A Randomized Trial of Five Fraction Partial Breast Irradiation (RAPID2)

Inclusion Criteria:

For inclusion in this study, patients must fulfill all of the following criteria:

1. Female with a new histological diagnosis of invasive carcinoma of the breast with noevidence of metastatic disease (see AJCC TNM Cancer Staging, Appendix II).

2. Treated by BCS with microscopically clear resection margins >= 1mm for invasive andnon-invasive disease or no residual disease on re-excision.

3. Negative axillary node involvement as determined by either sentinel lymph nodebiopsy or axillary node dissection or clinical assessment with a negative axillaryultrasound and/or biopsy, for women with unifocal tumours <= 2cm, histologic grade 1or 2, ER or PR+ and HER2-ve that are being planned for endocrine therapy

Exclusion Criteria:

Patients who satisfy any of the following exclusion criteria are NOT eligible for this study:

1. Age less than 50 years.

2. Known to be BRCA 1 and/or BRCA 2 positive.

3. Tumour size >3cm in greatest diameter on pathological examination.

4. Evidence of extensive intraductal component (EIC) (defined as an invasive tumourwith a ductal carcinoma in situ (DCIS) component comprising at least 25% andextending beyond the invasive component to surrounding normal breast tissue) withthe following exception: smaller tumours with EIC where the combined size (of theinvasive and DCIS components) are <= 3cm remain eligible

5. Evidence of a DCIS component > 3cm

6. Lobular carcinoma only.

7. More than one primary tumour in different quadrants of the same breast (patientswith multifocal breast cancer are eligible).

8. Synchronous or previous contralateral breast cancer (patients with contralateralDCIS or LCIS are eligible).

9. History of non-breast malignancy within the last 5 years other than treatednon-melanoma skin cancer or treated in-situ carcinoma.

10. Known pregnancy or currently lactating.

11. Inability to localize tumour bed on CT planning (no evidence of surgical clips orseroma).

12. Inability to plan the patient for the experimental technique.