Radiation-Free breast cancer treatment? new trial tests skipping it after chemo success

NCT ID NCT05866458

Recruiting now Disease control Sponsor: Ontario Clinical Oncology Group (OCOG) Source: ClinicalTrials.gov ↗

First seen Jun 27, 2026 · Last updated Jun 27, 2026

Summary

This study is testing whether women with early-stage breast cancer that has not spread to lymph nodes can safely skip radiation therapy after a lumpectomy, if their tumor completely disappeared with chemotherapy. The trial will enroll 352 women and follow them for cancer recurrence in the same breast. The goal is to reduce unnecessary treatment side effects without increasing the risk of cancer coming back.

What this could mean

Our plain-language read of the trial. This is informational only — not medical advice or a prediction.

Active substance: radiation therapy omission
What this could lead to: If successful, this could allow many women with early breast cancer to avoid radiation and its side effects after a good response to chemotherapy.
What could go wrong: This is a phase 3 trial, but it only includes a specific group (node-negative, complete response). The risk of cancer returning in the breast without radiation is unknown and may be higher than expected.

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Conditions

The condition(s) this trial relates to.

breast cancer breast neoplasm

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

BREAST CANCER

Contacts and locations

Locations

BC Cancer - Centre for the North
RECRUITING

Prince George, British Columbia, V2M 7E9, Canada
CHU de Quebec - Universite Laval
RECRUITING

Québec, Quebec, G1R 2J6, Canada
CHUM - Centre Hospitalier de L'Université de Montréal
RECRUITING

Montreal, Quebec, H2L 4M1, Canada
Cancer Centre of Southeastern Ontario at Kingston
RECRUITING

Kingston, Ontario, K7L 5P9, Canada
Centre Hospitalier Trois Rivieres Ste-Marie
RECRUITING

Trois-Rivières, Quebec, G8Z 3R9, Canada
Centre hospitalier de Lanaudière
RECRUITING

Saint-Charles-Borromée, Quebec, J6E 6J2, Canada
Jewish General Hospital
RECRUITING

Montreal, Quebec, H3T 1E2, Canada
Juravinski Cancer Centre
RECRUITING

Hamilton, Ontario, L8V 5C2, Canada
Latrobe Regional Health
RECRUITING

Traralgon, 3844, Australia
Liverpool Hospital
RECRUITING

Liverpool, New South Wales, 1871, Australia
Maroondah Hospital
RECRUITING

Box Hill, 3128, Australia
Mater Hospital Sydney
RECRUITING

North Sydney, New South Wales, 2060, Australia
McGill University Health Centre (MUHC)
RECRUITING

Montreal, Q, H4A 3J1, Canada
Monash Medical Centre -Moorabbin
NOT_YET_RECRUITING

Bentleigh East, Victoria, 3165, Australia
Prince of Wales Hospital
RECRUITING

Randwick, 2031, Australia
Royal Perth Hospital
NOT_YET_RECRUITING

Perth, 6000, Australia
Royal Victoria Regional Health Centre
RECRUITING

Barrie, Ontario, L4M 6M2, Canada
St. Vincent's Hospital Melbourne
RECRUITING

Melbourne, Victoria, 3065, Australia
Sunnybrook Health Sciences -Odette Cancer Centre
RECRUITING

Toronto, Ontario, M4N 3M5, Canada
Thunder Bay Regional Health Sciences Centre
RECRUITING

Thunder Bay, Ontario, P7B 6V4, Canada
Tweed Valley Hospital
RECRUITING

Cudgen, Cudgen, 2487, Australia
Victorian Breast & Oncology Care (VBOC)
RECRUITING

East Melbourne, Victoria, 3002, Australia
Westmead Hospital
RECRUITING

Westmead, New South Wales, 2145, Australia

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