Proton Radiation Therapy for Invasive Breast Cancer Following Mastectomy

To determine the feasibility of using proton radiation for the treatment of invasive breast cancer following mastectomy based on the occurrence of grade 3 or > radiation pneumonitis or any grade 4 adverse event within 3 months after the completion of radiation treatment.

Summary of the number of participants with any grade acute skin toxicities. Acute skin toxicity was assessed from the start of treatment until 90 days after the end of treatment. Skin toxicity was assessed using Common Terminology Criteria for Adverse Events (CTCAE 4).

The number of participants that experienced radiation pneumonitis within three months of the end of treatment. The participants that experienced radiation pneumonitis are grouped by grade. Adverse events were assessed using Common Terminology Criteria for Adverse Events (CTCAE 4).

• Grade 1: Mild
• Grade 2: Moderate
• Grade 3: Severe
• Grade 4: Life-Threatening
• Grade 5: Fatal

A summary of the late skin toxicities experienced by participants. The number of participants effected is shown for each toxicity experienced. Skin toxicities were assessed using Common Terminology Criteria for Adverse Events (CTCAE 4).

To evaluate cosmetic outcome and patient satisfaction with cosmetic outcome, see Secondary Outcome #7 for cosmetic outcomes.

Combined summary of the acute (within 3 months of completing treatment) and late (3 months to 5 years after completion of treatment) toxicities experienced by participants thought to be related to breast reconstruction surgery following proton radiation treatment. Toxicities are assessed using Common Terminology Criteria for Adverse Events (CTCAE 4).

The number of participants that needed unplanned additional surgery for breast reconstruction post-RT.

The number of participant that had early signs of cardiac effects from radiation therapy as assessed using a Strain Echo-cardiogram. The data from the Echo-cardiogram was evaluated for signs of negative impacts to cardiac function as determined by the treating physician. Parameters considered in the evaluation of the echo-cardiogram by the physician included myocardial velocity, strain, strain rate, and torsion. Blood-based cardiac bio-markers pro-BNP and ultra-sensitive troponin-I were also assessed. Either a clinically meaningful change in the strain echo-cardiogram parameters or clinically meaningful elevation of the bio-markers was sufficient to be considered to have early signs of cardiac effects.

Progression-free survival is defined as the duration from the start of radiation to the date of objective disease progression or death due to any cause, whichever is earlier. Disease progression is defined as the appearance of one or more new lesions.