NEW YORK, Mar 08 (Reuters Health) -- Factors that cause inflammation in the
lining of the ovaries -- such as endometriosis, or even powdering with talc --
increase the risk of ovarian cancer, according to researchers at the University
of Pittsburgh, Pennsylvania.
But the team also reports that gynecologic surgery, such as the female
sterilization procedure tubal ligation, greatly reduces a woman's risk of
developing the cancer.
In a study of more than 2,000 women aged 20 to 69, investigators found that
those with a history of endometriosis, ovarian cysts, or overactive thyroid were
at increased risk for ovarian cancer. Talc use, which may spur inflammation in
the ovarian lining, also elevated cancer risk. A team led by Roberta B. Ness, of
the Graduate School of Public Health, reports the findings in the March issue of
Epidemiology.
Certain factors that suppress ovulation and hormones that affect the ovaries
-- such as pregnancy, birth control pill use, and breastfeeding -- have widely
been found to protect against ovarian cancer. Yet the risk related to ovarian
inflammation is less well understood, according to Ness and her colleagues.
Inflammation, they note, produces toxic oxidants that inflict genetic damage in
cells, a process that may lead to cell changes and cancer.
In interviews with women with and without ovarian cancer, the study authors
found that, as expected, pregnancy and breastfeeding reduced cancer risk. In
addition, the team found a 50% decrease in risk with a first pregnancy and small
dips with each subsequent pregnancy. Oral contraceptives also lowered cancer
risk when used for at least one year.
The Pittsburgh researchers then questioned the women on factors that can
trigger ovarian inflammation. Three medical conditions were found to increase
cancer risk, relative to women without the conditions: ovarian cysts, growths on
the ovaries that can be harmless or dangerous, increased cancer risk by 30%; a
70% higher risk was linked to endometriosis, a condition in which pieces of the
uterine lining grow outside of the uterus; and hyperthyroidism, a disorder
marked by overproduction of thyroid hormones, was linked to an 80% higher risk
of ovarian cancer.
Both endometriosis and ovarian cysts may trigger local inflammation, and
both have been linked to ovarian cancer in previous studies, Ness and colleagues
note. This study is the first, however, to connect hyperthyroidism and ovarian
cancer. Hyperthyroidism, the researchers explain, often results from the immune
system's assault on the thyroid gland; such autoimmune diseases are systemic and
can trigger widespread inflammation.
As in numerous other studies, women who used talc anywhere on their bodies
or in their underwear showed an elevated cancer risk, even when risk factors
such as family history of ovarian cancer were considered.
One condition that causes ovarian inflammation, pelvic inflammatory disease,
was linked to only a slight incline in cancer risk. Other studies, the authors
note, have shown a stronger link.
Having had a hysterectomy or a tubal ligation helped protect women from
ovarian cancer. These procedures, the researchers explain, cut off the path
between the lower and upper genital tract, blocking inflammatory substances from
gaining access to the ovarian lining.
