This randomized phase III trial studies how well hypofractionated radiation therapy works in preventing recurrence in patients with stage IIa-IIIa cancer who have undergone mastectomy. Hypofractionated radiation therapy delivers higher doses of radiation therapy over a shorter period of time and may kill more tumor cells that remain after surgery and have fewer side effects.

PRIMARY OBJECTIVES:

I. To evaluate whether the reconstruction complication rate at 24 months post radiation is non-inferior with hypofractionation.

SECONDARY OBJECTIVES:

I. To evaluate the incidence of acute and late radiation complications, based on Common Terminology Criteria for Adverse Events (CTCAE) 4.0 toxicity.

II. To evaluate the local and local regional recurrence rate. III. To compare reconstruction complication rates based on reconstruction method (autologous +/- implant versus [vs] implant only) and timing of reconstruction received (immediate vs. intent for delayed).

TERTIARY OBJECTIVES:

I. To evaluate reconstructed breast photographic cosmetic scores with hypofractionated radiation compared to standard fractionation 24 months after radiation.

II. To evaluate reconstructed breast photographic cosmetic scores 24 months after radiation based on the method and timing of reconstruction received.

III. To estimate the incidence of arm lymphedema by treatment arm. IV. To compare physical well-being, psychosocial well-being, sexual well-being, satisfaction with breast/nipples/abdomen, and satisfaction with overall outcome between the treatment arms at 24 months after radiation.

V. To estimate patient satisfaction with trial participation by treatment arm as measured by the Was It Worth It Questionnaire at 24 months after radiation.

VI. To compare the direct and indirect patient costs for radiation therapy by treatment arm.

VII. To compare patient reported total health care service utilization 12 months after the completion of radiation.

VIII. To compare the economic impact of treatment. IX. To analyze polymorphisms in MDM2 and in genes including TP53, ATM, TGFB1, IL4, IL6, and IL10 and determine correlations with a higher likelihood of adverse radiation reactions (radiation sensitivity) and with toxicities.

X. To analyze polymorphisms in MDM2 and in genes including TP53, ATM, TGFB1, IL4, IL6, and IL10 to determine correlations with secondary endpoints such as local-regional control.

OUTLINE: Patients are randomized to 1 of 2 groups.

GROUP I: Patients undergo radiation therapy daily on Monday-Friday for 5-6 weeks.

GROUP II: Patients undergo hypofractionated radiation therapy daily on Monday-Friday for 3-4 weeks.

After completion of study, patients are followed up for 5 years.

Inclusion Criteria:

• Histologically confirmed invasive carcinoma of the breast of any of the following histologies (ductal, lobular, mammary, medullary, or tubular); patients with metaplastic breast cancer are not eligible

• Patients will be staged according to the TNM staging system

  • For patients not receiving neoadjuvant chemotherapy, pathologic staging must be T0N1-2a, T1N1-2a, T2N1-2a, T3N0-2a, and all M0 status
  • For patients receiving neoadjuvant chemotherapy, clinical pre-chemo staging and post mastectomy pathological staging is required for all patients; patients who have received neoadjuvant chemotherapy and are pathologically cT0-2 and N0 are only eligible if biopsy-proven clinically N1 or N2 disease is documented prior to the start of neoadjuvant chemotherapy; cT3N0 patients or ypT3N0 patients who receive neoadjuvant chemotherapy may be eligible based on clinical or pathological T stage, and do not require pathologically positive lymph nodes
  • Note: Higher of the clinical or pathological T and N stage are used for final staging, if receiving neoadjuvant chemotherapy; all patients with clinical, radiographic or pathological T4, N3 or involved internal mammary disease (N1b, N1c, and N2b) are not eligible. N1mic patients are eligible.

• No prior therapeutic radiation therapy to the chest, neck or axilla; prior radioactive oral iodine is permitted

• No prior history of ipsilateral breast cancer (invasive disease or ductal breast carcinoma in situ [DCIS]); lobular carcinoma in situ (LCIS) and benign breast disease is allowed

• No history of prior or concurrent contralateral invasive breast cancer; benign breast disease, LCIS or DCIS of contralateral breast is allowed

• No active collagen vascular diseases, such as: systemic lupus erythematous, scleroderma, or dermatomyositis

• Negative inked histologic margins from mastectomy pathology (no invasive cells at margin). Patients with DCIS at margin are eligible.

• No significant post mastectomy complications in the ipsilateral breast requiring an unplanned re-operation or admission for intravenous (IV) antibiotics; re-operation for margins evaluation, nodal completion and routine reconstruction is acceptable

• Radiation oncologist intends to treat all target volumes and respect all normal tissues in accordance with the dosimetric constraints described (simulation before registration recommended)

• Radiation oncologist is planning to treat regional lymph nodes including internal mammary nodes and meet acceptable protocol dosimetric requirements

• Radiation oncologist is NOT planning to utilize a chest wall/scar boost

• Patient must have undergone immediate reconstruction at the time of mastectomy or be planning to undergo reconstruction within 18 months after radiation

• Treating physician and patient must plan to start radiation treatment within the timeframes specified in protocol.

• If a tissue expander is utilized it needs to be a fluid filled expander, NO air expander (unless completely deflated) during radiation therapy

• For patients with diabetes, hemoglobin A1C test must have been performed =< 90 days prior to registration

• No co-existing medical conditions with life expectancy < 5 years

• No other malignancy within 5 years of registration with the exception of basal cell or squamous cell carcinoma of the skin treated with local resection only or carcinoma in situ of the cervix

• Negative pregnancy test (serum or urine HCG) in women of child-bearing potential ≤ 7 days prior to registration. Patients who have received a bilateral tubal ligation still require a negative pregnancy test for eligibility. A female of childbearing potential is a sexually mature female who has not undergone a hysterectomy or bilateral oophorectomy and has not been naturally postmenopausal for at least 12 consecutive months

• Women of child-bearing potential must agree to utilize a form of birth control or agree to undergo sexual abstinence during radiation therapy

• Eastern Cooperative Oncology Group (ECOG) (Zubrod) performance status 0-1

• Patients must be able to read and comprehend English, in order to be able to complete study questionnaires; however, patients participating through Canadian Cancer Trials Group (CCTG) institutions who can read and comprehend French are eligible