Medical updates

MEDICAL UPDATE
Is there a link between ovarian cancer and using talcum powder?

Following a recent TV programme suggesting that women should not use talcum powder on the genital area owing to an increased risk of ovarian cancer, Ovacome has asked Adam Rosenthal and Ian Jacobs to prepare a brief summary of the evidence in order to clarify the situation

Dr Adam Rosenthal is a research fellow in the Gynaecology Cancer Research Unit at St. Bartholomew's Hospital. Ian Jacobs is a Consultant Gynaecological Oncologist and Director of the Gynaecology Cancer Research Unit at St. Bartholomew's Hospital

The most convincing evidence linking use of talc on the genital area with ovarian cancer is based on interviewing women with and without ovarian cancer and asking them if they have used talc.

So far there have been nine of these studies (called "case-control studies"). Only two showed a significant risk associated with talc use. Another five revealed a small increase in risk which was not statistically significant.

A minority of studies examined the use of talc on the lower abdomen, but it is even harder to draw conclusions about the risk associated with this practice due to the design of the studies.

Even if the risk of ovarian cancer is increased, it is at most doubled by using talc on the genital area. Although doubling the risk of ovarian cancer may sound frightening, to put it into context combined smoking and drinking increase the risk of another rare cancer, oesophageal cancer, over 30-fold. So as ovarian cancer is a rare disease, doubling a very small risk still gives a very small risk.

There are a number of doubts and concerns about the design and results of these studies:

• Only one of the three studies which tried to see if the amount of talc used increased the risk showed a slight increase in risk the more talc was used. This is strange, as other cancer risks are related to exposure to the risk factor, e.g. the more you smoke, the more likely you are to get lung cancer. If talc really does cause ovarian cancer, why didn't all the studies show that the risk of ovarian cancer was related to the amount of talc used?
• It could be that talc does not cause ovarian cancer, but that women who use talc are also exposed to another risk which we do not yet know about.
• Case-control studies of this type can suffer from bias which can lead to inaccurate results. For example, women with ovarian cancer understandably seek a cause for their disease and may have been more likely to remember using talc than those who did not have cancer.
• Assuming that the different groups of women studied are the same "type" of person may cloud the issue. For example, it might be that women with ovarian cancer who use talc are more likely to answer a questionnaire than those who do not use talc. This would bias the results so that it appeared that most women with ovarian cancer had used talc even though only a minority actually did so.
• Not all the women in the studies answered all the questions, so conclusions may have been based on incomplete information.

The other evidence of concern comes from studies which have shown the presence of talc within the ovaries of women with ovarian cancer. There is also doubt about the significance of these studies:

• Not all studies excluded the possibility that the talc came from the protective gloves worn by the scientists examining the ovaries, rather than from talc applied to the genital area.
• The numbers of ovaries studied was very small.
• Talc was found in normal ovaries as well as cancerous ones.
• Finding talc in an ovarian cancer is not the same as proving that the talc caused the cancer.

We still do not know what really causes ovarian cancer, but it is likely to be a combination of inherited and environmental factors, rather than one single agent such as talc.

We do know that women who become pregnant or take the oral contraceptive pill are at considerably lower risk of developing ovarian cancer and this beneficial effect is proved much more convincingly than the link between talc and ovarian cancer.

We also know that women with two or more close relatives with ovarian cancer or breast cancer may be at increased risk of developing ovarian cancer. The issue of familial ovarian cancer risk will be covered in the next Ovacome newsletter.

It is also important to keep in mind the fact that, out of the millions of women in England and Wales many of whom use talc, only a very small proportion will develop ovarian cancer each year. So even if talc does increase the risk slightly, very few women who use talc will ever get ovarian cancer. In addition if someone has ovarian cancer and used talc, it seems highly unlikely that use of the talc was the reason they developed the cancer.

Further studies will be needed to work out exactly what role, if any, talc use plays in ovarian cancer.

Screening for Ovarian Cancer

Ovacome has received a large number of enquiries about screening for ovarian cancer and familial ovarian cancer. In this article Karen Sibley and Ian Jacobs have summarised the current situation.

Karen Sibley RGN, BSc is a Nursing Sister and Project Manager of the St Bartholomew's Hospital Ovarian Cancer Screening Study.

Ian Jacobs MD, MRCOG is a Consultant Gynaecological Oncologist and Director of the Gynaecology Cancer Research Unit at St Bartholomew's Hospital.

Why may screening for ovarian cancer be important?
Early-stage ovarian cancer confined to the ovaries (Stage I) has an extremely good outlook and can be successfully treated. Unfortunately most ovarian cancers are not recognised at an early stage for a number of reasons.

First, cancer of the ovary usually develops after the menopause when the ovaries are inactive and abnormal function of the ovary is not therefore readily noticed.

Second, the ovaries are located deep inside the pelvis and are inacessible to examination.

Finally, even when symptoms do occur they are usually vague, non-specific symptoms which could be due to a host of other causes.

So by the time most women with ovarian cancer develop symptoms and their cancer is detected, it has spread outside the ovaries to the pelvis (Stage II), the abdomen (Stage III) or more distant sites (Stage IV) and is far more difficult to treat successfully. This information has long suggested that an effective method of screening to detect early-stage ovarian cancer might save the lives of many women.

What screening tests are available?
Three potential methods of screening for ovarian cancer have been assessed:

Internal examination
Also called pelvic or bimanual examination, can be performed to identify enlarged ovaries. Although internal examination can detect large ovarian tumours, even experienced doctors are not able to reliably detect ovarian cancer at an early stage. Internal examination is not regarded as an effective method for early detection of ovarian cancer.

CA 125 blood test
CA125 is a protein released into the circulation in high levels in most women with ovarian cancer. The CA 125 test is frequently used to diagnose ovarian cancer in women who have symptoms and to monitor women after and during treatment of ovarian cancer. It is important to recognise that CA 125 is also produced by many normal tissues and levels in the bloodstream can therefore also be raised in normal situations (e.g. pregnancy, menstruation) and benign conditions as well as ovarian cancer. The CA 125 test is easily and quickly performed on a small blood sample sent to the laboratory.

Ultrasound
Ultrasound scanning is the same technique as is used in pregnancy and can be used to visualise the size and texture of the ovaries. Ultrasound scans can be performed either by placing a probe on the abdomen or by inserting a probe into the vagina.

In ovarian cancer the ovaries increase in size and the texture becomes abnormal due to formation of cysts and solid growths. Unfortunately, some of these abnormal features also occur in benign ovarian tumours and other conditions in the pelvis. So, as with CA 125 it is important to realise that ultrasound results can be abnormal even when there is no cancer present.

How effective are the screening tests?

There is no doubt that screening can detect ovarian cancer early.
A number of large-scale studies have been performed to look at the possibility of using either CA125 or ultrasound to screen for ovarian cancer. Two of the largest studies of screening for ovarian cancer have been performed in the UK.

The King's College Study investigated the role of ultrasound in over 5000 women and demonstrated that ultrasound can detect many cases of ovarian cancer at an early stage.

The Royal London/St. Bartholomew's Hospital Study assessed the use of CA 125 in combination with ultrasound in 22,000 women. This study revealed that it was possible to detect many cases of ovarian cancer before any symptoms developed.

However, it is uncertain whether screening actually saves lives from ovarian cancer.
Although screening with CA 125 and/or ultrasound can detect ovarian cancer early, this does not necessarily mean that screening will save lives.

It is possible that, even though screening detects cancer early, this would not be early enough to make a difference. Screening is only worthwhile if it detects ovarian cancer sufficiently early to make treatment more effective.

Large studies are in progress at present to determine whether screening saves lives (see below), but at present it is unclear whether or not screening saves the lives of women who develop ovarian cancer.

What are the problems with screening for ovarian cancer?

False positive results are common.
The major problem with screening for ovarian cancer is that both the CA 125 test and ultrasound scanning can be abnormal in a proportion of women who do not have cancer of the ovary. These sorts of results, known as 'false positives', are a serious problem as they can cause a great deal of anxiety. Even worse, if the abnormalities persist, it may ultimately be necessary to perform an operation to exclude the possibility of ovarian cancer which turns out to have been unnecessary.

As ovarian cancer is relatively uncommon, more abnormal screening results are due to false positive findings than are due to cancer.

False negative results can occur.
Most women find a normal screening result reassuring. However, neither CA 125 nor ultrasound will pick up every case of ovarian cancer. 'False negative' results do occur and a small number of women will be falsely reassured.

What studies are in progress?

Studies of women in the general population.
There are two very large studies in progress to determine whether screening with ultrasound or CA 125 saves lives. In order to get a definitive answer to this question both these studies need to involve approximately 120,000 women, of which 60,000 will be screened and the other 60,000 observed.

One of these studies is organised from St. Bartholomew's Hospital and uses CA125 as an initial test followed by ultrasound for women with abnormal CA 125 levels. Women over 50 years of age who have reached the menopause and have no family history or a weak family history of ovarian cancer (no more than one affected relative) can volunteer for this study by writing to The Ovarian Cancer Screening Project, St. Bartholomew's Hospital, London EC1A 7BE.

The other study uses ultrasound as the main screening test and is organised at specific centres in the UK and Europe.

The UKCCCR Familial Ovarian Cancer Screening Study.
A national study has just been launched to assess and refine screening amongst women with a strong family history of ovarian cancer.

A strong family history means two or more close relatives with ovarian cancer or one relative with ovarian cancer and a relative with breast cancer which occurred at a young age (<50 years).

Women who think they fall into this category should ask their GP for advice and may be referred to a specialist genetics centre for the family history to be confirmed. Most regional genetics centres will know how to enrol eligible women into the familial screening study, which involves an annual CA 125 test and ultrasound scan.

What should YOU do about ovarian cancer screening?
Many women are concerned about their risk of developing ovarian cancer, particularly if they have a friend or relative who has developed the cancer. It is understandable that many women with this first-hand experience of ovarian cancer wish to be screened.

There is no absolutely right or wrong advice about screening but it is important to be aware of the limitations and disadvantages of current screening techniques. Broad guidelines are provided below but the decision made by an individual woman will understandably be heavily influenced by her experience of ovarian cancer.

Women under 50 with no family history
The risk of ovarian cancer to women less than 50 years of age is small and the risk of a false positive screening result is high. Screening is not recommended for this group of women.

Women over 50 with no family history
There is at present no evidence that screening is of value to women in this age group and there are definite disadvantages. For this reason routine screening is not recommended. Women in this group may, however, volunteer to participate in one of the ongoing general population screening trials mentioned above.

Women with a weak family history
Many women in this group have one close relative who has developed ovarian cancer and are understandably anxious about their own risk. The risk to women in this group is slightly, but not greatly, increased and the value of screening is uncertain. Some centres do offer advice and counselling to women with a weak family history. Ultimately the decision about screening must be an individual one after a careful explanation of the pros and cons. Women with a weak family history are eligible for the general population screening trials.

Women with a strong family history
Women with a strong family history are at substantially increased risk of ovarian cancer and may wish to participate in the National Familial Ovarian Cancer Screening Study. This group of women should have access to expert advice about prevention as well as screening through referral to a specialist centre. They may then be offered participation in the National Familial Ovarian Cancer Screening Study.

More detailed information about familial ovarian cancer will be provided in the next Ovacome newsletter.