Radiation Doses and Fractionation Schedules in Non-low Risk Ductal Carcinoma In Situ (DCIS) of the Breast

Inclusion Criteria:

Patients must fulfill all of the following criteria for admission to study:

• Women ≥ 18 years.
• Histologically proven DCIS of the breast without an invasive component.
• Bilateral mammograms performed within 6 months prior to randomization.
• Clinically node-negative.
• Treated by breast conserving surgery (primary excision or re-excision) with complete microscopic excision and clear radial margins of ≥1 mm* (*Patients with superficial or deep resection margin of <1 mm are eligible if surgery has removed all of the intervening breast tissue from the subcutaneous tissue to the pectoralis fascia).

• Women who are at high risk of local recurrence due to:

  • Age < 50 years; OR

  • Age ≥ 50 years plus at least one of the following:

    • Symptomatic presentation
    • Palpable tumour
    • Multifocal disease
    • Microscopic tumour size ≥ 1.5 cm in maximum dimension
    • Intermediate or high nuclear grade
    • Central necrosis
    • Comedo histology
    • Radial* surgical resection margin < 10 mm. (*Patients with superficial or deep resection margin of < 10 mm are eligible if surgery has not removed all of the intervening breast tissue from the subcutaneous tissue to the pectoralis fascia.)
• Assessed by surgeon and radiation oncologist to be suitable for breast conserving therapy including whole breast RT.
• Ability to tolerate protocol treatment.
• Protocol RT should preferably commence within 8 weeks but must commence no later than 12 weeks from the last surgical procedure.
• ECOG performance status 0, 1 or 2.
• Patient's life expectancy > 5 years.
• Availability for long-term follow-up.
• Written informed consent.

Exclusion Criteria:

Patients who fulfill any of the following criteria are not eligible for admission to study:

• Multicentric disease or extensive microcalcifications that could not be completely excised by breast conserving surgery with radial margins of ≥1 mm*.

  *Patients with superficial and/or deep margin of <1 mm are eligible if surgery has removed all of the intervening breast tissue from the subcutaneous tissue to the pectoralis fascia.

• Presence of tumour cells in lymph nodes detected using H&E or immunohistochemical examination (if lymph node biopsy or dissection has been performed).
• Locally recurrent breast cancer.

• Previous DCIS or invasive cancer of the contralateral breast.

  • Bilateral DCIS of the breasts
  • Synchronous invasive carcinoma of the contralateral breast

• Other concurrent or previous malignancies except:

  • Non-melanomatous skin cancer;
  • Carcinoma in situ of the cervix or endometrium; and
  • Invasive carcinoma of the cervix, endometrium, colon, thyroid and melanoma treated at least five years prior to study admission without disease recurrence.
• Serious non-malignant disease that precludes definitive surgical or radiation treatment (e.g., scleroderma, systemic lupus erythematosus, cardiovascular/pulmonary/renal disease).
• ECOG performance status ≥ 3.
• Women who are pregnant or lactating.