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Hypofractionated radiotherapy—radiation given in fewer, larger fractions resulting in a lower overall dose—was as effective as standard radiotherapy in reducing the risk of recurrence in early breast cancer, for patients in a pair of large multicenter trials.
This therapy also was associated with less morbidity, lead investigator Dr. John A. Dewar of the University of Dundee, Scotland, said at a press briefing. "We believe that hypofractionation is likely to be better than current radiation schedules because we are seeing less morbidity and equivalent local control with a median follow-up of 5 years in about 4,500 patients," he said.
The Standardization of Breast Radiotherapy (START) trials A and B tested the benefits of fraction sizes greater than the standard 2 Gy. The trials were conducted in parallel at 35 sites, accounting for nearly two-thirds of centers, in the United Kingdom.
Trial A randomized 2,236 patients to receive either the current standard of 50 Gy of radiation delivered in 25 fractions 5 days a week over 5 weeks (749 patients) or a hypofractionated schedule of 41.6 Gy (737 patients) or 39 Gy (750 patients) delivered in 13 fractions on alternate days over 5 weeks. Trial B randomized 2,215 patients to the current standard, as in trial A (1,105 patients), or to receive 40 Gy of radiation delivered in 15 fractions over 3 weeks (1,110 patients).
All study participants had completely excised invasive breast cancer. The median age was 57 years, with the majority having had breast-conserving surgery and radiotherapy confined to the breast and chest wall. Most had favorable prognostic profiles.
At a median follow-up of 5.1 years for trial A and 6 years for trial B, results showed that 39 Gy delivered in 13 fractions and 40 Gy delivered in 15 fractions had milder effects on healthy breast tissue than did the standard 50 Gy delivered in 25 fractions. However, 41.6 Gy delivered in 13 fractions had similar effects as the standard 50 Gy given in 25 fractions.
Cancer control in the breast was effective in all groups, with 3.4% (151 patients) experiencing local recurrence at 5 years. No loss was seen in patients randomized to fewer, larger fractions.
Achieving equally good disease control with less radiation is a win-win situation for patients, said Dr. Julie Gralow, professor of medicine at the University of Washington, Seattle, who moderated the press briefing. "I see patients every day in my clinical practice who have fibrosis, edema, and damaged breast tissue from their radiation. It would be terrific if we could get less long-term complications in less time with no sacrifice of control," she said.
Researchers are investigating other methods of breast radiation, including partial breast radiation focusing on the area around the tumor bed after lumpectomy, she added: "We need to see the long-term outcome from those studies before they become standard of care, but the exciting news is, we're looking at getting less morbidity with potentially better outcomes."
Dewar J.A. et al. Hypofractionation for early breast cancer: First results of the UK Standardisation of Breast Radiotherapy (START) trials. Abstract LBA518.
Commentary |
Radiation after breast-conserving surgery clearly reduces locoregional recurrence. It is usually given in small fractions daily over 5 to 6 weeks. This study evaluated three shorter hypofractionation schedules. All gave equivalent local control at a median of 5 years' follow-up with similar-to-improved local toxicity, compared with the standard schedule. Additional techniques are being investigated, including local radiation delivered via probes to the tumor bed. We should be able to offer women shorter-duration options for local radiation—potentially with reduced toxicity. — Hope S. Rugo, M.D.
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