EXPERT: This phase III trial is examining personalised radiation therapy for low-risk early breast cancerA Randomised Phase III Trial of Adjuvant Radiation Therapy Versus Observation Following Breast Conserving Surgery and Endocrine Therapy in Patients With Molecularly Characterised Luminal A Early Breast Cancer

Exclusion

Any one of the following is regarded as a criterion for exclusion from the study:

1. Primary tumour characteristics:

   • Presence of multifocal or multicentric invasive carcinoma or ductal carcinoma in situ;
   • Evidence of clinical or pathologic T4 disease (extension to the chest wall, oedema or ulceration of skin, satellite skin nodules, inflammatory carcinoma);
   • The invasive component of the primary tumour is present as micro-invasion only;
   • Grade 3 histology;
   • Presence of lymphovascular invasion
2. Contra-indication or unwillingness to have adjuvant endocrine therapy.
3. Planned to receive adjuvant chemotherapy or biologic therapy after breast cancer surgery, i.e. any systemic therapy other than endocrine therapy is not permitted. Any therapy unrelated to cancer is permitted at the discretion of investigators.
4. Treated with neoadjuvant endocrine therapy, chemotherapy or biologic therapy prior to breast cancer surgery.
5. Prior breast or thoracic RT for any condition.
6. Pre-operative breast imaging evidence of disease aside from the primary carcinoma resected by breast conserving surgery.
7. Concurrent invasive breast carcinoma or ductal carcinoma in situ (synchronous or metachronous).
8. Prior diagnosis of invasive breast carcinoma or ductal carcinoma in situ in either breast irrespective of disease free interval.

9. A diagnosis of non-breast malignancy <5 years prior to randomisation with the following exceptions:

   • Patients who are diagnosed with carcinoma in situ of cervix, endometrium or colon; melanoma in situ; and basal or squamous cell carcinoma of the skin at any time prior to randomisation are not excluded from study participation.
   • Patients who are diagnosed with other non-breast malignancy ≥5 years prior to randomisation and without evidence of disease recurrence are not excluded from study participation.
10. Significant comorbidity precluding definitive RT for breast cancer (e.g. cardiovascular or pulmonary disease, scleroderma, systemic lupus erythematosus).
11. Life expectancy <10 years.
12. Documented mutation of BRCA1, BRCA2 or TP53, or at high genetic risk of breast cancer.
13. Pregnant or lactating patients.
14. Inability to be registered to the study ≤8 weeks after the last surgical procedure for breast cancer.
15. Inability to commence RT (if randomised to receive RT) no later than 12 weeks from the last surgical procedure for breast cancer.
16. Inability to provide written informed consent.
17. Psychiatric, addictive, or any disorder that precludes compliance with protocol requirements.