Saturday, February 25, 2017

The Ovarian Cancer-Talc Lawsuit Genesis


Class-action lawsuits were making America Great Again long before it was a thing.  Attorneys actively solicit anyone involved (or maybe might be potentially involved) in a particular event, and get them all in one place to file a chunky lawsuit.  

This gives a little fuel to the lawsuit for obvious reasons, and is appealing to the “victim(s)” because they do not have to shop out an attorney, and they get to commune with others that were also “victimized”.  All they have to do is sit back and collect the check.  

While it seems like a possible lottery ticket based on the marketing from the commercials, this is rarely a windfall for the consumers, and mostly the attorneys profit while the defendants get a check in the mail that would barely buy a dozen doughnuts. 
Recently a wide net has been cast for class action lawsuits trying to fish out women who sprinkled baby powder down their bloomers.   The connection between cosmetic talc and ovarian cancer is not obvious, and a good subject for A Look Deeper. 
How could baby powder induce a problem in the ovary?  That’s one anatomical gem tucked pretty far out of harm’s way.  Someone must have been doing something really wrong!
To explore the basis of this non-intuitive association I explored the peer-reviewed literature and found an especially informative review on the subject (Muscat and Huncharek, 2008). Here I’ll review their review for the purpose of providing some backstory to the curious television legal solicitation.
The story begins with talc, a silicate compound, and a cousin of asbestos.  Asbestos has been known to be a lung carcinogen, and in 1978 a survey of talc-containing powders found cancer-causing silicates in about 50% of commercial talc powders.  While these were thought to be potentially problematic for lung cancers, there was no concern about other uses. Cosmetic talcs cleaned up after that.
The connection to ovaries starts with perineal dusting.  Sounds like the name of a righteous rock band, or perhaps what I pay the cleaning lady to do, but it is the practice of applying talc to the perineum.  In case you forgot, you should know the perineum from childhood as the low spot on our baby doll’s torso where they’d put a hole for drainage or air expansion.  The undercarriage.  Apparently a dusting of talc was present on many feminine products or added as a cooling powder to undergarments during daily wear.  So at least the silicate compound was getting into the right neighborhood.
Still no concern to anybody until 1982.  A case-control (retrospective, survey-based) study on ovarian cancer patients revealed a slightly higher than normal association between the disease and perineal dusting. Complicating matters, it is never clear which products used this way actually contain talc.  On top of that, the authors propose that the personal nature of perineal dusting could also affect the responses of those responding. Not everyone wants to admit to powdering their parts. Once again you can always find correlation with no causation, and many times that is enough to cause mass hysteria.
The rather loose association was sufficient to ignite the news media at the time, and for decades to follow this connection stewed in the back ground of cancer causes. Then in 2006 the International Agency for Research on Cancer promoted perineal talc use as a “probable carcinogen”, using its extremely conservative interpretations of available evidence.
There is no compelling direct mechanism proposed. Unlike asbestos, talc is not fibrous, and it is known to not be genotoxic. Hypotheses revolving around inflammation and even induction of specific antibodies have been proposed, but consistent supportive evidence is lacking, and indirect evidence is not pointing to these mechanisms.
The other question regards how the external genital dusting migrates up the genital tract, through the vagina and cervix, across the uterus and fallopian tubes, to the ovaries. Such journeys defy gravity and the known flow of mucous which favors an external direction. Still, there is no question that talc particles have been detected in some cancerous ovaries. Others detected no evidence of ovarian talc in known perineal dusters, and found talc in ovaries of non-dusters. It was also considered possible that the particles could go to the ovaries via inhalation. Talc on condoms and diaphragms was also considered, but no associations were observed.
This last observation is of particular importance.  There is no evidence to support the hypothesis that talc leads to cancer in relation to birth control devices that were treated with talc for years.  No relationship was seen between cervical or uterine cancer.  These findings indicate no associations when the alleged induction agent is placed directly into the genital canal. 
Occupational exposure in talc factories showed no higher incidence of lung or female reproductive cancers, and animal studies also showed similar outcomes.
The authors conclude that the data do not support the causal association between talc-based powders and ovarian cancer.  They conclude that the data are not sufficient to draw the conclusion.  On the other side, there may be genetic components and predispositions that could lead to carcinogenic potential in specific patients.
Based on this review of the literature the commercial for the class-action lawsuit seems to be based on rather tenuous evidence.  The lack of dose-response data, the fact that there are no associations with cervical or uterine cancers, and the fact that talc-dosed birth control had so association either. This appears to be another case where lawyers were effective in swaying a jury with less-than-conclusive science.
  
Muscat JE,Huncharek MS. Perineal Talc Use and Ovarian Cancer: A Critical Review. European journal of cancer prevention : the official journal of the European Cancer Prevention Organisation (ECP). 2008;17(2):139-146. doi:10.1097/CEJ.0b013e32811080ef.