Consensus StatementAmerican Brachytherapy Society consensus statement for soft tissue sarcoma brachytherapy
Introduction
Soft-tissue sarcoma (STS) describes a heterogeneous group of malignant entities, consisting of various pathologies, histologic grades, and sites of origin. Treatment historically consisted of radical resections and amputation, which were associated with a significant detriment in structural function and quality of life. This led to a shift in STS treatment paradigms to a multidisciplinary approach using marginal resection and adjuvant radiation, in hopes of maintaining comparable disease control while improving the patient's quality of life [1], [2], [3], [4]. The first randomized trial to show equivalent disease-specific survival between amputation and limb-sparing surgery with adjuvant radiotherapy (RT) was over three decades ago (2). Now, limb-sparing treatment is the current standard of care.
There are selected cases that can be adequately controlled with wide local excision (WLE) alone [5], [6], [7]. In sarcoma patients with a higher risk of recurrence (i.e., size >5 cm, deep, high grade, recurrent, or closely resected margins), the addition of RT can improve local control (LC). In randomized trials, the addition of external beam radiation therapy (EBRT) (8) or brachytherapy (BT) [9], [10], [11] can offer an absolute LC benefit of ∼20–30% in the setting of limb preserving WLE. Radiation can be administered as EBRT alone, BT alone, or as a combination of EBRT with a brachytherapy boost (EBRT-BT). Treatment with EBRT can be administered in either the preoperative or postoperative setting. Initial trials used postoperative EBRT, but preoperative EBRT has become popular after randomized evidence showed similar LC with the potential for improved late complications [8], [12], [13], [14].
Brachytherapy is primarily delivered intraoperatively or postoperatively. During surgical resection, catheters are implanted in the tumor bed, allowing high radiation dose to the surgical bed with a rapid dose drop to the surrounding normal tissue. This rapid fall off in dose is because of the low energy radiation used in BT, with a limited dose penetration that is in proportion to the inverse square law (1/r2) (15). Historically, BT can better spare normal tissue than EBRT, which may translate to a lower rate of complications (i.e., lymphedema, subcutaneous fibrosis, or bone fractures) [8], [11], [16]. Brachytherapy offers a relatively short and convenient adjuvant treatment, delivered in the inpatient or outpatient setting, usually spanning <1–2 weeks in duration. BT alone is useful when avoiding normal tissue radiation is paramount but is limited in its volume coverage. EBRT can deliver dose to a large volume at risk with increased homogeneity than BT but can increase both low and high radiation dose volumes to normal tissue. The combination of EBRT and BT provides microscopic disease coverage over a sizable volume, which BT alone lacks, and provides faster boost delivery to the surgical bed and a steeper dose gradient, which EBRT alone lacks. In this review, we will discuss BT in STS, focusing on treatment considerations, BT procedures, and patient outcome.
Section snippets
Methods and materials
The American Brachytherapy Society (ABS) board of directors appointed a group of physicians with expertise in sarcoma BT to provide a consensus statement. The previous ABS guideline (17) was updated with recent studies on the topic. Literature review was conducted with inclusion of all human clinical studies available in English language evaluating BT and STS. The goal of these guidelines is to provide an adequate description of treatment considerations, procedural instructions, radiation
Patient workup
STS has a relatively low incidence in the United States, with an estimated 11,930 new cases in 2015 (18), which is best served by a multidisciplinary sarcoma team (19). In addition to staging, preoperative workup should be aimed at assessing extent of disease, resectability, neighboring critical structures, and whether a patient can tolerate treatment (i.e., comorbidities, performance status, previous radiation, etc.). During the history and physical examination, it is important to determine
Discussion
Treatment recommendations and guidelines for dose and fractionation as well technical guidelines are summarized on Table 5. Surgery is the primary component of STS treatment. Surgery alone may be adequate for small (<5 cm) low-grade STS with a clear surgical margin (>1 cm), with nomograms available to assess the risk of recurrence with surgery alone (7). For high-grade STS, adjuvant radiation therapy remains the standard of care with randomized data demonstrating an improvement in LC with EBRT
Conclusion
Brachytherapy remains an essential component in the treatment of STS with data supporting the use of adjuvant BT to improve disease control following local excision. The use of BT monotherapy offers a convenient and effective treatment that spares normal tissue, which is ideal for small high-grade disease, re-irradiation, frail and elderly patients, or children. In combination with EBRT, a BT boost offers an LC benefit for patients with higher risk of recurrence (>10 cm, recurrent, or close
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2022, BrachytherapyCitation Excerpt :For monotherapy, HDR brachytherapy dose and fraction regimens include 30-54 Gy (2-4 Gy/fraction delivered twice daily) and when utilizing LDR brachytherapy, a dose of 45-50 Gy (0.45-0.5 Gy/hr) is prescribed (70). If HDR brachytherapy is utilized as a boost with EBRT, a dose of 12-20 Gy (2-4 Gy/fraction delivered twice daily) is delivered while a dose of 15-25 Gy (0.45-0.5 Gy/hr) is used with LDR brachytherapy when delivered with 45-50 Gy of EBRT (70). While HDR and LDR brachytherapy are the most well studies, there is a role for IORT in the management of sarcomas.
American Brachytherapy Society (ABS) consensus statement for soft-tissue sarcoma brachytherapy
2021, BrachytherapyCitation Excerpt :The ABS Board of Directors appointed a group of physicians with expertise in STS BT to provide a consensus statement. The prior ABS guideline was updated with recent studies on the topic (25); additionally, to provide further information and education for clinicians, a step-by-step procedure outline with images was created. An updated literature review that evaluated articles published since the previous guideline was performed to evaluate human clinical studies available in English language evaluating BT and STS, regardless of tumor location (25).
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Co-senior authorship.