TALC

Linda enjoying another baby

Talc is in the news; Johnson & Johnson has been ordered by a jury to pay $72 million to the family of a woman who died at 62 of ovarian cancer.  She was a longtime user of talcum powder, and her suit contends that this was the cause of her disease.  Needless to say, J & J is appealing.  $72 million is pocket change to J & J; clearly they are fighting to retain a profitable product.  They will do so if they can demonstrate that talc is safe, presumably by means of clinical trials.  So, job opportunities galore for statistically minded biologists.  In the meantime; what to think?

I have written about talc and lawsuits before: http://ljb-quiltcutie.blogspot.com/2015/05/of-torts-and-talcum-powder.html.

So what is talc, anyway?  Chemically it is a hydrous magnesium silicate, formed from common magnesium-bearing minerals such as olivine, pyroxene and serpentine by metamorphism in the presence of water and carbon dioxide.  It is the softest natural mineral.  It usually occurs in extremely small grains, often in the company of asbestos.  It is a principal component of soapstone.  And, it often can be found in small containers next to piles of diapers.

Well, we all know that asbestos can cause lung cancer, but it appears that asbestos is not central to this issue because asbestos in talc has been sought out and eliminated since the 1970s.  However, asbestos remains an element in the dispute: asbestos is deadly because of its small grain size; it can lodge in the lung and cause genetic changes that lead to cancer.  Well, talc also forms tiny grains; could these tiny grains lodge in ovarian epithelium, cause genetic changes, etc.?  What is needed is scientific proof – principally in the form of clinical trials.  And here is where things get ugly.

Glossary:

Case-control study:  A study which matches individuals who have a condition with another, as like as possible, who does not have the condition.  This is a retrospective study: subjects are asked to think back and report how often and how intensely did they do something-or-other, such as smoke cigarettes or use talcum powder.

Recall bias:  The likelihood that people with the disease are more likely to report the activity under study than those who are free of the condition.  I explain it badly, but you get the point.

Cohort studies:  These are prospective.  A cohort is formed (for instance, all women named Alice born in New Jersey in 1948).  This cohort reports periodically on the thing under study – talcum powder use, for instance. After a suitably long time the statisticians are summoned to see if there is a “robust” correlation that MIGHT reflect cause and effect.  Recall bias is eliminated in cohort studies, rendering this approach more reliable.

So what do these studies indicate?  One researcher cited avers that the case is closed and has been for some time: 20 well-executed case control studies published over the last 30 years agree that talc usage is associated with increased incidence of ovarian cancer, by as much as 30%.  Recall bias is cited by some, but dismissed with considerable scorn by others.  To me it is noteworthy that there is a positive “dose response” in talc use: the more you use, the worse your odds.  Case closed, huh?

But wait.  Two recent cohort studies have shown no significant correlation with use of talc and ovarian cancer.  These were based on very large data bases, and presumably conducted properly.  So what the heck?

It may be significant that the scientist quoted has derived part of his income from Johnson & Johnson, but obviously he didn’t make the whole thing up.

Well, how might talc cause ovarian cancer?  As suggested earlier, maybe tiny talc grains become lodged in the ovary (or fallopian tubes) and cause long-term, localized inflammation, resulting in cancer.  Nobody has shown that this happens, but then – nobody has tried.  It is significant that many autopsies find talc grains where they should not be, including in ovarian tumor tissue.  

So what is the bottom line?  You guessed it: MORE RESEARCH IS NEEDED (!)  Experts disagree.  The American Cancer Society “calls for more research” and states that “if there is an increased risk it is likely to be small”.  30%, in my book,  is not small.

In the meantime, you can bet your prized collection of talcum powder dispensers that J&J is conducting a massive cover-your butt operation. If they knew that their product was not entirely safe and did nothing about it then they deserve their fate: bankruptcy.

Apparently there is a corn starch product that can sub for talcum powder.  Why not use it?