By Charles Bankhead, Staff Writer, MedPage Today
April 07, 2011
Use of talc-based powder significantly increased the risk of invasive ovarian cancer in a large case-control study that confirmed other analyses performed over the past 30 years.
Overall, talc use increased ovarian cancer risk by about 30%; however, the risk increased by two- to threefold among women reporting long-term frequent application of talc powder to the genital area, as reported here at the American Association for Cancer Research.
"I have always advised gynecologists, if they examine a woman and see that she is using talc in the vaginal area, tell her to stop," said Daniel W. Cramer, MD, of Brigham and Women's Hospital in Boston. "There are alternatives. This study strongly reinforces that advice."
Results of more than 20 epidemiologic studies have supported an association between application of talc-based powder to the external genitalia and ovarian cancer, but the findings have met with considerable skepticism and criticism, in part, because of a lack of evidence for a dose-response effect, said Cramer.
The biologic plausibility of the association also has been questioned. Cramer previously hypothesized that talc had an effect on cancer risk similar to that of asbestos. More recently, he has come to believe that the association involves upregulation of heat-shock proteins, mucins, and other molecules that predispose to chronic inflammation.
Inadequate cleansing after use of talc, particularly frequent use, might allow the powder to migrate into the lower genital tract and initiate an inflammatory reaction, Cramer speculates.
Talc particles have been found in lymph nodes and other tissues of ovarian cancer patients, he added.
In an effort to resolve the uncertainty surrounding the talc-ovarian cancer association, Cramer and his colleagues analyzed data from a case-control study involving more than 2,000 women with ovarian cancer and a similar number of women without the cancer.
All study participants resided in New Hampshire and eastern Massachusetts. History of talc use had a reference date of one year before diagnosis for the ovarian cancer patients and use at the date of interview for the control group.
Logistic regression analysis examined the association between ovarian cancer and regular use of genital talc and from the perspective of total number of talc applications, estimated from patient-reported frequency and duration of use.
The investigators adjusted for age, parity, oral contraceptive use, tubal ligation, body mass index, smoking, alcohol use, Jewish ethnicity, and family history of breast or ovarian cancer.
They performed separate analyses for all cases, nonmuscinous invasive cancer, serous invasive cancer, and serous invasive cancer unlikely to be familial.
For all analyses, talc use was associated with an increased prevalence of ovarian cancer; the magnitude of the difference between users and nonusers ranged between 20% and 40%, most often about 30%.
None of the analyses yielded significant differences among premenopausal women.
All analyses produced statistically significant differences for all study participants and for the subgroup of postmenopausal women, who accounted for 60% of the study participants.
Adjustment for clinical, demographic, and histologic factors had minimal impact in analyses of the overall population or the postmenopausal subgroup.
For example, analysis of all histologic subtypes yielded a hazard ratio of 1.30 in all participants (P=0.0003) and 1.31 for postmenopausal women (P=0.003).
Analysis of serous invasive cancer by menopausal status and after exclusion of women with Jewish ethnicity and family history of cancer resulted in odds ratios of 1.39 (P=0.001) and 1.35 (P=0.01) for all participants and postmenopausal women, respectively.
Analysis of dose-response associations by total applications (quartiles of none to ¡Ý8,400) showed a significant trend for all women (P=0.002), premenopausal women (P=0.05), and postmenopausal women (P=0.02).
The trend held up in most of the analyses by histologic subtype and by differences in demographic and clinical variables.
The significant trend for dose-response effect persisted whether women reporting no talc use were excluded or included (P=0.001).
"Menopausal status has a striking effect on the dose-response for the association," said Cramer. "Premenopausal women with frequent use may have more than a threefold increase in their risk for invasive serous cancer of the ovary. Repeating these analyses in existing data sets may help clarify the association between talc and ovarian cancer."
Cramer told MedPage Today that the association between talc and ovarian cancer has led to a lawsuit against talc manufacturers by a woman in South Dakota. Depositions are expected to begin later this year.
The plaintiff's attorney previously represented patients with mesothelioma in successful lawsuits and settlements involving asbestos manufacturers, Cramer added.
The study was supported by the National Cancer Institute.
Cramer had no relevant disclosures.
Primary source: American Association for Cancer Research
Vitonis AF, et al "Talc use and ovarian cancer: Influence of histologic type and menopausal status on strength and dose-response of the association" AACR 2011; Abstract LB-446.
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