Inclusion criteria:

Women aged ≥ 40 years; histologically confirmed invasive breast cancer or ductal carcinoma in situ (DCIS) UICC stage 0–IIA, a maximum tumour diameter < 3 cm, complete resection with clear margins ≥2 mm (in case of invasive lobular cancer or pure DCISP5 mm), at least six negative axillary lymph nodes (pN0), or singular nodal micro-metastasis (pN1mi), or negative sentinel node biopsy (pN0sn), or a clinically negative axilla in case of DCIS (cN0), no distant metastasis or contralateral breast cancer.

Exclusion criteria:

Any signs of a multifocal growth pattern in mammography, had residual micro-calcifications post-operatively, an extensive intraductal component (EIC), vessel invasion (L1, V1), involved, close (<2 mm) or unknown margins (R1/Rx), or were pregnant.

1) APBI Interstitial brachytherapy; HDR 32 Gy/8 fractions or 30.3 Gy/7 fractions; PDR 50 Gy at 0.6–0.8 Gy/fractions given hourly.

2) External beam WBRT 50.0–50.4 Gy/1.8–2.0 Gy fractions (5–28) plus 10 Gy/5 fraction boost.

Inclusion criteria:

Women ≥ 50 years undergoing breast conserving surgery for unifocal invasive ductal adenocarcinoma of any grade (1–3); pathological tumour size ≤ 3 cm (pT1–2), axillary node negative or one to three positive nodes (pN0–1), microscopic margins of non-cancerous tissue ≥ 2 mm.

Exclusion criteria:

Women < 50 years; Invasive carcinoma of classical lobular type; distant metastases; previous malignancy of any kind (unless non-melanomatous skin cancer); undergone a mastectomy; received neoadjuvant chemotherapy or concurrent adjuvant chemoradiotherapy.

• 1) Whole-breast radiotherapy received 40 Gy in 15 fractions to the whole breast.
• 2) Reduced-dose group received 36 Gy in 15 fractions to the whole breast and 40 Gy in 15 fractions to the partial breast containing the tumour bed.
• 3) Partial-breast group received 40 Gy in 15 fractions to the partial breast only.

Inclusion criteria:

Age at presentation >40 years; Tumour size ≤25 mm; Wide excision or quadrantectomy with clear margins (≤5 mm); Clips placed in tumour bed; Full informed consent from patient; Follow-up at the radiotherapy department of Florence University.

Exclusion criteria:

Women ≤ 40 years; Cardiac dysfunction (Left ventricular ejection fraction <50% as measured by echocardiography or history of active angina, myocardial infarction, or other cardiovascular disease); Forced expiratory volume <1 L/m; Extensive intraductal carcinoma; Multifocal cancer; Psychiatric problems; Follow-up at centre other than the radiotherapy department of Florence University.

1) Partial breast irradiation or accelerated partial breast irradiation using intensity-modulated radiotherapy (IMRT).

2) Whole breast radiotherapy (WBRT); used 50 Gy/25 fractions plus 10 Gy boost.

Inclusion criteria:

Women > 40 years; Wide excision with microscopically negative surgical margins; unifocal tumour; primary tumour size ≤20 mm (pT1); cN0, pN0, or pN1mi (single nodal micrometastasis >0.2mmand≤2.0 mm) axillary status; and histologic Grade 2 or less.

Exclusion criteria:

Women ≤ 40 years; bilateral breast carcinoma; prior uni- or contralateral breast cancer; concomitant or previous other malignancies (except basal cell carcinoma of the skin); pure ductal or lobular carcinoma in situ (pTis); invasive lobular carcinoma; or the presence of an extensive intraductal component.

1) PBI; 7 × 5.2GyHDRmulti-catheter brachytherapy (88/128 women). Those unsuitable for HDR (40/1280 women) had 50 Gy/25 fractions electron beam RT to partial breast.

2) Control arm: 50 Gy/25 fractions WBRT (130 women)

Inclusion criteria:

Women ≥ 40 years with invasive ductal carcinoma or ductal carcinoma in situ (DCIS) treated with BCS with microscopically clear margins and negative axillary nodes by sentinel node biopsy, or axillary dissection for those with invasive disease, or by clinical examination for those with DCIS alone.

Exclusion criteria:

Women < 40 years; combined tumour size (DCIS and/or invasive carcinoma)>3 cm, lobular carcinoma, > one primary tumour in different quadrants of the breast, or an RT plan that did not meet protocol-defined dose-volume constraints for APBI.

1) APBI using three-dimensional conformal radiotherapy (3D-CRT): 38.5 Gy in 10 fractions, bd over 5–8 days. 6–8 hour gap between doses.

2) WBRT; 42.5 Gy in 16 fractions daily over 22 days. Women with large breast size: 50 Gy in 25 fractions over 25 days. Boost 10 Gy in 4 or 5 fractions over 4–7 days was permitted women who were deemed at moderate to high risk of LR according to local cancer centre guidelines.

Inclusion criteria:

Women age ≥60 years; invasive ductal carcinoma; unifocal tumour; primary tumour size ≤30 mm (pT2); cN0, pN0 axillary status; and histologic grade 2 or less.

Exclusion criteria:

Women age <60 years; Bilateral breast carcinoma; prior unilateral or contralateral breast cancer; concomitant or other previous malignancies; pure ductal or lobular carcinoma in situ (pTis); invasive lobular carcinoma; presence of an extensive intraductal component; excision with microscopically positive or close (3 mm) surgical margins; multicentric disease; nodepositive disease; concomitant or neoadjuvant chemotherapy; and postsurgical hematoma >2 cm, or seroma fluid that required multiple aspirations.

1) PBI/APBI delivered by 3D-CRT at 48Gy/24 fractions ± 10 Gy boost (according to risk factors for local recurrence) in 51 women.

2) Conventional WBRT at 48 Gy/24 fractions ± 10 Gy boost in 51 women.