Scientists from Cancer Research UK and the Medical Research Council have found that radiotherapy reduces the rate of recurrence in the same breast for this kind of cancer, known as Ductal Carcinoma in Situ (DCIS), by 60 per cent. But tamoxifen only cuts the chance of cancer returning by 10 per cent.
Professor Jack Cuzick, an epidemiologist who led the study for Cancer Research UK, says: “It is clear that radiotherapy is needed for the majority of women with DCIS. Tamoxifen should be limited to women who have oestrogen-sensitive cancers.
“Treatment is given after complete local excision, which is also known as lumpectomy. The main difference for women is that radiotherapy involves an intensive course of treatment for five weeks whereas tamoxifen is given as a pill for five years.”
These results form part of the first report in an ongoing trial of 1700 women from the UK, Australia and New Zealand who have been studied since 1990.
The benefits of radiotherapy were similar in women who were also taking tamoxifen as in those who were treated with radiotherapy alone.
The report challenges results from an earlier US trial which found tamoxifen was highly effective in reducing the risk of cancer coming back. But Cancer Research UK scientists believe this was because a much larger proportion of the patients in the American study were under 50.
In Europe most cases of DCIS are diagnosed in women older than 50 because that is the age at which they are invited for screening. In the UK, diagnosis of DCIS was rare before the screening programme began in 1988; when it was found, women were often given mastectomies which led to criticism of over treatment by some experts.
Since the screening programme an increasing number of cases have been picked up and, today, patients are most likely to have lumpectomies followed by treatment.
Dr Richard Sullivan, Head of Clinical Programmes at Cancer Research UK, says: “Despite substantial improvement in breast cancer survival many aspects of treatment need to be refined. The data from this study lends support to the use of radiotherapy after breast conserving surgery for localised DCIS.
“Ongoing research needs to be completed before we get a complete picture of how best to use radiotherapy and tamoxifen to treat women with this type of breast cancer.”
- The Lancet362 pp. 95-102
The number of women diagnosed with DCIS is growing because it is being picked up on mammograms when women are screened for breast cancer.
When DCIS is detected it means that cells inside some of the milk ducts of the breast have started to turn into cancer cells.
As these cells are all inside the ducts, there is very little chance that any of the cells have spread to the lymph nodes or elsewhere in the body.
In the past recommended treatment for DCIS was usually mastectomy. Now most cancer centres remove only the area of DCIS with a border of healthy tissue round it; this is called wide local excision or conservative surgery.
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