Design: Phase 3, randomised, open-label, non-inferiority; 10-year analysis
Population: 810 women with high-risk breast cancer after mastectomy
Primary outcome: Locoregional recurrence (5-year primary; 10-year descriptive)
Effect: 10-year LRR 12.0% vs 10.3%; HR 1.19 (0.79–1.82)

CHN HYPOPMRT was a randomised, open-label, non-inferiority phase 3 trial at a national cancer centre in China. It enrolled 820 women with high-risk breast cancer after modified radical mastectomy and axillary dissection; 94% had stage III disease and median age was 49. Chest wall and supraclavicular radiotherapy was given as 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, ten-year locoregional recurrence 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: ischaemic heart disease 1% in each arm, lymphoedema about 1%, shoulder dysfunction under 1%. There was no brachial plexopathy and no grade 4–5 toxicity.

The trial met non-inferiority at five years; this ten-year analysis was descriptive. Together they support three-week postmastectomy regimens including the supraclavicular field — a major gain in Indian centres where linear accelerator time is scarce and patients travel far for daily treatment. The internal mammary nodes were not treated, so the result does not directly cover regimens that include them.

Consider 15-fraction postmastectomy radiotherapy to chest wall and supraclavicular nodes for high-risk breast cancer.
Late severe toxicity was rare and no higher than with 25 fractions at ten years.
The trial did not include internal mammary nodal irradiation.
Shorter courses free machine time and reduce travel burden for patients.

Why it matters

Ten-year data remove the main worry about hypofractionation with nodal irradiation: late toxicity.

The statistics, in plain English

A hazard ratio of 1.19 with an interval of 0.79–1.82 means the ten-year data cannot exclude a modestly higher recurrence rate with hypofractionation, but the absolute difference was 1.7 percentage points and the primary five-year non-inferiority test was met.