Axillary node positive

No neoadjuvant systemic therapy

No previous history of cancer

Intervention arm (IM RT+): Radiation once per day at a dose of 1.8–2 Gy, up to a total dose of 45–50.4 Gy. No strict guidelines on radiotherapy technique. Most common technique was partial wide tangent.

Control arm (IM RT-): Radiation once per day at a dose of 1.8–2 Gy, up to a total dose of 45–50.4 Gy. No strict guidelines on radiotherapy technique. Most common technique was standard tangent method.

Aged <75 years

Stage I or II adenocarcinoma of the breast (tumour >1cm)

Undergoing modified radical mastectomy

Positive axillary nodes or medial/central tumour ± positive axillary nodes

70% Karnofsky performance scale

No bilateral breast cancer, history of cancer, or severe comorbidity.

Intervention arm (IM RT+): 50 Gy or equivalent. Ipsilateral parasternal area, including the internal mammary chain, was treated using a combination of photons and electrons up to a total of 12.5 Gy, given in 5 fractions (2.5 Gy per fraction, 4 fractions per week) and 9–12 MeV electrons up to a total of 32.5 Gy, given in 13 fractions (2.5 Gy per fraction, 4 fractions per week) for a total treatment time of approximately 5 weeks. The lateral and superior edges of the IMN field were matched to the field irradiating the chest wall and the supraclavicular field.

Control arm (IM RT-): 50 Gy or equivalent. The internal border of the chest wall field was placed at the external border of a sham internal mammary node field and care was taken to avoid inclusion of the first intercostal spaces in the supraclavicular field.

N0-N2

Centrally or medially located tumours could be N− or N+. Externally located tumours had to be N+

Intervention arm (IM RT+): Prescribed radiotherapy dose was 50 Gy in 25 fractions of 2 Gy - 26 Gy delivered with photons and 24 Gy delivered with electrons. One anterior field for the IM-MS radiation was recommended.

Control arm (IM RT-): no details reported.

Centrally or medially located tumours could be N− or N+. Externally located tumours had to be N+

Intervention arm (IM RT+): Regional nodal irradiation at a dose of 50 Gy in 25 fractions. No further information reported.

Control arm (IM RT-): No details reported.

Node positive

<70 at age of operation

Excluded patients who experienced recurrence before radiotherapy, were unfit for standard radiotherapy, only had micrometastatic nodes, or had prior malignancy

Intervention arm (IM RT+ [right sided cancers]): Radiotherapeutic dose to the breast/chest wall, scar, supraclavicular nodes, infraclavicular nodes, and axillary levels II to III was 48Gy in 24 fractions, administered in five fractions per week. The internal mammary nodes in intercostal spaces one to four were treated with anterior electron field or by inclusion in tangential photon fields.

Control arm: (IM RT- [left sided cancers]): Radiotherapeutic dose to the breast/chest wall, scar, supraclavicular nodes, infraclavicular nodes, and axillary levels II to III was 48Gy in 24 fractions, administered in five fractions per week.

Treated with breast conserving surgery and sentinel lymph node biopsy or axillary node dissection

Node positive or negative with high-risk features

Excluded if T stage 4, N2–3, serious non-malignant disease that would preclude radiotherapy, or had concurrent/previous malignancies, psychiatric or addictive disorders which precluded obtaining informed consent or adherence to protocol

Excluded if pregnant or lactating

Intervention arm (IM RT+): The breast was treated with dose of 50Gy in 25 fractions. Radiation of the internal mammary nodes (50Gy in 25 fractions) was performed using a modified wide-tangent technique or separate internal mammary node field plus tangents.

Control arm (IM RT-): The breast was treated with dose of 50Gy in 25 fractions.