Breast cancer is the most common potentially fatal cancer of women in the Western world. After lung cancer, breast cancer was the second leading cause of cancer death in women in Ireland between 2007 and 2009, accounting for 16 per cent of cancer deaths. However, thanks to major advances in treatment, survival rates for women with breast cancer in Ireland today continue to increase significantly. There are about 2,500 cases of breast cancer diagnosed in Ireland every year and the disease predominantly affects middle-aged and older women.
CAUSES
A woman’s risk of developing breast cancer increases the older she gets. A small minority of breast cancers are genetic or caused by an inherited gene. However, most women who develop breast cancer do not have a particularly strong family history of the disease. In fact, for the majority of women who get breast cancer, there is no particular identifying feature.
The single biggest set of factors that determine susceptibility in societies to breast cancer is associated with affluence. In societies where people eat more and children tend to be healthier, girls reach puberty at younger ages and the menopause occurs later. All of these things increase the number of monthly menstrual cycles, each one of which gives a surge of oestrogen, which, in turn, increases the risk of breast cancer.
Women who have more children at a younger age have a slightly lower incidence of breast cancer while those who have fewer children at an older age have a somewhat higher incidence of the disease.
There does seem to be a correlation between alcohol intake and an increased risk of developing breast cancer and there is definitely a link between obesity and increased risk. To reduce the number of deaths from breast cancer in the future, it needs to be tackled on three different fronts: prevention, early diagnosis and treatment. In relation to prevention, the single biggest thing we can do is to combat obesity.
SIGNS AND SYMPTOMS
The most common sign of breast cancer is a painless lump in the breast. It can also present as a swelling in the breast or a change in the shape of the breast, for example, a change in the shape of the nipple. Notwithstanding this, an increasing number of women are diagnosed with breast cancer having had no symptoms as a result of breast screening.
In Ireland, all women between the ages of 50 and 64 are entitled to a free breast-screening cancer test or mammogram as part of BreastCheck, the National Breast Screening Programme.
The evidence is reasonably clear that there is a benefit associated with breast-screening, although it has a relatively modest impact. Many women are screened to save one life. For an individual patient, the difference it makes in terms of her chances of living or dying is relatively small, but from a societal point of view it is a means by which we will reduce the number of deaths from breast cancer.
DIAGNOSIS
A negative mammogram does not mean that a woman who presents with a breast lump does not have cancer.
A woman who presents with a lump or changes in the breast needs a proper medical evaluation by her GP. If the GP is worried that the lesion might be cancer, the mere fact that they have a negative mammogram is not adequate. The GP should refer the woman to a breast specialist. He or she will do a mammogram, a clinical examination and an ultrasound and the lump may need to be biopsied.
PREVENTION AND TREATMENT
One of the many fears that women understandably express when they are diagnosed with breast cancer is that they will need a mastectomy – an operation to have their breast removed, but the good news is that for the vast majority of women nowadays that is no longer the case. While it is not unheard of for a woman with early-stage disease to have her breast removed, it is uncommon. For most women, it is possible to preserve the breast with a smaller operation.
The good news is that the majority of women who present with relatively early stage disease are potentially curable. While it may not be possible to cure every single woman, they are all treated with what is called curative intent. This means that the various tests carried out show no evidence of spread to any other parts of the body and as a result the treatment is relatively intensive with a view to eradicating the cancer completely.
In the great majority of cases, treatment will involve some surgery and it may also include radiotherapy, particularly in those women who have not had a full mastectomy.
Some women may also need additional therapy, known as adjuvant therapy, such as chemotherapy or hormone therapy.
The reason for giving adjuvant therapy, such as chemotherapy, is that even if tests show that the cancer has not spread, we know that some of these patients will develop secondary or metastatic cancer. In these cases, the cancer has spread and it could not be detected with currently available technologies.
However, thanks to a test called the Oncotype DX Test we can now predict whether or not a woman will need this additional chemotherapy to fully eradicate the cancer from her system. It is thanks to the work of the Irish Co-operative Oncology Research Group (ICORG) that this test is widely available in Ireland.
The most widely used and probably most effective breast cancer drug in the world in terms of saving lives is a drug called Tamoxifen.
The first person to give Tamoxifen to patients as part of a clinical trial in the early 1960s was an Irish doctor called Mary Patricia (Moya) Cole, who was originally from Cavan. Dr Cole is the great unsung heroine of Irish cancer research. She carried out the most influential piece of work ever done by an Irish cancer researcher, which has probably saved more than a million lives worldwide.
There have been some real advances in breast cancer treatment in recent years, the biggest of which was the discovery that it is not a case of one size fits all.
The discovery that breast cancer is a complex set of diseases that behave differently in individual patients has led to the development of tailored treatments for specific types of breast cancer.
For example, one of the original tailored treatments to be developed was the drug Herceptin. This drug acts on a particular molecule, HER2, that is over-expressed in a specific sub-type of breast cancer known as HER2 positive breast cancer. Herceptin has made a big difference in terms of improving the prognosis of patients with this particular type of cancer.
Ireland, again through ICORG, had a modest but important contributory role in helping to develop Herceptin – we got involved in the research early on and, as a result, Irish patients were among the first in the world to receive the drug.
In summary, the news is good for breast cancer, with both the number of deaths and new cases decreasing.
The take-home message for women is that if they want to decrease their risk of getting breast cancer they should try and reduce their alcohol intake and be careful about their weight. Any woman who is worried about a lump or a change in her breast should see her GP and all women over 50 should attend for regular breast screening.
USEFUL RESOURCES
[ www.icorg.ieOpens in new window ]
BreastCheck, www.breastcheck.ie
Irish Cancer Society, www.cancer.ie
Prof John Crown is a consultant oncologist and a member of the Irish Co-operative Oncology Research Group (ICORG)