Postoperative seroma formation after intraoperative radiotherapy using low-kilovoltage X-rays given during...

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

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.

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).

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.