Hypofractionated post-mastectomy radiotherapy: durable at ten years

Design

Phase 3, randomised, open-label non-inferiority trial, 10-year analysis

Population

810 women with high-risk breast cancer after mastectomy, 94% stage III

Primary outcome

Locoregional recurrence

Effect

10-year: 12.0% vs 10.3%; HR 1.19 (95% CI 0.79–1.82)

CHN HYPOPMRT, a single-centre, open-label phase 3 trial in China, randomised 820 women with high-risk breast cancer after modified radical mastectomy, 94% with stage III disease and median age 49, to chest wall and supraclavicular radiotherapy of 50 Gy in 25 fractions over five weeks or 43.5 Gy in 15 fractions over three weeks.

At a median follow-up of 11.5 years, locoregional recurrence at 10 years was 10.3% with conventional and 12.0% with hypofractionated treatment (HR 1.19, 95% CI 0.79–1.82). Grade 3 late effects were uncommon and similar, including ischaemic heart disease in 1% of each group and lymphoedema in about 1%. There were no grade 4 or 5 events and no brachial plexopathy.

The five-year results established non-inferiority; this analysis shows the result held. For many Indian patients, who often travel long distances and stay away from home for radiotherapy, two fewer weeks is a real gain in cost and completion. Breast reconstruction is not reported, so the findings should not be assumed to cover that setting.

• Offer 15-fraction post-mastectomy radiotherapy to the chest wall and supraclavicular region in high-risk breast cancer.
• Use the shorter course to reduce travel, cost and treatment interruptions.
• Expect similar late toxicity, including cardiac and lymphoedema rates, to conventional schedules.
• Apply with caution after breast reconstruction, which this trial did not report on.
• Follow patients for locoregional recurrence as with conventional treatment.

Why it matters

Long-term data now support a shorter schedule in exactly the setting where evidence had been thin.

Don't overread it

The ten-year comparison was not a confirmatory non-inferiority test.

The statistics, in plain English

A hazard ratio of 1.19 with an interval from 0.79 to 1.82 means no difference was detected, though the interval leaves room for a modest increase in recurrence. The 10-year analysis was descriptive; the formal non-inferiority test was at five years.

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