Estimate of Amount of Radiotherapy Dose wasted in compensating for Tumour Growth between Treatments

For the first time, researchers have estimated the daily dose of radiotherapy that could be wasted in compensating for cancer cell growth that occurs overnight and during weekends in patients with early breast cancer.

The new study suggests that shorter radiotherapy schedule may:

• be more effective against breast cancer recurrence
• reduce the chances of side-effects on the surrounding normal tissues
• be more convenient for patients
• be much more cost-effective for health services

Read ECC 2013 Press Release: First Estimate of Amount of Radiotherapy Dose Wasted in Compensating for Tumour Growth between Treatments
by EUROPEAN SOCIETY FOR MEDICAL ONCOLOGY, 30 Sep 2013.

Abstract

Background and purpose

Randomised trials testing 15- or 16-fraction regimens of adjuvant radiotherapy in women with early breast cancer have reported favourable outcomes compared with standard fractionation. To evaluate hypofractionation further, two 5-fraction schedules delivering 1 fraction per week have been tested against a 25-fraction regimen.

Materials and methods

Women aged ⩾50 years with node negative early breast cancer were randomly assigned after microscopic complete tumour resection to 50 Gy in 25 fractions versus 28.5 or 30 Gy in 5 once-weekly fractions of 5.7 or 6.0 Gy, respectively, to the whole breast. The primary endpoint was 2-year change in photographic breast appearance.

Results

Nine hundred and fifteen women were recruited from 2004 to 2007. Seven hundred and twenty-nine patients had 2-year photographic assessments. Risk ratios for mild/marked change were 1.70 (95% CI 1.26–2.29, p < 0.001) for 30 Gy and 1.15 (0.82–1.60, p = 0.489) for 28.5 Gy versus 50 Gy. Three-year rates of physician-assessed moderate/marked adverse effects in the breast were 17.3% (13.3–22.3%, p < 0.001) for 30 Gy and 11.1% (7.9–15.6%, p = 0.18) for 28.5 Gy compared with 9.5% (6.5–13.7%) after 50 Gy. With a median follow-up in survivors of 37.3 months, 2 local tumour relapses and 23 deaths have occurred.

Conclusions

At 3 years median follow-up, 28.5 Gy in 5 fractions is comparable to 50 Gy in 25 fractions, and significantly milder than 30 Gy in 5 fractions, in terms of adverse effects in the breast.