The long-standing issue of the connection between talc and ovarian cancer recently came to a head following a jury award, in St Louis in the United States.
A multinational company was ordered to pay US$72mil (RM295.2mil) in damages to the family of a woman who had been a long-time user of the company’s talc powder, and who died of ovarian cancer (talc was found in her surgically-removed ovaries).
What about talc?
Talcum powder is made from talc, which consists of magnesium, silicon and oxygen.
The powder absorbs moisture and helps to reduce friction, keeping the skin dry and helping to prevent rashes.
It is widely used in cosmetic products like baby powder, adult body and facial powders, and other consumer products.
Some talc, in its natural form, contains asbestos, a known cause of lung cancer.
All household talcum products in the US have been asbestos-free since the 1970s.
The focus of the concerns about a possible link between talc and cancer is whether women who apply talc regularly in the genital area have an increased risk of ovarian cancer.
The basis of possible carcinogenicity is often attributed to chronic inflammation of the ovarian epithelium, due to contact with talc particles.
Very small particles comparable in size to talc have been shown to migrate from the vagina to the upper genital tract.
British surgeons reported in 1971 that a majority of ovarian tumours had talc particles deeply embedded in the tumour tissue. Talc has also been found in pelvic lymph nodes.
The first study to link talc with ovarian cancer was published in 1982.
Since then, there have been several case-control studies that support the link between talc use and ovarian cancer.
A case-control study is a study that is often used to identify risk factors for a condition.
The study compares a group of patients who have the condition with a group of patients who do not have it, and looks back in time at the differences between the two groups.
The latest study, which was quoted in the St Louis trial, reported a 33% increased risk of ovarian cancer in talc users (Epidemiology, published online Dec 17, 2015).
The risk for epithelial ovarian cancers from genital talc use varied by type of cancer, menopausal status at diagnosis, hormone therapy use, weight and smoking.
The talc/epithelial ovarian cancer link was largely confined to pre- and post-menopausal women who used hormone therapy.
The study had significant limitations and was unable to prove direct cause and effect. It reported that “subjects were interviewed about potential ovarian cancer risk factors more than one year before diagnosis”.
There is a possibility that the recall of talc use was inaccurate, leading to misclassification.
The study also could not determine whether talc use or ovarian cancer occurred first.
Although the researchers attempted to control for confounding factors, there was the possibility that these factors were not fully accounted for and others may have been missed.
In contrast, two large prospective, cohort studies published in the last 15 years reported no link between talc use and increased risk of ovarian cancer.
The studies used data from the Nurse’s Health Study and the Women’s Health Initiative (WHI), respectively (J Natl Cancer Inst 2000; 92: 249-52 and J Natl Cancer Inst 2014;106).
Prospective studies identify a group of people (cohort) and follow them up over a period of time to determine how their exposures affected their outcomes.
If carried out properly, prospective cohort studies are more authoritative than case-control studies, which are retrospective.
The WHI and the Nurse’s Health Study, however, had significant limitations that limited their value.
The WHI only collected information on the duration of use, not on frequency, while the Nurses’ Health Study only collected information on frequency of use, not on duration, with neither study providing a sufficient assessment of talc exposure.
The International Agency for Research on Cancer, a specialised agency of the World Health Organization, classifies the “perineal (genital) use of talc-based body powder as possibly carcinogenic to humans”.
The American Cancer Society (ACS), in its 2014 report, calls for more research and states “if there is an increased risk, the overall increase is likely to be very small”.
Currently, there have been mixed results from studies assessing the link between talc and ovarian cancer.
A 2014 editorial in the Journal of the National Cancer Institute stated: “While reporting bias may explain the positive associations reported from case-control studies, the limitations of the cohort studies regarding exposure assessment still do not completely eliminate the possibility that talc use is associated with ovarian cancer risk (JNCI J Natl Cancer Inst  106 (9): dju260).
In plain language, talc use might be a risk, and it also might not be.
The advice from the ACS is: “It is not clear if consumer products containing talcum powder increase cancer risk. Studies of personal use of talcum powder have had mixed results, although there is some suggestion of a possible increase in ovarian cancer risk. There is very little evidence at this time that any other forms of cancer are linked with consumer use of talcum powder.
“Until more information is available, people concerned about using talcum powder may want to avoid or limit their use of consumer products that contain it. For example, they may want to consider using cornstarch-based cosmetic products instead. There is no evidence at this time linking cornstarch powders with any form of cancer.”
It is pertinent to remember that gynaecologists recommend using plain, unperfumed soaps to wash the genital area daily, and not talc or perfumed soaps, gels and antiseptics.
Dr Milton Lum is a member of the board of Medical Defence Malaysia. The views expressed do not represent that of any organisation the writer is associated with. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.