
42
> countries were correlated with the dietary practices in
> these countries
using
> the cancer rates (1988-92) provided by the International
> Agency for
Research on
> Cancer (IARC) and the food supply data (1961-90) provided by
> the Food and Agriculture Organization (FAO). Among the food
> items we examined, cheese
was
> most closely correlated with the incidence of testicular
> cancer at ages
20-39,
> followed by animal fats and milk. The correlation
> coefficient (r) was
highest (r
> = .804) when calculated for cheese consumed during the
> = period 1961-65
(maternal
> or prepubertal consumption). Stepwise-multiple-regression
> analysis
revealed that
> milk + cheese (1961-65) made a significant contribution to
> the incidence
of
> testicular cancer (standardized regression coefficient [R]
> = 0.654).
Concerning
> prostatic cancer, milk (1961-90) was most closely correlated
> (r = 0.711)
with
> its incidence, followed by meat and coffee.
> Stepwise-multiple-regression analysis identified milk +
> cheese as a factor contributing to the
incidence of
> prostatic cancer (R = 0.525). The food that was most closely
> correlated
with the
> mortality rate of prostatic cancer was milk (r = 0.766),
> followed by
coffee,
> cheese and animal fats. Stepwise-multiple-regression
> analysis revealed
that milk
> + cheese was a factor contributing to mortality from
> prostatic cancer (R = .580). The results of our study
> suggest a role of milk and dairy products
in
> the development and growth of testicular and prostatic
> cancers. The close correlation between cheese and testicular
> cancer and between milk and
prostatic
> cancer suggests that further mechanistic studies should be
> undertaken
concerning
> the development of male genital organ cancers. Copyright
> 2001 Wiley-Liss,
Inc.

Wuz,

Dairy products consistently show up as a risk factor for
prostate cancer. Other studies seem to show they may be
protective of colon and breast cancer -- not sure why, or if
the effect is real. (A possible confounder would be vitamin D
supplementation of milk.) The prostate connection with dairy
intake seems to be related to the suppression of vitamin D by
calcium, phosphorus and sulfur amino acids in dairy and meat.
Vitamin D (active D3) may well curb the growth and progression
of prostate and breast cancer.

IGF-1 probably plays a part as well.

This fits well with a recent study that showed sunbathing, or
at least ultraviolet radiation exposure, is correlated with a
reduced risk of prostate cancer. UV exposure provides a dose
of vitamin D. In addition, some studies show that fruit
consumption decreases prostate cancer risk. Fructose increases
vitamin D by altering calcium and phosphate balance. The
fructose in fruit could be protective for this reason. Meat
consumption also lowers vitamin D levels by lowering blood pH
with sulfur-containing amino acids.

So, perhaps the lesson from this is: for men at least, if you
eat a lot of dairy, eat it at the beach while snacking on the
local fruit.

Paul R

[Peter Fack]

Wuzzy -

that's confirming the correlation between milk/cheese and
prostate cancer (insuline growth factor IGF). I looked up some
sources relating to coffee but didn't find a strong linkage.
There is still the pushing of urinary problems.

Regards

Peter

In article <d996c21a.0202261350.264cd2ef@posting.google.com>,
mypcos@hotmail.com (Wuzzy) wrote:

>Concerning prostatic cancer, milk (1961-90) was most closely
>correlated
(r = 0.711) with its incidence, followed by meat and coffee.
>PMID: 11857417 [PubMed - in process]

[Quentin Gr]

This post not CC'd by email On 26 Feb 2002 13:50:11 -0800,
mypcos@hotmail.com (Wuzzy) wrote:

>The food that was most closely correlated with the mortality
>rate of prostatic cancer was milk (r = 0.766), followed by
>coffee, cheese and animal fats.

G'day G'day Wuzzy,

I find this result in the Japanese study fascinating. A USA
based study reached the opposite conclusion find coffee
protective. The basis for their argument was that prostate
cancer rates were inversely correlated with boron levels and
in the US diet coffee was, due to heavy consumption, a major
source of boron.

It is easy to see than in other countries where boron is
already adequately supplied from other sources, coffee would
not be protective.

Secondly it is also easy to see how the conclusion reached in
the US study might not be valid. While coffee contains some
boron it also contains a lot of other compounds. Conclusions
based on single factors have a habit of being wrong.

--
Quentin Grady ^ ^ / New Zealand, >#,#< [ / \ /\ "... and the
blind dog was leading."

http://homepages.paradise.net.nz/quentin

[Jay Tanzma]

Paul Rogers wrote:

> This fits well with a recent study that showed sunbathing,
> or at least ultraviolet radiation exposure, is correlated
> with a reduced risk of prostate cancer.

Unfortunately, you also increase your risk of skin cancer. It
seems you can't win. I wonder if you can even break even.

-Jay

[Quentin Gr]

This post not CC'd by email On Wed, 27 Feb 2002 06:59:57 GMT,
"Paul Rogers" <ecoldata@bigpond.net.au> wrote:

>The prostate connection with dairy intake seems to be related
>to the suppression of vitamin D by calcium, phosphorus and
>sulfur amino acids in dairy and meat. Vitamin D (active D3)
>may well curb the growth and progression of prostate and
>breast cancer.
>
>IGF-1 probably plays a part as well.

G'day G'day Paul,

The IGF-1 from cows milk gives rise to some interesting
speculation.

The anti-milk brigade make much of a report that bovine IGF is
identical to human IGF or at least close enough to avoid being
digested. According to them is a unique situation not repeated
else where.

If IGF is problem then one answer is to eat goat cheese as the
IGF of other animals differs sufficiently from that of humans
so is digested.

If active Vit D is the vital factor there might be something
to be said for eating free range chickens, herrings and
anchovies. Those who don't wish to risk exposure to the sun
could at least eat something that has seen the light of day.

--
Quentin Grady ^ ^ / New Zealand, >#,#< [ / \ /\ "... and the
blind dog was leading."

http://homepages.paradise.net.nz/quentin

[Paul Roger]

"Jay Tanzman" <jtanzman@sph.llu.edu> wrote in message
news:3C7D057E.6A2F69A4@sph.llu.edu...
>
>
> Paul Rogers wrote:
>
> > This fits well with a recent study that showed sunbathing,
> > or at least ultraviolet radiation exposure, is correlated
> > with a reduced risk of prostate cancer.
>
> Unfortunately, you also increase your risk of skin cancer.
> It seems you
can't
> win. I wonder if you can even break even.

Too true. The melanomas regularly get we beach goers over
here. Insidious things they are too. In rare cases they can
appear, metastasize then disappear, and you wonder where the
hell the primary is.

Trying to get my complement of selenium and carotenes just in
case they might be protective.

Cheers, Paul

[Matti Nark]

Wed, 27 Feb 2002 08:12:46 -0800 in article
<3C7D057E.6A2F69A4@sph.llu.edu> Jay Tanzman
<jtanzman@sph.llu.edu> wrote:
>
>Paul Rogers wrote:
>
>> This fits well with a recent study that showed sunbathing,
>> or at least ultraviolet radiation exposure, is correlated
>> with a reduced risk of prostate cancer.
>
>Unfortunately, you also increase your risk of skin cancer. It
>seems you can't win. I wonder if you can even break even.
>
Obviously malignant melanoma is the biggest worry, other skin
cancers are easily cured in most cases. It seems, however,
that sun exposure may have a dual effect on melanoma risk.
Ness et [1] have written IMHO an important article about
health effects of sun exposure. Among other things they refer
to the study by Elwood et al. [2]. An excerpt from
[4]:

"The main rationale for the health message - reduce
exposure to sunlight, and, in particular, avoid sunburn -
has been the belief that exposure contributes to the
increasing incidence of malignant melanoma.2 However, the
exact nature of the association between malignant
melanoma and exposure to sunlight has yet to be
determined.7 A recent systematic review of case-control
studies confirmed that intermittent sun exposure (odds
ratio 1.71; 95% confidence interval 1.54 to 1.90) and
sunburn at all ages (1.91;
5.69 to 2.17) were associated with an increased risk of
melanoma. It also showed, however, that people exposed
to sun through their work were at a reduced risk (0.86;
0.76 to 0.96).8 Even if reducing exposure to sunlight
reduces the incidence of melanoma, its effect on overall
mortality will be slight, as the number of deaths
postponed will be small. In 1995, the deaths of 697 men
and 698 women in England and Wales were attributed to
malignant melanoma.9 Even the most forceful campaign
could be expected to prevent only a few of these deaths.
There may also be effective options for reducing
mortality from melanoma that do not require reducing
exposure to sunlight - for example, by increasing
awareness of the diagnosis and access to treatment."

(references in the end of the article on the web page
http://bmj.com/cgi/content/full/319/7202/114 )

So the pattern of the sun exposure seems to affect the risk:
intermittent exposure and sunburn increase risk, but regular
exposure may actually reduce risk if sunburn is avoided. The
explanation may be vitamin D production stimulated by
exposure. Several studies suggest that vitamin D may have
anti-cancer effects via various mechanisms including
antiangiogenesis, anti-proliferative effects, induction of
apoptosis and induction of cell differentiation [3-10].
Intermittent exposure may not guarantee sufficient vitamin D
production, but may still damage the skin. Regular exposure
instead will help to maintain sufficient vitamin D level
needed for anti-melanoma effect. Vieth [16] and Vieth et al.
[18] mention that maximum daily dose (about 10000 - 20000 IU)
of vitamin D is produced in skin in about 20 minutes of full
body sun exposure (in light skinned people). After that the
balance is reached and no more vitamin D will become available
to our bodies. Therefore it seems that it's possible to "win",
if you 1) get _regular_ sun exposure, and 2) limit your daily
exposure to avoid damage to the skin - say to 20 minutes or
less of full body exposure. This of course applies only to
people living between 40th latitudes, people living outside
these latitudes cannot during winter get enough UVB-radiation
for cutaneous production of vitamin D.

As discussed here extensively in January, there are other
diseases such as auto-immune diseases including MS and type 1
diabetes, many other types of cancer, seasonal affective
disorder, osteoporosis, and even brain aging which may be
associated with vitamin D deficiency or insufficiency, which
seems much more prevalent than previously thought.

References:

6: Ness AR, Frankel SJ, Gunnell DJ, Smith GD. Are we really
dying for a tan? BMJ. 1999 Jul 10;319(7202):114-6. No
abstract available. PMID: 10398641 [PubMed - indexed for
MEDLINE] http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cm-
d=Retrieve&db=PubMed&list_uids=10398641&dopt=Abstract
http://bmj.com/cgi/content/full/319/7202/114

7: Elwood JM, Jopson J. Melanoma and sun exposure: an
overview of published studies. Int J Cancer. 1997 Oct
9;73(2):198-203. Review. PMID: 9335442 [PubMed - indexed
for MEDLINE] http://www.ncbi.nlm.nih.gov/entrez/query.fcg-
i?cmd=Retrieve&db=PubMed&list_uids=9335442&dopt=Abstract

8: Weinstock MA. Do sunscreens increase or decrease melanoma
risk: an epidemiologic evaluation. J Investig Dermatol
Symp Proc. 1999 Sep;4(1):97-100. Review. PMID: 10537017
[PubMed - indexed for MEDLINE] http://www.ncbi.nlm.nih.go-
v/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1053-
7017&dopt=Abstract

9: van den Bemd GJ, Pols HA, van Leeuwen JP. Anti-tumor
effects of 1,25-dihydroxyvitamin D3 and vitamin D analogs.
Curr Pharm Des. 2000 May;6(7):717-32. Review. PMID:
10828303 [PubMed - indexed for MEDLINE] http://www.ncbi.n-
lm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_-
uids=10828303&dopt=Abstract

10: Mantell DJ, Owens PE, Bundred NJ, Mawer EB, Canfield AE. 1
alpha,25-dihydroxyvitamin D(3) inhibits angiogenesis in
vitro and in
vivo.Circ Res. 2000 Aug 4;87(3):214-20. PMID: 10926872 [PubMed
- indexed for MEDLINE] http://www.ncbi.nlm.nih.gov/entre-
z/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10926872&d-
opt=Abstract

6: Majewski S, Kutner A, Jablonska S. Vitamin D analogs in
cutaneous malignancies. Curr Pharm Des. 2000
May;6(7):829-38. Review. PMID: 10928819 [PubMed - indexed
for MEDLINE] http://www.ncbi.nlm.nih.gov/entrez/query.fcg-
i?cmd=Retrieve&db=PubMed&list_uids=10928819&dopt=Abstract

7: Shokravi MT, Marcus DM, Alroy J, Egan K, Saornil MA,
Albert DM. Vitamin D inhibits angiogenesis in transgenic
murine retinoblastoma. Invest Ophthalmol Vis Sci. 1995
Jan;36(1):83-7. PMID: 7529753 [PubMed - indexed for
MEDLINE] http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cm-
d=Retrieve&db=PubMed&list_uids=7529753&dopt=Abstract

8: Danielsson C, Torma H, Vahlquist A, Carlberg C. Positive
and negative interaction of 1,25-dihydroxyvitamin D3 and
the retinoid CD437 in the induction of human melanoma cell
apoptosis. Int J Cancer. 1999 May 5;81(3):467-70. PMID:
10209963 [PubMed - indexed for MEDLINE] http://www.ncbi.n-
lm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_-
uids=10209963&dopt=Abstract

9: Danielsson C, Fehsel K, Polly P, Carlberg C. Differential
apoptotic response of human melanoma cells to 1
alpha,25-dihydroxyvitamin D3 and its analogues. Cell
Death Differ. 1998 Nov;5(11):946-52. PMID: 9846181
[PubMed - indexed for MEDLINE] http://www.ncbi.nlm.nih.g-
ov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=98-
46181&dopt=Abstract

10: Evans SR, Houghton AM, Schumaker L, Brenner RV, Buras RR,
Davoodi F, Nauta RJ, Shabahang M. Vitamin D receptor and
growth inhibition by 1,25-dihydroxyvitamin D3 in human
malignant melanoma cell lines. J Surg Res. 1996 Feb
15;61(1):127-33. PMID: 8769954 [PubMed - indexed for
MEDLINE] http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cm-
d=Retrieve&db=PubMed&list_uids=8769954&dopt=Abstract

11: Ainsleigh HG. Beneficial effects of sun exposure on cancer
mortality. Prev Med. 1993 Jan;22(1):132-40. Review. PMID:
8475009 [PubMed - indexed for MEDLINE] http://www.ncbi.nl-
m.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_u-
ids=8475009&dopt=Abstract

12: Garland FC, White MR, Garland CF, Shaw E, Gorham ED.
Occupational sunlight exposure and melanoma in the U.S.
Navy. Arch Environ Health. 1990 Sep-Oct;45(5):261-7. PMID:
2256710 [PubMed - indexed for MEDLINE] http://www.ncbi.nl-
m.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_u-
ids=2256710&dopt=Abstract

13: DeLuca HF, Ostrem V. The relationship between the vitamin
D system and cancer. Adv Exp Med Biol. 1986;206:413-29.
PMID: 3035900 [PubMed - indexed for MEDLINE] http://www.n-
cbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&-
list_uids=3035900&dopt=Abstract

14: Colston K, Colston MJ, Fieldsteel AH, Feldman D.
1,25-dihydroxyvitamin D3 receptors in human epithelial
cancer cell lines. Cancer Res. 1982 Mar;42(3):856-9. PMID:
6895862 [PubMed - indexed for MEDLINE] http://www.ncbi.nl-
m.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_u-
ids=6895862&dopt=Abstract

15: Frampton RJ, Suva LJ, Eisman JA, Findlay DM, Moore GE,
Moseley JM, Martin TJ. Presence of 1,25-dihydroxyvitamin
D3 receptors in established human cancer cell lines in
culture. Cancer Res. 1982 Mar;42(3):1116-9. PMID: 6277475
[PubMed - indexed for MEDLINE] http://www.ncbi.nlm.nih.go-
v/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6277-
475&dopt=Abstract

16: Vieth R. Vitamin D supplementation, 25-hydroxyvitamin D
concentrations, and safety. Am J Clin Nutr. 1999
May;69(5):842-56. Review. http://www.ncbi.nlm.nih.gov/ent-
rez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10232622&-
dopt=Abstract
http://www.ajcn.org/cgi/content/abstract/69/5/842
http://www.ajcn.org/cgi/content/full/69/5/842 (free)
http://www.ajcn.org/cgi/reprint/69/5/842.pdf

17: Robert P Heaney Lessons for nutritional science from
vitamin D American Journal of Clinical Nutrition, Vol. 69,
No. 5, 825-826, May 1999
http://www.ajcn.org/cgi/content/full/69/5/825 (free)

18: Vieth, R., Chan, P.-C. R, MacFarlane, G. D (2001).
Efficacy and safety of vitamin D3 intake exceeding the
lowest observed adverse effect level. Am. J. Clin. Nutr.
73: 288-294 http://www.ncbi.nlm.nih.gov/entrez/query.fcgi-
?cmd=retrieve&db=pubmed&list_uids=11157326&dopt=Abstract
http://www.ajcn.org/cgi/content/abstract/73/2/288
http://www.ajcn.org/cgi/content/full/73/2/288
http://www.ajcn.org/cgi/reprint/73/2/288.pdf


-Matti Narkia

[Paul Roger]

"Paul Rogers" <ecoldata@bigpond.net.au> wrote in message
news:tQcf8.14904$RV3.67999@news-server.bigpond.net.au...
> "Jay Tanzman" <jtanzman@sph.llu.edu> wrote in message
> news:3C7D057E.6A2F69A4@sph.llu.edu...
> >
> >
> > Paul Rogers wrote:
> >
> > > This fits well with a recent study that showed
> > > sunbathing, or at least ultraviolet radiation exposure,
> > > is correlated with a reduced risk of prostate cancer.
> >
> > Unfortunately, you also increase your risk of skin cancer.
> > It seems you
> can't
> > win. I wonder if you can even break even.
>
> Too true. The melanomas regularly get we beach goers over
> here. Insidious things they are too. In rare cases they can
> appear, metastasize then disappear, and you wonder where the
> hell the primary is.
>
> Trying to get my complement of selenium and carotenes just
> in case they might be protective.

The other paradox that occurred to me is that melanoma is one
of the fastest growing and most dangerous cancers and prostate
is one of the slowest growing (usually). C'est la vie.

PR

[Matti Nark]

Wed, 27 Feb 2002 22:11:37 GMT in article
<tQcf8.14904$RV3.67999@news-server.bigpond.net.au> "Paul
Rogers" <ecoldata@bigpond.net.au> wrote:
>
>Too true. The melanomas regularly get we beach goers over
>here. Insidious things they are too. In rare cases they can
>appear, metastasize then disappear, and you wonder where the
>hell the primary is.
>
>Trying to get my complement of selenium and carotenes just in
>case they might be protective.
>
If my memory serves me correctly, other substances which may
be of benefit include green tea and green tea extracts (also
topical products are emerging) and COX-2 inhibitors (COX-2 is
induced in the skin damaged by sun and it may play role in the
carcinogenesis; there are also herbal COX inhibitors). Olive
oil applied topically _after_ sun exposure also seems to have
protective or healing effect.

-Matti Narkia

[Paul Roger]

"Matti Narkia" <mnng@surfeu.fi> wrote in message
news:qsqq7us598ofdongh2peforeko0eep1tmf@4ax.com...
> Wed, 27 Feb 2002 08:12:46 -0800 in article
> <3C7D057E.6A2F69A4@sph.llu.edu> Jay Tanzman
> <jtanzman@sph.llu.edu> wrote:
> >
> >Paul Rogers wrote:
> >
> >> This fits well with a recent study that showed
> >> sunbathing, or at least ultraviolet radiation exposure,
> >> is correlated with a reduced risk of prostate cancer.
> >
> >Unfortunately, you also increase your risk of skin cancer.
> >It seems you
can't
> >win. I wonder if you can even break even.
> >
> Obviously malignant melanoma is the biggest worry, other
> skin cancers are easily cured in most cases. It seems,
> however, that sun exposure may have a dual effect on
> melanoma risk. Ness et [1] have written IMHO an important
> article about health effects of sun exposure. Among other
> things they refer to the study by Elwood et al. [2]. An
> excerpt from
> [1]:
>
> "The main rationale for the health message - reduce
> exposure to sunlight, and, in particular, avoid sunburn
> - has been the belief that exposure contributes to the
> increasing incidence of malignant melanoma.2 However,
> the exact nature of the association between malignant
> melanoma and exposure to sunlight has yet to be
> determined.7 A recent systematic review of case-control
> studies confirmed that intermittent sun exposure (odds
> ratio 1.71; 95% confidence interval 1.54 to 1.90) and
> sunburn at all ages (1.91;
> 1.69 to 2.17) were associated with an increased risk of
> melanoma. It also showed, however, that people exposed
> to sun through their work were at a reduced risk
> (0.86; 0.76 to 0.96).8 Even if reducing exposure to
> sunlight reduces the incidence of melanoma, its effect
> on overall mortality will be slight, as the number of
> deaths postponed will be small. In 1995, the deaths of
> 697 men and 698 women in England and Wales were
> attributed to malignant melanoma.9 Even the most
> forceful campaign could be expected to prevent only a
> few of these deaths. There may also be effective
> options for reducing mortality from melanoma that do
> not require reducing exposure to sunlight - for
> example, by increasing awareness of the diagnosis and
> access to treatment."
>
> (references in the end of the article on the web page
> http://bmj.com/cgi/content/full/319/7202/114 )
>
> So the pattern of the sun exposure seems to affect the
> risk: intermittent exposure and sunburn increase risk, but
> regular exposure may actually reduce risk if sunburn is
> avoided. The explanation may be vitamin D production
> stimulated by exposure. Several studies suggest that
> vitamin D may have anti-cancer effects via various
> mechanisms including antiangiogenesis, anti-proliferative
> effects, induction of apoptosis and induction of cell
> differentiation [3-10]. Intermittent exposure may not
> guarantee sufficient vitamin D production, but may still
> damage the skin. Regular exposure instead will help to
> maintain sufficient vitamin D level needed for
> anti-melanoma effect. Vieth [16] and Vieth et al. [18]
> mention that maximum daily dose (about 10000 - 20000 IU) of
> vitamin D is produced in skin in about 20 minutes of full
> body sun exposure (in light skinned people). After that the
> balance is reached and no more vitamin D will become
> available to our bodies. Therefore it seems that it's
> possible to "win", if you 1) get _regular_ sun exposure,
> and 2) limit your daily exposure to avoid damage to the
> skin - say to 20 minutes or less of full body exposure.
> This of course applies only to people living between 40th
> latitudes, people living outside these latitudes cannot
> during winter get enough UVB-radiation for cutaneous
> production of vitamin D.

Matti, I have been aware of this paradox for some time. In the
sub-tropics here it is virtually compulsory for children to
wear hats at school -- not a bad thing -- and the message
"slip, slop, slap" about wearing protective clothing and
sunscreen is an icon of our culture. However, what I dread is
these children getting to fifteen or sixteen, being more
independent, shooting off the the beach all day with mates,
and, not ever having had a more than a drop of sun all their
lives, getting severe sunburn. It happens.

Much more appropriate, I feel, to give children gradual,
modest exposure from early years to protect them to some
extent against the harsher times to come. Within our beach and
sporting culture, sun exposure is unavoidable. What we don't
want to do, in my view, is get the 'shock' burns that sow the
seeds for melanoma and SCCs later in life. Skin types are
relevant of course. There is also the issue of UV and immune
system modulation.

However, as you point out, perhaps there is a nice point on
the dose-response curve that gives maximum benefit. The guys
surfing ten hours/day are probably not interested in the 20
minutes though <g>.

Cheers, Paul R

[Jay Tanzma]

Matti Narkia wrote:

> things they refer to the study by Elwood et al. [2]. An
> excerpt from
> [1]:
>
> "... A recent systematic review of case-control studies
> confirmed that intermittent sun exposure (odds ratio
> 1.71; 95% confidence interval 1.54 to 1.90) and sunburn
> at all ages (1.91;
> 1.69 to 2.17) were associated with an increased risk of
> melanoma. It also showed, however, that people exposed
> to sun through their work were at a reduced risk
> (0.86; 0.76 to 0.96)."

I question whether a review of case-control studies could
"confirm" these relationships. Case-control studies are
subject to serious selection and recall biases; the latter,
especially when case subjects are aware of the hypothesis
being investigated, as melanoma patients likely would be if
they were being asked about their history of sun exposure.
Meta-analyses of case-control studies can be misleading
because all the studies in the analysis can suffer from the
same biases, and the resulting combined odds ratio can be
highly statistically significant (as it is in the quoted
study), but utterly invalid.

-Jay

[Steve Harr]

Jay Tanzman wrote in message
<3C7E9AD4.DBA89569@sph.llu.edu>...
>
>
>Matti Narkia wrote:
>
>> things they refer to the study by Elwood et al. [2]. An
>> excerpt from
>> [1]:
>>
>> "... A recent systematic review of case-control studies
>> confirmed that intermittent sun exposure (odds ratio
>> 1.71; 95% confidence interval 1.54 to 1.90) and sunburn
>> at all ages (1.91;
>> 1.69 to 2.17) were associated with an increased risk of
>> melanoma. It also showed, however, that people
>> exposed to sun through their work were at a reduced
>> risk (0.86; 0.76 to 0.96)."
>
>I question whether a review of case-control studies could
>"confirm" these
relationships. Case-control
>studies are subject to serious selection and recall biases;
>the latter,
especially when case subjects are
>aware of the hypothesis being investigated, as melanoma
>patients likely
would be if they were being asked
>about their history of sun exposure. Meta-analyses of
>case-control studies
can be misleading because all
>the studies in the analysis can suffer from the same
>biases, and the
resulting combined odds ratio can be
>highly statistically significant (as it is in the quoted
>study), but
utterly invalid.

Yep, right on.

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