This is a prospective randomized Phase III trial to assess efficiency of two post mastectomy hypofractionation schedules (40 Gy /15 fx / 3 weeks, 5 days per week VS 28.5 Gy delivered in 5 once-weekly fractions of 5.7 Gy each week) as adjuvant radiotherapy in female patients with breast cancer after mastectomy.

166 patients of breast cancer patients after mastectomy ( 83 patients in each arm ) will be randomize into 2 hypofractionation arms : Arm A: 40 Gy /15 fx / 3 weeks, 5 days per week . Arm B: 28.5 Gy delivered in 5 once-weekly fractions of 5.7 Gy each week.

Simulation:

Patient will be simulated on CT simulator using breast wedge with angle. Serials will be taken every 2 mm from upper neck down to mid abdomen.

Contouring:

CTVcw, CTVRNI will be contoured through RTOG guidelines . PTV is added as 0.5 cm all around CTV. Lungs, Heart, brachial plexus, spinal cord, esophageus and thyroid will be contoured as OAR. (www.rtog.org/CoreLab/ContouringAtlases/BreastCancerAtlas.aspx).

D)Dose Constraints:

Arm A:

PTV EVAL ( CW) : V90 % ≥ 90 %. - V105 % ≤ 5% - V107%≤ 3 %. Ipsilateral lung: V20 less than 20-25% - V 8 less than 35%- Contra lateral lung: V4 less 10 %. Heart: V16 less than 5% (Lt sided). V20 less than 5% (Lt sided). V16 is 0%.(Rt sided) V20 is 0% (Rt sided). Mean heart dose ≤ 320-400 cGy. Contra lateral breast : D max≤ 240 cGy. V 144 cGy less than 5 %. SCV : V90 % ≥ 90 %. Thyroid : Mean dose less than 35 Gy - V30 less than 50 %.

Arm B:

PTV EVAL ( CW) : V90 %≥ 90 %. - V105 %≤ 5% - V107%≤ 2 %.

Ipsilateral lung: V30%less than 15 -20% - V15% less than 30-35% - V5 % less than 50-55%.

Contra lateral lung : V5 % less than 5%. Heart :V25 % less than 5 % - V5 % less than 30 - 35 %. Contra lateral breast: V3 % less than 5 %. SCV : V90 % ≥ 90 %.

Follow up:

A)Weekly follow up will be done during sessions then regular clinical exam every 3 months to assess :

1. Acute and late toxicity regarding pain, pulmonary toxicity, dysphagia, skin toxicity and lymphedema.Assessment will be done according to RTOG and CTCv.5.
2. Any local (chest wall) recurrence, regional (nodal) recurrence.

B)Annual Mammogram. C)Any another investigation (once indicated)

Inclusion Criteria:

• Invasive carcinoma of the breast.
• Complete microscopic excision of primary tumour and axillary dissection or SLNB .
• Females with locally advanced breast cancer ( T3/T4 or N + or both ) who are candidate for neoadjvant chemotherapy regardless pathological stage after mastectomy.
• Patients with pathological stage (T3/ T4, +/- N+) or ( N+, any T) after upfront mastectomy.
• Able to comply with follow up.
• Written informed consent

Exclusion Criteria:

• Patients do not match with inclusion criteria.
• Collagen vascular disease, specifically systemic lupus, or scleroderma.
• Pregnancy or lactation at the time of radiotherapy.