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Accelerated Partial Breast Irradiation for Breast Cancer

Key Questions Draft

Open for comment through May 14, 2021

Background

In 2017, female breast cancer was the form of cancer with the highest incidence of new cases and the second highest incidence of death in the United States.1 The most common treatment for breast cancer is breast-conserving surgery with adjuvant radiation therapy.2 The goal of radiation therapy in breast cancer treatment is to eradicate subclinical disease following the surgical removal of tumors.3

Radiation therapy administered in patients with early stage breast cancer reduces tumor recurrence and increases survival.4,5 Variations in technique from standard whole breast radiation therapy aim to reduce treatment time, facilitate convenience, and/or limit radiation exposure to normal tissue. Accelerated PBI is one such technique, and has been shown to accomplish some of these aims.3 As part of PBI, radiation is delivered to tissue only immediately adjacent to the site of the removed tumor, and is convenient in that it can be completed in five treatment days.6 Methods of PBI include multicatheter brachytherapy, intracavitary balloon brachytherapy, intraoperative radiation therapy, and external beam conformal therapy.3

Contemporary studies of PBI continue to demonstrate significant variation in care. Clinicians face difficult patient presentations where numerous factors related to patient-specific values and expectations, and varied imaging and clinical features that must be considered.7,8 A new systematic review would inform an update to the current ASTRO 2016 guidelines that would include information that could provide indications for more tailored treatment based on patient characteristics and clinical features.

Draft Key Questions

  1. In adult women with early stage breast cancer, what is the comparative effectiveness of whole breast irradiation (WBI) compared to partial breast irradiation (PBI)? Which clinical-pathologic characteristics are associated with effectiveness for PBI compared to WBI?
  2. In adult women with early stage breast cancer receiving PBI, what is the comparative effectiveness of PBI techniques (e.g., multicatheter interstitial brachytherapy, single-entry catheter brachytherapy [including devices such as MammoSite, Contura, and SAVI], 3-dimensional conformal external beam radiation therapy, intensity modulated radiation therapy, and proton radiation therapy, intra-operative radiotherapy) on ipsilateral breast cancer outcomes, harms, and quality of life?
  3. In adult women with early stage breast cancer, what is the comparative effectiveness of different dose-fractionation schemes, target volumes, motion management, treatment techniques and optimal planning parameters for accelerated PBI compared to WBI on breast cancer outcomes, harms, and quality of life?
  4. In adult women with early stage breast cancer, what is the comparative effectiveness of preoperative compared to postoperative imaging assessment for patients who meet clinical-pathologic criteria for treatment with PBI?
  5. In adult women with early stage breast cancer, what is the comparative effectiveness in terms of cosmesis and treatment toxicities between PBI and WBI?

Draft Analytic Framework

Figure 1. Draft analytic framework for Key Questions 1, 3 & 5

Figure 1: This figure depicts key questions 1, 3, and 5 within the context of the PICO Framework described in Table 1. In general, the figure illustrates how interventions such as partial breast irradiation (which can be customized by dose fractionation, target volume, motion management, etc.) and whole breast irradiation may result in health outcomes such as breast cancer recurrence, survival, cancer-free survival, quality of life and cosmesis. Also, adverse events may occur after the intervention is received.

 

Figure 2. Draft analytic framework for Key Question 2

Figure 2: This figure depicts key question 2 within the context of the PICO Framework described in Table 1. In general, the figure illustrates how different partial breast irradiation techniques which include multicatheter interstitial brachytherapy, single-entry catheter brachytherapy, 3-D conformal external beam radiation therapy, intensity modulated radiation therapy, proton radiation therapy, and intraoperative radiation therapy may result in health outcomes such as breast cancer recurrence and quality of life. Also, adverse events may occur after the intervention is received.

 

Figure 3. Draft analytic framework for Key Question 4

Figure 3: This figure depicts key question 4 within the context of the PICO Framework described in Table 1. In general, the figure illustrates how interventions such as partial breast irradiation with post-operative imaging and partial breast irradiation with pre-operative imaging may result in health outcomes such as cavity visualization scores. Also, adverse events may occur after the intervention is received.

Table 1. Key Questions and PICO Framework

  KQ1: PBI vs. WBI KQ2: PBI techniques KQ3: Dose fractionation schemes, target volumes, etc. in PBI vs. WBI KQ4: Pre- vs. post-operative imaging assessment KQ5: Cosmesis and treatment toxicity in PBI vs. WBI
Population

Adult women with early stage breast cancer (invasive or non-invasive carcinoma less than or equal to 3 cm and N0/1).

Consider patient characteristics such as age, breast cancer type, breast cancer stage, tumor size, tumor margin status, estrogen receptor status, etc.

Adult women with early stage breast cancer (invasive or noninvasive carcinoma less than or equal to 3 cm and N0/1) receiving PBI. Adult women with early stage breast cancer (invasive or non-invasive carcinoma less than or equal to 3 cm and N0/1). Adult women with early stage breast cancer (invasive or non-invasive carcinoma less than or equal to 3 cm and N0/1) who meet clinic-pathologic criteria for treatment with PBI. Adult women with early stage breast cancer (invasive or non-invasive carcinoma less than or equal to 3 cm and N0/1)
Interventions PBI PBI techniques (e.g., multicatheter interstitial brachytherapy, single-entry catheter brachy-therapy [including devices such as MammoSite, Contura, and SAVI], 3-dimensional conformal external beam radiation therapy, intensity modulated radiation therapy, and proton radiation therapy, IORT). Dose-fractionation schemes, target volumes, motion management, treatment techniques, and optimal planning parameters (i.e., the diameter of the inflated balloon, the planning target volume, and the dose distribution) for PBI. Post-operative imaging assessment for PBI PBI
Comparators WBI PBI techniques WBI Pre-operative imaging assessment for PBI. WBI
Outcomes Breast cancer recurrence, survival, cancer-free survival, quality of life. Breast cancer recurrence; short and long-term harms (e.g., Radiation Therapy Oncology Group scores and Late Effects Normal Tissue Task Force—Subjective, Objective, Management, Analytic scales), quality of life. Breast cancer recurrence, short- and long-term harms (e.g., Radiation Therapy Oncology Group scores and Late Effects Normal Tissue Task Force—Subjective, Objective, Management, Analytic scales), quality of life. Cavity visualization score, harms. Cosmesis, treatment toxicities, other short- and long-term harms (e.g., Radiation Therapy Oncology Group scores and Late Effects Normal Tissue Task Force—Subjective, Objective, Management, Analytic scales)

Abbreviations: KQ=Key Questions; PICO=Populations, Intervention, Comparators, Outcomes; PBI=partial breast irradiation; WBI=whole breast irradiation; IORT=intraoperative radiation therapy

 

References

  1. United States Cancer Statisitics: Data Visualizations. Centers for Disease Control and Prevention.
  2. Miller KD, Nogueira L, Mariotto AB, et al. Cancer treatment and survivorship statistics, 2019. CA: A Cancer Journal for Clinicians. 2019;69(5):363-85. doi: 10.3322/caac.21565.
  3. Yang TJ, Ho AY. Radiation therapy in the management of breast cancer. Surg Clin North Am. 2013 Apr;93(2):455-71. doi: 10.1016/j.suc.2013.01.002. PMID: 23464696. 
  4. Clarke M, Collins R, Darby S, et al. Effects of radiotherapy and of differences in the extent of surgery for early breast cancer on local recurrence and 15-year survival: an overview of the randomised trials. Lancet. 2005 Dec 17;366(9503):2087-106. doi: 10.1016/s0140-6736(05)67887-7. PMID: 16360786.
  5. Smith BD, Bellon JR, Blitzblau R, et al. Radiation therapy for the whole breast: Executive summary of an American Society for Radiation Oncology (ASTRO) evidence-based guideline. Pract Radiat Oncol. 2018 May-Jun;8(3):145-52. doi: 10.1016/j.prro.2018.01.012. PMID: 29545124.
  6. Thomas MA, Ochoa LL, Zygmunt TM, et al. Accelerated Partial Breast Irradiation: A Safe, Effective, and Convenient Early Breast Cancer Treatment Option. Missouri medicine. 2015 Sep-Oct;112(5):379-84. PMID: 26606820. 
  7. Feinstein AJ, Soulos PR, Long JB, et al. Variation in receipt of radiation therapy after breast conserving surgery: assessing the impact of physicians and geographic regions. Medical care. 2013;51(4):330-8. doi: 10.1097/MLR.0b013e31827631b0. PMID: 23151590.
  8. Correa C, Harris EE, Leonardi MC, et al. Accelerated Partial Breast Irradiation: Executive summary for the update of an ASTRO Evidence-Based Consensus Statement. Pract Radiat Oncol. 2017 Mar-Apr;7(2):73-9. doi: 10.1016/j.prro.2016.09.007. PMID: 27866865.