As a GP I see many women who are concerned about potential breast and gynaecological cancers. A routine contraceptive pill prescription or hormone replacement therapy check can frequently lead to a discussion on cancer risk.
It is now possible to predict our genetic predisposition to many conditions. A recent Harvard study examined gene mutations in breast cancer cells that were responsible for a lack of response to anthracycline chemotherapy. This could pave the way for tailor-made treatments for cancer sufferers.
It is less clear, however, whether we should advocate diagnostic genetic testing in healthy people, unless they are at high risk. The National Institute for Clinical Excellence (Nice) has recommended genetic testing for conditions such as breast cancer, where the lifetime risk is one in three or higher, based on family history of breast and ovarian cancers. On average, the lifetime risk is one in nine.
I am increasingly being asked about gene faults that increase the chance of acquiring breast cancer, but there is less awareness of gene mutations being associated with ovarian cancer, which is just as important. Women should consider discussing this, too, with their GP.
Cancers arise from abnormalities in cell DNA causing them to grow and spread. The causes of these genetic "errors" are often multi-factorial and include exposure to carcinogens, hormonal influences or our inherited genes.
According to Cancer Research UK, there are 7,000 cases of ovarian cancer diagnosed every year. In women this is now the fourth most common cancer after breast, lung and bowel cancers. But while the death rates for other cancers have fallen steadily over the years, those for ovarian cancer have not. It is more prevalent in women who have been through the menopause, with eight out of 10 cases being diagnosed after the age of 50. One reason for this is that as we get older we accumulate more errors in our genes, which can have a cumulative effect along with other risk factors. Survival rates are higher in younger women, where they can be in excess of 70 per cent.
Inherited gene mutations account for less than 10 per cent of all ovarian cancers and around 5 per cent of breast cancers. While the lifetime risk of a woman developing ovarian cancer is 1-2 per cent, for women with one close relative who has had the disease (for instance their mother or sister), this rises to 3-5 per cent, and may be as high as 40 per cent with two or more affected relatives.
Women with mutations of Breast Cancer Susceptibility Gene 1 and 2 (BRCA 1/2) – which belong to a class of genes called tumour suppressors and are responsible for preventing uncontrolled cell growth and maintaining healthy DNA – have a 50-80 per cent lifetime risk of acquiring breast cancer and a 15-40 per cent risk of ovarian cancer. Men with BRCA mutations also have an increased risk of getting breast cancer. However, not all family members will have these inherited mutations.
The aim of genetic screening in at-risk individuals is to quantify their risk and provide information on potential additional cancers that are linked to the same mutations, such as those of the bowel, pancreas and in men, the prostate. It will also guide medical surveillance, so that if mutations have been detected then appropriate cancer screening can be offered. Surveillance includes annual scans and/or blood tests.
Patients who have cancer can have genetic testing for BRCA mutations, as this may help screen other family members. Individuals without cancer – but with a strong family history of breast and ovarian cancer – can also be referred for testing. Counselling is usually recommended and includes a discussion of medical and family histories, testing methods and implications of positive and negative results. A blood sample is needed from a relative with a history of cancer, and if a gene fault is identified then other relatives can be tested for the same fault. This is known as predictive testing.
However, this only provides information about our risk, rather than telling us whether or not we will develop cancer.
Women who are shown to be at high risk are offered yearly checks to detect for early signs of the disease, when it would be most treatable. Removal of healthy fallopian tubes and ovaries can possibly reduce the risk of developing breast (in pre-menopausal women) and ovarian cancer in some women. However, this major surgery has its own risks, such as early menopause if carried out in younger women. There have also been instances of related cancers in some women despite early preventive surgery.
Genetic screening remains an evolving and highly specialised area of medicine. When coupled with appropriate education and counselling it can provide useful information, either to allay or confirm our fears. Negative results can give a sense of relief to women and avoid unnecessary interventions. Positive results can lead many women to make informed decisions about their futures and take steps to minimise their risk.
However, the question of when to test is often as important as whether to test at all. It can affect people's decisions on marriage and childbearing or create tension between relatives. Issues of privacy and confidentiality arise, particularly when some family members do not wish to disclose their results to relatives.
People who receive a positive result may feel anxious, depressed or angry. They may choose to postpone having children or undergo preventive measures such as prophylactic ovarian surgery, which in turn may prevent future pregnancies. Those with negative results could be left with "survivor" guilt, knowing that their loved ones are affected. It is an intensely personal and complex decision that I myself would find very difficult. But it is important to address this uncertainty and fear of the future, which is faced by many women and their families.
source: telegraph
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