Breast/Soft TissueManagement of ductal carcinoma in situ with accelerated partial breast irradiation brachytherapy: Implications for guideline expansion
Introduction
Breast conservation surgery has been offered to patients since the 1950s (1), with studies showing that breast conservation therapy with whole breast irradiation (WBI) has similar outcomes to modified radical mastectomy (2, 3). However, as most ipsilateral breast tumor recurrences (IBTRs) occur near the original tumor site, radiation treatment of the whole breast may be excessive in some situations (4, 5). Accelerated partial breast irradiation (APBI) offers a promising alternative to WBI in this regard, as the treatment is directed to the area with highest risk of recurrence, the surgical cavity, as opposed to the whole breast. APBI provides a shorter radiation treatment at a higher dose per fraction, theoretically providing equivalent local control while reducing toxicity and improving cosmetic outcomes (6, 7). Early studies evaluating the efficacy of APBI found high recurrence rates, emphasizing the importance of careful patient selection (8, 9). The evolution of APBI has resulted in multiple modern APBI techniques, including both external beam and brachytherapy-based delivery methods. The advent of the intracavitary brachytherapy technique helped to provide a more accessible approach to APBI administration (10), whereas alternative models aim to improve conformity of radiation via multicatheter designs (11, 12). Brachytherapy APBI to a dose of 34 Gy in 10 fractions, delivered twice per day over 1 week, has been shown to be efficacious (13).
The role of APBI in the treatment of patients with ductal carcinoma in situ (DCIS) is controversial, as prior studies have demonstrated a significant number of DCIS tumors are multifocal with a higher risk of local recurrence (14, 15). Recently updated American Society of Radiation Oncology (ASTRO) guidelines have now expanded their suitable criteria to include low-risk patients with DCIS (screen-detected lesions, low to intermediate grade, tumor size ≤ 2.5 cm, margins negative by ≥ 3 mm) per RTOG 9804 criteria (16), as ‘suitable’, if other suitability criteria are met (i.e., age ≥ 50 years of age) (17). Patients with DCIS who do not meet suitability criteria because of risk factors like young age, close margins, or high grade are deemed ‘cautionary’. The American Brachytherapy Society (ABS) deems patients with DCIS acceptable for APBI if they are ≥ 45 years old with tumor size ≤ 3 cm, surgical margins ≥ 2 mm, lymph node negative, and without lymphovascular space invasion, regardless of estrogen receptor (ER) status (Table 1) (18). The European Society for Radiotherapy and Oncology (GEC-ESTRO) guidelines exclude patients with DCIS from the low-risk group (19). These patients are considered intermediate risk if other criteria are met, such as age ≥ 40 years, tumor size ≤ 3 cm, and margins negative, regardless of ER status.
Given these important differences among the APBI criteria for treatment of patients with DCIS and the importance of careful patient selection, the purpose of this study was to evaluate these guidelines using a single-institutional experience with APBI intracavitary brachytherapy in treating DCIS.
Section snippets
Study design and patient selection
This is a retrospective review of 169 consecutive clinically node-negative patients with pathology-confirmed breast DCIS treated with lumpectomy followed by APBI intracavitary brachytherapy to 34.0 Gy in 10 fractions given twice daily at least 6 h apart from 2003 to 2018. The study was approved by the institutional review board. Each case was classified by the suitability criteria of the ABS, ASTRO, and GEC-ESTRO (Table 1). Of note, the lack of nodal assessment (pNx) was not used as a
Patient characteristics
The median age at treatment was 66 years, and the vast majority of patients were postmenopausal (98%) (Table 2). The majority of cases were ER positive (89%), Grade 1–2 (69%), and achieved surgical margins of at least 2 mm (64%). Most patients were prescribed and started hormone therapy (72%), and of the 77 patients with adequate followup documentation, 20 (26%) had confirmed adherence for at least 5 years.
Of the 130 cases with adequate clinicopathologic details, 97 (74.6%) were deemed suitable
Discussion
APBI provides durable local control with minimal toxicity and good cosmetic outcomes for select patients with breast cancer (20). However, little is known about the role of APBI for patients with DCIS, and the original ASTRO consensus statement listed DCIS as a cautionary feature (21). The ECOG E5194 (22) clinical trial demonstrated a minimal risk of ipsilateral breast event (IBE) after lumpectomy alone for select low-risk patients with DCIS (low-intermediate grade, tumor size ≤2.5 cm, margins
Conclusions
These results demonstrate that intracavitary brachytherapy APBI is an effective treatment option for patients with DCIS, providing adequate local control with minimal toxicity. Although limited by short-term followup, these results do suggest that expansion of the current APBI suitability criteria for patients with DCIS should be considered.
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Cited by (1)
DCIS: When is accelerated partial breast irradiation an option? A meta-analysis on outcomes and eligibility
2023, American Journal of Surgery
Funding: This work was supported by the Morton Plant Mease Foundation.
Disclosures: The authors report no proprietary or commercial interest in any product mentioned or concept discussed in this article.