Less Radiation Equally Effective in Early Breast Cancer
Hypofractionated radiotherapy—a shorter course of higher doses resulting in less overall radiation—appears to be as effective in early breast cancer as the historical standard regimen, according to long-term results from two studies published in The Lancet Oncology.
Early breast cancer is often treated with the surgical removal of the cancer followed by radiation therapy to kill any remaining cancer cells. Historically, standard radiation treatment is a five-week process and consists of 50 Gray of radiation delivered in 25 two-Gray doses. This is a significant time commitment for patients, not to mention the concerns about high doses of radiation.
An alternative to the traditional regimen is hypofractionated radiation therapy, which involves fewer radiation treatments with a higher dose of radiation at each treatment—but a lower cumulative dose over the course of treatment.
After 10 years of follow-up from two trials in the UK—START-A and START-B—researchers have found that there is no significant difference in rates of local-regional relapse with the use of hypofractionated radiation therapy compared with standard radiation therapy. What’s more, both trials demonstrated evidence that the effects of radiation on normal tissue were lower with hypofractionated regimens.
Overall, the two trials included 4,451 women from 35 radiotherapy centers who were randomly assigned to the standard regimen or a hypofractionated regimen, which consisted of 41.6 Gray or 39 Gray given in 13 fractions over 5 weeks in START-A or 40 Gray in 15 fractions over 3 weeks in START-B.
After a median follow-up of 9.3 years in START-A, researchers observed 139 local-regional relapses. The rates of relapse among the arms were: 7.4 percent for the standard 50-Gray regimen, 6.3 percent for the 41.6-Gray regimen and 8.8 percent for the 39-Gray regimen.
After a median follow-up of 9.9 years in START-B, there were 95 local-regional relapses—4.3 percent in the 40-Gray group and 5.5 percent in the 50-Gray group.
There were also differences in the effects on normal tissue. In START-A, there was little difference between the 41.6 Gray and the 50-Gray regimens, but conditions such as breast edema, telangiectasia (spider veins), and breast induration (hardening) were significantly less common in the 39-Gray compared with the 50-Gray regimen. In the START-B trial, breast shrinkage, telangiectasia, and breast edema were significantly lower with 40 Gray than with 50.
The researchers concluded that hypofractionated radiotherapy is safe and effective for patients with early breast cancer. They speculate that the results support the continued use of 40 Gray in 15 fractions, a regimen that has already been widely adopted in the UK as standard treatment for women with early breast cancer.
Haviland JS, Owen JR, Dewar JA, et al. The UK Standardisation of Breast Radiotherapy (START) trials of radiotherapy hypofractionation for treatment of early breast cancer: 10-year follow-up results of two randomised controlled trials. The Lancet Oncology. 2013; 14(11): 1086 – 1094.
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