By Dr. Gilian Wharfe, Contributor
CHEMOTHERAPY IS a form of systemic treatment for breast cancer. It has been recognised that many breast cancer patients who appear to be disease free after local (surgery) and regional (radiotherapy) treatment will eventually have recurrence of their disease and die of or with this problem.
It suggests, therefore, that although all visible disease has been treated, there is microscopic disease elsewhere in the body and this remains untreated and eventually grows. There is evidence that treatment of this hidden, microscopic disease may result in elimination of these cells and so prevent recurrence. The benefits of these treatments have been demonstrated in large studies which show improvement in survival with systemic treatment for breast cancer although for the majority of patients it does not provide a cure.
Chemotherapy treatments can be considered as adjuvant (treatment given with surgery and/or radiotherapy to treat potential microscopic disease) or palliative (treatment given to patients with advanced cancer to improve symptoms related to advanced cancer).
ADJUVANT CHEMOTHERAPY
Preoperative - neoadjuvant. This may be offered to patients with advanced (large) tumours which are localised. This may cause the tumour to become smaller and allow the surgeon to do less aggressive surgery.
Post operative chemotherapy - adjuvant. This is done after the patient has had wound healing (usually one month) after surgery. This treatment prevents recurrence of the cancer in about one third of patients and reduces the death rate by about 25 per cent compared with surgery alone. In patients with positive lymph nodes 10-year survival is improved from 50 to 60 per cent and for node negative disease from 75 to 80 per cent. A number of combinations of chemotherapy drugs can be offered, in most cases resulting in treatment continuing for four to six months. The choice of treatment used is based on features of the tumour and number of involved lymph nodes (lymph nodes with cancer).
PALLIATIVE CHEMOTHERAPY
This is used in patients who have obvious metastatic disease, that is, disease which has involved other sites apart from the breast. These include lungs, bones, liver, skin and brain. Chemotherapy is only one option for care in these patients. Other options include hormonal therapy and radiation therapy. It does not result in cure for these patients. The median survival time for these patients is approximately two years but some patients will die within a short time of disease recurrence whilst others may last for many years.
The goals of treatment include relief or palliation of symptoms whilst still maintaining a good quality of life. Patients with rapidly progressing disease are usually offered chemotherapy as first line as hormonal treatment responses may be slower and less likely in aggressive disease.
About 40 to 60 per cent of patients with metastatic disease will respond to chemotherapy although significantly less will have a complete response. It takes on average about two to three months to see a response. The duration of this response will be determined by a number of factors. These include the site of metastasis, number of previous treatments and length of time from initial diagnosis to relapse. The chemotherapy for advanced recurrent cancer may consist of a single drug or a combination of drugs. The duration of treatment or continuation of treatment is determined by symptoms, extent of disease and treatment side effects. When the disease is no longer responding to chemotherapy or other therapies, these treatments are stopped to reduce side-effects and cost of care. At that time care does not stop but other treatments (pain medication etc) are continued to improve patient symptoms.
CHEMOTHERAPY SIDE-EFFECTS
These may be acute, occurring whilst the patient is on treatment. These are usually reversible.
They may also occur late and are not usually reversible.
ACUTE SIDE EFFECTS
Gastrointestinal side effects such as nausea and vomiting, diarrhoea, hair loss (alopecia) and treatment related fatigue have all occurred with breast cancer chemotherapy. Chemotherapy may suppress the function of the ovaries in premenopausal women and result in menopausal symptoms. Skin pigmentation may also occur. Patients may also notice problems with memory and concentration.
Many of these symptoms can be controlled and will disappear within weeks of completion of treatment.
LATE SIDE-EFFECTS
The development of an acute leukaemia is a rare complication of a particular class of chemotherapy drugs. Cardiac disease may also occur. Usually this risk increases with increasing doses of these drugs which is not usually reached in treatment of patients.
Other systemic treatments for breast cancer include hormonal therapy and monoclonal antibody therapy.
Dr. Gilian Wharfe is an oncologist.
