Clinical Investigation
Postoperative Seroma Formation After Intraoperative Radiotherapy Using Low-Kilovoltage X-Rays Given During Breast-Conserving Surgery

https://doi.org/10.1016/j.ijrobp.2009.06.008Get rights and content

Purpose

To determine the frequency and volume of seroma after breast-conserving surgery (BCS) with or without intraoperative radiotherapy (IORT).

Methods and Materials

Seventy-one patients with 73 breast cancers (IORT group) treated with IORT (20 Gy Intrabeam) as a boost during BCS were compared with 86 patients with 88 breast tumors (NO-IORT group) treated without IORT. Clinical examination and measurement of seroma volume on treatment-planning CT (CT-seroma) was done at median interval of 35 days after BCS.

Results

Seroma were found on palpation in 37 patients (23%) and on CT in 105 patients (65%; median volume, 26.3 mL). Interval between BCS and CT was significantly shorter in patients with palpable seroma (median, 33 days) or CT-seroma (33 days) compared with those with no palpable seroma (36.5 days; p = 0.027) or CT-seroma (52 days, p < 0.001). The rate of palpable seroma was not different (IORT n = 17, 23%; NO-IORT n = 20, 23%; p = 0.933), whereas fewer patients required puncture in the IORT group [3 (4%) vs. 10 (11%)]. In contrast, more patients showed CT-seroma after IORT (IORT n = 59, 81%; NO-IORT n = 46, 52%; p < 0.001). The interval between BCS and CT was significantly shorter in patients with IORT as compared with the NO-IORT patients (median, 33 days vs. 41.5 days; p = 0.036).

Conclusion

Intraoperative radiotherapy with low-kilovoltage X-rays during BCS is not associated with an increased rate of palpable seroma or seroma requiring treatment. The rate of seroma formation on CT was higher after IORT compared with the NO-IORT group, which might be because of the shorter interval between BCS and CT.

Introduction

Intraoperative radiotherapy (IORT) of the tumor bed in breast cancer patients treated with breast-conserving surgery (BCS) is increasingly used, using different devices (electrons, photons, or low-kilovoltage X-rays) and different concepts. There is some information regarding acute toxicity and cosmetic outcome of patients treated with low-kilovoltage X-rays (Intrabeam; Carl Zeiss, Oberkochen, Germany) as a boost 1, 2. Although our initial report (1) showed no significant increase of wound-healing problems in patients treated with IORT, we have reported on a qualitative basis that IORT patients more often show postoperative seroma in the treatment-planning CT compared with patients without IORT. The accumulation of breast seroma after BCS is estimated to occur in 9–15% of patients (3). Often a seroma is palpable and can be visualized during external-beam radiotherapy (EBRT) planning and might influence the shape and the volume of the breast, but is not clinically relevant. Only a small portion of patients show clinically significant seroma. The present retrospective analysis was performed to quantitatively evaluate the frequency and volume of both seroma formation (clinically nonrelevant and clinically relevant) after BCS with or without IORT and to identify influencing factors.

Section snippets

Methods and Materials

Seventy-three breast cancers in 71 patients (IORT group) treated consecutively at the Department of Radiation Oncology, University Mannheim Medical Center (Mannheim, Germany) between 2005 and 2007 with BCS and IORT (20 Gy 50-kV X-rays prescribed at the applicator surface; Intrabeam) as previously reported 4, 5 for tumor bed boost irradiation were included in this analysis. Eighty-eight breast tumors in 86 patients treated in our institution during the same interval with BCS without IORT

Patient characteristics

Both patient groups were equally distributed with respect to patient age, height, weight, tumor size, and tumor localization (Table 2). There was a difference with regard to a larger breast volume for the IORT patients (median breast volume, 1263.9 mL for the IORT group vs. 1088.6 mL for the NO-IORT group; p = 0.004). The BMI was significantly higher in the IORT group compared with the NO-IORT group (median, 27.3 kg/m2 vs. 24.9 kg/m2, respectively; p = 0.025), and the time interval between BCS

Discussion

Postoperative seroma is the most frequent complication of breast cancer surgery. The reported rates for postoperative seroma after wide local excision vary today between 9.2% (4) and 19.2% (6). These results usually relate to a combined assessment including clinical examination and mammogram/ultrasound and are reported in most studies anytime at one time point, usually several weeks after BCS. Especially in patients with larger breast volumes, often a seroma formation can be described on the

Conclusion

The rate of clinically palpable seroma or seroma requiring puncture after BCS with IORT was not increased as compared with BCS alone, whereas the rate of CT-seroma was considerably higher in the IORT group. This finding might at least in part be due to a significantly shorter interval between surgery and planning CT in the IORT group.

References (21)

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    According to Coles et al, where seroma formation on 30 patients was judged by 2 clinical oncology consultants, 8/30 patients had “highly visible” seroma formation, 10/30 had “visible” seroma formation, 6/30 had “subtle” seroma formation, and 6/30 had seroma formation that was “not visible” on CT after surgical closure of the breast after BCS.4 In another study, researchers found that seroma formation could be observed on CT for 65% of patients, with a median of 35 days between BCS and CT.10 Seroma formation is variable and unreliable when delineating the tumor cavity to plan clinical target volume (CTV) for radiation therapy, which includes the gross tumor volume plus an additional margin. Without any kind of fiducial markers, the tumor bed can be underdosed and healthy tissue can be unnecessarily dosed as a result of an inaccurately determined CTV.

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    Other authors confirmed this good tolerance, with a rate of grade 3 postoperative complications <5%26,27. In some series, the incidence of seroma was increased28. In our series, we observed wound healing >15 days among 11% of our patients, which was comparable to the rate observed after partial mastectomy without IORT.

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    Therefore, the presence of a seroma at the time of radiotherapy planning was used as a surrogate for standard wound closure over the tumour bed. Clinical assessment of breast seroma is subjective and can be difficult to appreciate in patients with high body mass index (BMI).19 Radiotherapy planning CT scans were used in this study to define the tumour bed seroma, as this method is more objective and independent of BMI.

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    Because tIORT potentially offers more conformal radiation delivery than external beam radiation therapy, it may have less adverse impact on the cosmetic result than external beam boost (11). However, seroma formation was reported to be common after tIORT and might be associated with an adverse cosmetic outcome (12-14). The aims of this study were to evaluate cosmetic outcome and its association with seroma formation and aspiration after BCS with tIORT boost followed by WBRT.

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Conflict of interest: none.

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