Some ovarian cancers are caused by inherited genetic mutations (for example, BRCA1/2, HNPCC) (see ‘Family history and genetics’). However, the cause of most ovarian cancer is unknown. Many women we interviewed had heard that it seems to be more common in women who have not had children and less common among those who have used oral contraception. Some wondered whether this was connected to the number of menstrual cycles a woman has in her life.

Stimulation of the ovary by the drugs used during infertility treatment is also known to slightly increase the risk of developing ovarian cancer. Women who had such treatment had asked their doctors about this.

Some women wondered whether hormone replacement therapy (HRT) could have increased their chances of developing ovarian cancer. Others asked whether events in their gynaecological history (such as ectopic pregnancy, tubal surgery, endometriosis or untreated ovarian cysts) could have had an effect. A woman regretted not having her ovaries removed when she had her hysterectomy some years before her ovarian cancer developed.

Many women talked about having had stressful episodes in their lives before their cancer diagnosis. Some believed this had been a possible cause, whilst others were not convinced since stressful life events happen to everyone. One woman felt that it wasn’t the stress itself that caused her problems but her tendency to become angry in many situations. Some women felt that stress could have been a contributory rather than a direct cause, for instance it could have been the final trigger in a series of events needed for cancer to develop, or it could have made them tired and run down leaving their immune system vulnerable to attack.

Several women believed that cancer was caused by a combination of factors such as family history, lifestyle and a trigger such as a virus or stress. One woman described this as like the line-up of three cherries on a fruit machine. A few suspected that an illness (for example a virus, ME, pleurisy) had weakened their immune systems, or could have been an, as yet unknown, bacterial or viral cause of ovarian cancer. Other ideas of possible causes included deodorants, environmental pollution, radiation, genetic mutations, poverty and poor diet in childhood and ‘everything from talcum powder to yoghurt’.

Other women wondered whether unhealthy aspects of their lifestyle may have been a factor, such as smoking, the Western diet, or being overweight. However, women who said they had lived a healthy life, or did not have any of the known risk factors, sometimes felt cheated because it hadn’t stopped them getting cancer. A woman who did not think that ovarian cancer was associated with any particular lifestyle said that at least she did not need to feel guilty because there wasn’t anything she should have done to avoid it.