Women with breast cancer are less likely to relapse if they undergo radiotherapy after surgery, according to a new study.
Early, low-risk, hormone driven breast cancer is less likely to come back if patients are given radiotherapy and anti-hormone treatment post-operation, suggest the findings.
Scientists followed almost 900 post-menopausal women for ten years. The groups were randomly given either whole breast irradiation (WBI) or just anti-hormone treatment after breast surgery.
WBI is a common type of radiation treatment where a large machine shoots radiation at the affected breast.
They found that cancer did not return in the same breast in 97.5 percent of women who had WBI.
Cancer came back in five per cent more women who did not have WBI than those who did.
In a follow up ten years later, of the 439 women who had WBI there were ten recurrences of cancer in the same breast.
Of the 430 women who only had anti-hormone treatment, 31 women had cancer recurrences.
When researchers looked at how long the women survived without their disease recurring, 94.5 per cent of women who had WBI survived disease-free, compared to 88.4 per cent of women who didn’t
While these results are promising, the cost and negative side effects associated with WBI means researchers are trying to identify a subgroup of breast cancer patients who might not need radiotherapy at all.
Unfortunately, the results from this study mean that might not be possible.
The patients in the trial had early, low-risk tumours that were either grade one or two, less than three cm in diameter and without any cancer cells identified in the lymph nodes.
The tumours were driven by hormones such as oestrogen or progesterone and so would respond to anti-hormone therapies such as tamoxifen or anastrozole.
The patients had received no previous chemotherapy, radiotherapy or hormone therapy.
WBI was given daily for 39 days and within six weeks of surgery.
If the cancer had spread to the first sentinel lymph nodes under the arm, it would be removed along with the axillary lymph node that is also in the armpit.
If no cancer was found in the sentinel lymph node, no axillary nodes were removed.
Researchers found that in the 258 women who had only the sentinel nodes removed, there was a 75 per cent lower risk of cancer coming back if they had WBI than if they did not.
However, the same advantage in disease-free survival was not seen for WBI after the axillary nodes were removed.
Overall rates of survival and surviving without cancer spreading to other parts of the body were similar between women who did or did not have WBI.
Associate Professor Gerd Fastner, from the Paracelsus Medical University in Salzburg, Austria, said: “Our findings show that radiotherapy is still highly effective in significantly improving local control and disease-free survival in combination with anti-hormones, compared to anti-hormones alone.
“This remains true after long-term follow-up of breast cancer patients with a good prognosis.
“In our analysis the omission of whole breast irradiation turned out to be the main predictor for in-breast recurrences.
“In addition, tumours that could not have their grade classified, had a nearly four-fold risk of recurring, which might be due to some of the tumours being more aggressive.
“Improving control of the tumour at the primary site may translate into better survival in future years.
“We believe that the additional benefits of postoperative radiotherapy have been confirmed in hormone receptor positive patients, regardless of whether or not they are at high risk of breast cancer recurrence.
“In the light of current knowledge, this does not necessarily mean that they have to have whole breast irradiation nowadays, since partial breast irradiation has proved to be competitive.
“Partial breast irradiation can be carried out with postoperative hypofractionated external beam radiotherapy, intraoperative techniques or perioperative brachytherapy.
“The total omission of radiotherapy should only be considered in frail, elderly patients who would not be able to tolerate such treatment.”
Head of the Department of Oncology at the University of Turin, Italy, Professor Umberto Ricardi said: “In 2006 these researchers reported results from nearly five years of follow-up for these women, which showed that radiotherapy after surgery, combined with treatment with tamoxifen or anastrazole, resulted in a significant reduction in the risk of the cancer returning.
“These new results, with ten years of follow-up, show that the beneficial effects of irradiation persist, becoming even more evident, for these women.
“This is important information for women and their doctors, which helps them to choose the best treatment for their breast cancer.
“Radiation treatments have progressed significantly since 2006 and now there are also other ways of delivering radiotherapy to the breast that are less toxic and time-consuming compared to whole breast irradiation.
“This study also emphasises the benefits of long-term follow-up for women and the medical community.”
Research was conducted by the Austrian Breast and Colorectal Cancer Study Group (ABCSG). It will be presented at ESTRO 38, Europe’s largest congress on radiation oncology.