A Phase II Study of Real-Time MRI-Guided 3-Fraction Accelerated Partial Breast Irradiation in Early Breast Cancer (MAPBI)
This trial will investigate a novel 3-fraction radiation regimen for participants undergoing breast-conserving therapy (BCT) for early breast cancer that will: 1) significantly reduce the duration of treatment and can be completed in one-week (5 working days) and 2) MRI-guided radiotherapy (MRIdian) would limit the volume of normal tissue radiated and therefore resultant toxicity. The hypothesis is that 3-fraction radiation therapy can be delivered safely without compromising the therapeutic ratio. Participants can expect to be on study for follow up up to 5 years.
∙ For all participants
• Participants should have no contraindications to undergo MRI scan as part of radiotherapy planning and treatment.
• Lumpectomy cavity must be clearly visible on CT and MRI scan at radiotherapy simulation.
• Pregnancy test negative in women of child bearing potential (WOCBP).
• The participant must consent to be in the study and must have signed an approved consent form conforming with institutional guidelines.
• Participants with a history of non-breast malignancies are eligible if they have been disease-free for 5 or more years prior and are deemed by their physician to be at low risk for recurrence. Participants with the following cancers are eligible if diagnosed and treated within the past 5 years: carcinoma in situ of the cervix, carcinoma in situ of the colon, melanoma in situ, and basal cell and squamous cell carcinoma of the skin.
∙ For participants with Invasive Carcinoma
• Suitable:
‣ Age: \>=50 years
• Margins: Negative by at least 2 mm
∙ T Stage: Tis or T1
• Cautionary:
‣ Age: 40-49 years
• Margins: Negative by at least 2 mm
∙ T Stage: Tis or T1 OR
⁃ Age: \>=50 years IF participant has at least 1 of the pathologic factors below and does not have any unsuitable factors (below)
• Pathologic Factors:
‣ Size 2.1-3.0 cm (size of the invasive component)
⁃ T2
⁃ Close margins (\<2 mm)
⁃ Limited/focal Lymphovascular Space Invasion (LVSI)
⁃ ER (-)
⁃ Clinically unifocal with total size 2.1-3.0 cm (Microscopic multifocality allowed, provided the lesion is clinically unifocal (a single discrete lesion by physical examination and ultrasonography/mammography) and the total lesion size (including foci of multifocality and intervening normal breast parenchyma) falls between 2.1 and 3.0 cm).
⁃ Invasive lobular histology
⁃ Extensive Intraductal Component (EIC) \<=3 cm
∙ For participants with DCIS
• Suitable Criteria, DCIS allowed if all of the following are met:
‣ Screen-detected
⁃ Low to intermediate nuclear grade
⁃ Size \<=2.5 cm
⁃ Resected with margins negative at \>=3mm OR
• Cautionary Criteria:
‣ Pure DCIS \<=3 cm if suitable criteria not fully met