July 13, 2018

expert reaction to talc and ovarian cancer, re US court decision on Johnson & Johnson paying damages

Johnson & Johnson has been ordered to pay $4.7bn (£3.6bn) in damages to 22 women who claimed that its talc products caused them to develop ovarian cancer.

Prof Paul Pharoah, Professor of Cancer Epidemiology, University of Cambridge, said:

“In my view the decision of the court is flawed for two reasons.  First, while it is clear that there is an association between genital talc use and ovarian cancer risk association does not mean causation.  The evidence that the association is causal is very weak.  Second, even if the association were true, the strength of the association is too small to be able to say on the balance of probabilities that any cancer arising in a woman who used talc had been caused by the talc.

“Around 7,000 women are diagnosed with ovarian cancer in the UK each year.  This makes ovarian cancer the 5th most common cancer in women, after breast, lung, bowel and womb cancer.  Not all ovarian cancer is the same.  There are several different types of ovarian cancer – high-grade serous, endometrioid, clear cell and mucinous being the main ones – and these have different risk factors and clinical features.

“The main risk factors for ovarian cancer are hormone replacement therapy use, being overweight, and having endometriosis.  Smoking is associated with one of the rarer types of ovarian cancer – mucinous ovarian cancer.  There are several genetic variants that are associated with an increased risk.  Faults in the BRCA1 and BRCA2 genes in particular are associated with high risks.

“The use of the oral contraceptive pill during early adulthood is associated with a 50 per cent reduction in risk of ovarian cancer that persists many years after stopping the pill.  Pregnancy and breast feeding are also associated with a reduction in risk, as is tubal ligation (a form of sterilisation commonly referred to as having the tubes tied).

“A possible association between talcum powder use and risk of ovarian cancer has been reported for many years.  This association was based on case-control studies, which are rather prone to bias.  Prospective studies are less prone to bias than case-control studies, though they are not bias free.  There have been two prospective studies investigating this association.  One found a significant association with risk of the serous type of cancer, and the other found a non-significant increase in risk of the serous type of ovarian cancer.  An analysis pooling the results from all the available studies found that talc use was associated with a 30 per cent increase in risk (I emphasise that this association may not be causal).  There was no difference in the risk of the different types of ovarian cancer, which might be expected if the association were causal, and there was no clear increase in risk for women who used talcum power more often or for a longer time – a dose response – that would be expected if the association were causal.

“The association is biologically plausible, in that talcum powder applied to the genital area might get into the fallopian tubes and onto the ovaries and cause inflammation, which in turn could cause ovarian cancer – however as I’ve said there’s no strong evidence of that yet.

“It’s important to remember the size of the possible risk – a 20 year old woman in the UK has a risk of getting ovarian cancer at some point in her life of 18 in a thousand; a 30% increase in this risk would raise this to 23 in a thousand (assuming that the association were real).  A woman with a fault in the BRCA1 gene has a lifetime risk of ovarian cancer of about 400 in a thousand.”

Prof Paul Pharoah, Professor of Cancer Epidemiology, University of Cambridge, said:

“This verdict seems to be flawed.  Evidence from multiple epidemiological studies have demonstrated an association between perineal talcum powder use and subsequent risk of ovarian cancer – however, association is not the same as causation and several strands of evidence suggest that the association is not causal.  Furthermore, even if the association were causal (and I emphasis that this is not likely), the probability that previous talcum power use was actually a cause in a women with ovarian cancer is small.”

Declared interests

Prof Paul Pharoah: “I have acted as a paid expert to Shook Hardy Bacon, one of the law firms representing Johnson & Johnson.”