Οι άνδρες που δεν είναι γόνιμοι κινδυνεύουν περισσότερο από καρκίνο – Men with low sperm production face increased cancer risk

p00sjl0n

Οι άνδρες που δεν είναι γόνιμοι, επειδή πάσχουν από έλλειψη σπερματοζωαρίων στο σπέρμα τους (αζωοσπερμία), κινδυνεύουν περισσότερο να αναπτύξουν καρκίνο, σύμφωνα με μια νέα αμερικανική επιστημονική έρευνα. Αν μάλιστα η διάγνωση γίνει πριν την ηλικία των 30 ετών, τότε ο κίνδυνος είναι οκταπλάσιος.

Οι ερευνητές, με επικεφαλής τον καθηγητή ουρολογίας Μάικλ Άιζενμπεργκ της Ιατρικής Σχολής του πανεπιστημίου Στάνφορντ της Καλιφόρνιας, που έκαναν τη σχετική δημοσίευση στο περιοδικό για θέματα γονιμότητας και στειρότητας “Fertility and Sterility”, μελέτησαν τις περιπτώσεις 2.238 μη γόνιμων ανδρών με μέση ηλικία 36 ετών, από τους οποίους οι 451 εμφάνιζαν αζωοσπερμία.

Η μελέτη έδειξε ότι γενικώς οι άνδρες με πρόβλημα γονιμότητας (όχι κατ’ ανάγκη με έλλειψη σπερματοζωαρίων) έχουν 1,7 φορές μεγαλύτερη πιθανότητα να εμφανίσουν καρκίνο σε σχέση με τον γενικό πληθυσμό.

Stanford-School-of-Medicine-logo

Men who are diagnosed as azoospermic — infertile because of an absence of sperm
in their ejaculate — are more prone to developing cancer than the general
population, a study led by a Stanford
University School of Medicine
urologist has found. A diagnosis of
azoospermia before age 30 carries an eight-fold cancer risk, the study
says.

“An azoospermic man’s risk for developing cancer is similar to that
for a typical man 10 years older,” said Michael
Eisenberg
, MD, PhD, assistant professor of urology at the medical school and
director of male reproductive medicine and surgery at Stanford Hospital & Clinics.
Eisenberg is lead author of the study, published online June 20 in Fertility
and Sterility
.

Diagnoses of male infertility and azoospermia are
surprisingly common in the United States. About 4 million American men — 15
percent of those ages 15-45 — are infertile. Of these, some 600,000 are
azoospermic. “There is evidence that infertility may be a barometer for men’s
overall health,” Eisenberg said, “and a few studies have found an association of
male infertility with testicular cancer.” The new study, he said, not only
assigns the bulk of infertile men’s increased cancer risk to those with
azoospermia, but also suggests that this risk extends beyond testicular
cancer.

Eisenberg conducted most of the analysis for the study at
Stanford, using data gathered from the Texas Cancer Registry and the Baylor College of Medicine in Houston, where he
completed his medical training. The study’s senior authors are Larry Lipshultz, MD,
and Dolores Lamb,
PhD, professors of urology at Baylor.

The study population consisted of
2,238 infertile men who were seen at a Baylor andrology clinic from 1989 to
2009. Their median age was 35.7 when they were first evaluated for the cause of
their infertility. Of those men, 451 had azoospermia, and 1,787 did not. There
were otherwise no apparent initial differences between the two groups.

Azoospermia can arise for two reasons. Obstructive azoospermia is caused by a
blockage that prevents otherwise plentiful, fit sperm produced in the testes
from reaching the ejaculate. But a screen of about one-fourth of the azoospermic
men in the study population indicated that the vast majority suffered from the
nonobstructive variety: Their testes didn’t produce enough sperm for any to
reach their ejaculate, most likely because of genetic deficiencies of one sort
or another. Fully one-fourth of all the genes in the human genome play some role
in reproduction, Eisenberg noted, so there are a lot of ways for the capacity to
sire offspring to go astray.

After undergoing a semen analysis, the men were followed for an average of 6.7
years to see which of them turned up in the Texas Cancer Registry. (Fortunately
for the analysis, most people tend to stay in the state where they’ve grown up,
said Eisenberg.) Their rates of diagnosed cancer incidence were then compared
with age-adjusted cancer-diagnosis statistics of Texas men in general.

In
all, a total of 29 of the 2,238 infertile men developed cancer over a 5.8-year
average period from their semen analysis to their cancer diagnosis. This
contrasted with an expected 16.7 cases, on an age-adjusted basis, for the male
Texas population in general (which, Eisenberg said, closely reflects cancer
incidence rates for the entire U.S. population). This meant that infertile men
were 1.7 times as likely to develop cancer as men in the general population.
This is considered a moderately increased risk.

But comparing the cancer
risk of azoospermic and nonazoospermic infertile men revealed a major disparity:
The azoospermic men were at a substantially elevated risk — nearly three times
as likely to receive a diagnosis of cancer as men in the overall population.
Infertile men who weren’t azoospermic, in contrast, exhibited a statistically
insignificant increased cancer risk of only 1.4 times that of men in the overall
population.

By excluding men whose cancer diagnosis came within two or
three years of their infertility evaluation, the researchers were able to rule
out the possibility that azoospermia caused by an undiagnosed cancer had
affected the statistics.

While the study wasn’t large enough to delineate
which specific types of cancer pushed azoospermic men’s incidence rates up, the
diagnoses they received covered a wide range of cancers: brain, prostate and
stomach tumors, as well as melanoma, lymphoma, testicular cancer and cancer of
the small intestine. The findings suggest that genetic defects that result in
azoospermia may also broadly increase a man’s vulnerability to cancer, Eisenberg
said, supporting the notion that azoospermia and cancer vulnerability may share
common genetic causes.

The study, which was funded by the National Institute for Child Health and Human
Development
, is the first to examine the cancer risk of azoospermia in
particular and to link it to non-germ-cell cancers. Previous studies have failed
to consistently identify any increased risk for nontesticular cancers in
infertile men, whether azoospermic or otherwise. In those previous studies,
however, azoospermic men couldn’t be separately examined because sperm analyses
weren’t available.

Most striking of all, said Eisenberg, was the cancer
risk among azoospermic men who first had their semen analyzed before age 30.
They were more than eight times as likely to subsequently develop cancer than
Texas males in the general population of the same age. In contrast, there was no
relationship between age of semen analysis and risk of cancer for nonazoospermic
men.

The good news, Eisenberg said, is that while the cancer risk among
young azoospermic men was quite large compared to their same-age peers, their
relative youth means that their absolute risk of contracting cancer during the
follow-up period remained small. The bad news, he said, is that men in their 30s
often don’t have a primary health-care provider. He advised that young men who
are diagnosed as azoospermic should be aware of their heightened risk and make
sure to get periodic checkups with that in mind.

Information about Stanford’s Department of Urology, which also supported this
work, is available at http://urology.stanford.edu.

Source

Read also:

Τυφλοπόντικας με ανοσία στον καρκίνο δίνει ελπίδες και για τους ανθρώπους – Naked mole rat gives cancer clues

Αναγνώριση της παχυσαρκίας ως ασθένεια στις ΗΠΑ – Obesity now recognized as a disease

Γεννήθηκε το εκατομμυριοστό βρέφος χωρίς AIDS στην Αφρική – Working Toward an AIDS-Free Generation

Φταίνε οι άνδρες για την γυναικεία εμμηνόπαυση; – Why men are to blame for women’s menopause

4 Responses

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: