Breast cancer

Breast cancer

Breast cancer is the most common cancer in women in Australia1 and the second most common cancer to cause death in women, after lung cancer. It is uncommon in males.

Incidence and mortality

In 2011, 14,465 women and 103 men were diagnosed with breast cancer in Australia. The risk of being diagnosed with breast cancer by age 85 is 1 in 8 for women and 1 in 917 for men.

In 2012, 2795 women and 24 men died of breast cancer in Australia.

Screening

Mammographic screening every two years is recommended for women aged 50-74 years, though it is available to women from 40 years of age. Younger women in high risk groups may be screened by Magnetic Resonance Imaging (MRI).

Symptoms and diagnosis

Symptoms include:

new lumps or thickening in the breast or under the arm

nipple sores

nipple discharge or turning in

skin of the breast dimpling

rash or red swollen breasts.

Pain is rare.

Diagnosis is usually by imaging eg. mammogram, then biopsy by needling or removing the lump.

Staging

Staging involves assessing the size of the breast cancer and whether it has spread to the draining lymph nodes under the arm. A CT scan of the chest and liver and bone scan are done to check the sites to which breast cancers most commonly spread.

Causes

The causes of breast cancer are unknown, but risk factors include:

increasing age

family history

inheritance of mutations in the genes BRCA2, BRCA1 and CHEK2

exposure to female hormones (natural and administered)

obesity (poor diet and inadequate exercise) and

excess alcohol consumption.

There is also an association with some benign breast disease and past exposure to radiation.

Prevention

There is no proven method of prevention, however women who are at high risk because of a very strong family history may benefit from hormones such as tamoxifen, usually administered over five years. Bilateral prophylactic mastectomy can be considered in women at high risk of breast cancer due to gene mutations.

Treatment 

Treatment depends on the extent of the cancer.

For localised breast cancer, the most extensive surgical option is to remove the breast and lymph nodes under the arm. However, removing the lump and just a section of the breast, followed by radiotherapy, results in the same rate of survival. If the first draining lymph node can be identified using dye or a nuclear medicine scan, it can be sampled and if it is negative, further surgery avoided.

For tumours at greater risk of recurrence ie. bigger, more aggressive cancers, or cancers that have spread to the lymph nodes, additional treatment (adjuvant therapy) can be given after surgery. This can include hormone therapy of aromatase inhibitors or tamoxifen for women whose tumours have hormone receptors on their surfaces, and chemotherapy and targeted therapies such as trastuzumab for those 25% of tumours that are HER2 positive (ie. have the target for trastuzumab on their surfaces).

Patients presenting with locally extensive cancer will have chemotherapy and radiotherapy initially to see if it will shrink the cancer to make it operable.

If breast cancer returns after initial treatment, local disease may be treated with surgery, while more widespread disease will be treated with combinations of similar drugs to those used in adjuvant treatment. Common chemotherapy drugs include anthracyclines and taxanes.

Patients with bone disease can receive bisphosphonates such as zoledronate to slow the erosion of bones, and receive local radiotherapy for pain.

Prognosis

An individual's prognosis depends on the type and stage of cancer as well as their age and general health at the time of diagnosis. If the cancer is limited to the breast, 96% of patients will be alive five years after diagnosis; this figure excludes those who die from other diseases. If the cancer has spread to the regional lymph nodes, five year relative survival drops to 80%. In Australia, the overall five year survival rate for breast cancer is 89%.

For more information, contact Cancer Council 13 11 20 (cost of a local call).

1)

Excluding non-melanoma skin cancer, which is the most commonly diagnosed cancer according to general practice and hospitals data, however there is no reporting of cases to cancer registries.

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