Radiation Therapy in Women With Low Risk Early-Stage Breast Cancer Who Have Undergone Breast Conservation Surgery

RATIONALE: Radiation therapy uses high-energy x-rays to kill tumor cells. Giving radiation therapy after surgery may kill any tumor cells that remain after surgery. It is not yet known whether intensity-modulated radiation therapy is more effective than standard radiation therapy in treating patients with early-stage breast cancer. PURPOSE: This randomized phase III trial is comparing radiation therapy regimens in treating women with early-stage breast cancer who have undergone breast-conservation surgery.

Sex

Female

Minimum age

50 Years

DISEASE CHARACTERISTICS:

* Diagnosis of low-risk early stage breast cancer, meeting the following criteria:

  * Invasive adenocarcinoma

    * No invasive carcinoma of classical lobular type
    * lympho-vascular invasion present or absent
  * Tumor size pathologically determined to be ≤ 3.0 cm in diameter (pT1-2) (\< 3.1 cm maximum microscopic diameter of invasive component)
  * Unifocal disease
  * Grade I, II, or III disease
  * Axillary lymph nodes negative or 1-3 nodes positive (pN0 or pN+(1-3))
* Must have undergone breast conservation surgery with or without adjuvant systemic therapy

  * Minimum microscopic margin of non-cancerous tissue ≥ 2 mm (excluding deep margin if this is at deep fascia)
* At low risk of local recurrence after radiotherapy (\< 1% annual risk local recurrence)
* No prior mastectomy
* No blood-borne metastases

PATIENT CHARACTERISTICS:

* No prior malignancy except nonmelanoma skin cancer

PRIOR CONCURRENT THERAPY:

* See Disease Characteristics
* No prior endocrine therapy or chemotherapy

  * Neoadjuvant endocrine therapy allowed provided the tumour is \< 3.0 cm and all other inclusion criteria are met
  * No primary endocrine therapy as a replacement for surgery
* No concurrent chemoradiotherapy

• BACKGROUNDColes CE, Griffin CL, Kirby AM, Titley J, Agrawal RK, Alhasso A, Bhattacharya IS, Brunt AM, Ciurlionis L, Chan C, Donovan EM, Emson MA, Harnett AN, Haviland JS, Hopwood P, Jefford ML, Kaggwa R, Sawyer EJ, Syndikus I, Tsang YM, Wheatley DA, Wilcox M, Yarnold JR, Bliss JM; IMPORT Trialists. Partial-breast radiotherapy after breast conservation surgery for patients with early breast cancer (UK IMPORT LOW trial): 5-year results from a multicentre, randomised, controlled, phase 3, non-inferiority trial. Lancet. 2017 Sep 9;390(10099):1048-1060. doi: 10.1016/S0140-6736(17)31145-5. Epub 2017 Aug 2. PMID 28779963
• BACKGROUNDBhattacharya IS, Haviland JS, Kirby AM, Kirwan CC, Hopwood P, Yarnold JR, Bliss JM, Coles CE; IMPORT Trialists. Patient-Reported Outcomes Over 5 Years After Whole- or Partial-Breast Radiotherapy: Longitudinal Analysis of the IMPORT LOW (CRUK/06/003) Phase III Randomized Controlled Trial. J Clin Oncol. 2019 Feb 1;37(4):305-317. doi: 10.1200/JCO.18.00982. Epub 2018 Dec 11. PMID 30532984
• BACKGROUNDKirby AM, Bhattacharya IS, Wilcox M, Haviland JS. The IMPORT LOW Trial: Collaborative Research Accelerates Practice Change in Breast Radiotherapy. Clin Oncol (R Coll Radiol). 2019 Jan;31(1):5-8. doi: 10.1016/j.clon.2018.08.007. Epub 2018 Sep 17. No abstract available. PMID 30236641
• BACKGROUNDColes C, Yarnold J; IMPORT Trials Management Group. The IMPORT trials are launched (September 2006). Clin Oncol (R Coll Radiol). 2006 Oct;18(8):587-90. doi: 10.1016/j.clon.2006.07.010. No abstract available. PMID 17051947