The researchers followed up with a long-term, large clinical trial on radiation therapy for early breast cancer patients. The study hoped to see how the typical treatment of 25 small doses of radiation compared to about half as many larger doses with a smaller total dosage.
They found that the treatment courses were similarly safe and effective in killing cancer cells and preventing new tumors from forming. Also, some women who received less total radiation experienced less tissue damage.
This research could be used to change the standard treatment for patients with breast cancer.
John Yarnold, BSc, of The Institute of Cancer Research, London, and The Royal Marsden NHS Foundation Trust, Sutton, UK, and colleagues conducted this study in order to find out more about women's options for treating breast cancer.
Radiation therapy, or radiotherapy, is frequently used to treat cancer, including breast cancer. Radiation therapy involves using radiation to target and kill harmful cancer cells. It is commonly used in addition to chemotherapy.
Sometimes, radiation therapy comes with side effects like damage to the tissues surrounding the affected area.
Typically, patients with breast cancer receive about 25 small doses of radiation after surgery for treatment of early breast cancer.
In the United Kingdom, a series of long-term clinical trials called the Standardization of Breast Radiotherapy, or START, are meant to find the best course of treatment for breast cancer patients seeking radiation therapy. The researchers recruited women to participate in one of two subtrials, START-A or START-B, to test different dosages of radiotherapy.
START-A included 2,236 women and START-B included 2,215 women.
Women in the control group received the typical dose — two units of radiation 25 times. Others had smaller total doses but received more radiation each time — one group received three units of radiation 13 times, for example. All of the groups received their treatment over five weeks.
The START trials began 10 years ago. Five years ago, researchers followed up on the participants and found that lower total doses of radiation delivered in larger dose sizes fewer times may be as effective against cancer as the standard treatment of 25 small doses.
Doctors took data on how normal tissue responded to the radiation therapy and whether the patients experienced any tumor relapse.
Yarnold's study followed up on the START trials to see how the participants were doing 10 years after they began the trials.
The researchers' findings confirmed what they had seen five years after the beginning of the trial. Larger and fewer doses of radiation were just as effective against fighting breast cancer as smaller, more frequent doses.
The START-A trial showed that 41.6 units of radiation over 13 sessions was just as effective as the typical treatment of 50 units over 25 sessions. START-B confirmed that 40 units over 15 sessions was similarly effective.
However, the patients who received 40 units over 15 different sessions had less damage to their normal tissues that were not affected by cancer. They experienced less breast shrinkage, spider veins and breast swelling after treatment.
The researchers concluded that these findings, 10 years after the trials, suggest that larger, fewer doses of radiation and a smaller total dose were just as likely to control tumors as the standard dosage. They also emphasized the importance of ongoing and future trials similarly testing different dosages of radiation therapy.
"These high quality studies should give oncologists and breast cancer patients even more confidence that, when clinically appropriate, using a more convenient radiation therapy treatment regimen (3+ weeks in duration) is at least as effective and safe as the longer treatment regimens (approximately 5+ weeks) that have been used for many years in the management of breast cancer," Brian Lawenda, MD, Clinical Director of Radiation Oncology at 21st Century Oncology in Las Vegas, Nevada, told dailyRx News.
"Although the cosmetic results of this study need to be confirmed in other randomized trials, the data looks quite promising in that the shorter course treatment appears to be associated with fewer side effects on the affected breast such as, swelling, firmness, breast shrinkage, etc," said Dr. Lawenda. "Another advantage that shorter course treatments provide is a significantly lower financial burden to our patients and the healthcare system."
The study was published in The Lancet Oncology on September 18.
The research was funded by NHS funding to the NIHR Biomedical Research Centre and a core grant from Cancer Research UK.