Table 1.

Summary of biomarker-directed ‘avoidance of radiotherapy’ studies

Study name (date opened)	Country of origin	Study design	Eligibility criteria (age)	Margin requirement after breast-conserving surgery	Eligibility criteria (T1, grade 1–2, ER/PR-positive HER2-negative, node-negative)	Eligibility criteria (additional)	Anticipated ipsilateral recurrence rate	Expected recruitment (patient number)
PRIMETIME (May 2017) [38]	UK	Prospective cohort	≥60 years∗	≥1 mm microscopic, circumferential margins of normal tissue from invasive cancer and DCIS	✓	Ki-67 to determine IHC4+C	≤4% at 5 years	1500
LUMINA (July 2013) [39]	Canada	Prospective cohort	>55 years	≥1 mm microscopically clear resection margins for invasive disease and DCIS or no residual disease on re-excision	✓	IHC including ER/PR/HER2, Ki-67 to determine luminal A subtype	<5% at 5 years <10% at 10 years	500
IDEA (March 2015) [40]	USA	Prospective cohort/single group assignment	50–69 years	Margins of excision ≥2 mm	Also included grade 3	Oncotype-DX RS ≤ 18	<6% at 5 years	200
PRECISION (May 2016) [41]	USA	Phase II prospective cohort	50–75 years	Negative margins (‘no ink on tumour’) or re-excision showing no residual disease in the re-excision specimen	✓	PAM-50 (luminal A subtype, low-risk ROR)	<5% at 5 years	690
EXPERT (August 2017) [42]	Australia and New Zealand	Randomised controlled trial	≥50 years	Microscopically negative margins for invasive carcinoma and any associated DCIS (no cancer cells adjacent to any inked edge/surface of specimen) or re-excision showing no residual disease	✓	PAM-50 (luminal A subtype, ROR ≤60)	≤4% at 5 years	1170

DCIS, ductal carcinoma in situ; ER, oestrogen receptor; PR, progesterone receptor; RS, recurrence score; IHC4+C, IHC4+Clinical; ROR, risk of recurrence.

^∗Younger patients are eligible if they are postmenopausal and have comorbidities that imply a high risk of radiotherapy toxicity.