Rajiv Sharma, Abstract Co-Author: Nothing to Disclose

Nitika Thawani MD, Abstract Co-Author: Nothing to Disclose

Linda Hong PhD, Abstract Co-Author: Nothing to Disclose

Madhur Kumar Garg MBBS, MD, Abstract Co-Author: Nothing to Disclose

Shalom Kalnicki MD, Abstract Co-Author: Nothing to Disclose

Marnee Spierer MD, Presenter: Nothing to Disclose

After breast conserving surgery, a seroma often forms in the surgical cavity prior to radiation therapy. If not drained, the seroma can significantly affect the natural shape of the breast and the volume of the tumor bed requiring a boost after whole breast irradiation. The objective of this study was to evaluate the change in seroma volume after whole breast irradiation prior to boost planning.

A retrospective review was performed of women receiving breast conserving therapy with evidence of seroma at the time of whole breast irradiation planning. All patients were initially treated with wide local excision for DCIS or Stage I-IIIA breast cancer. CT simulation was performed before whole breast irradiation and prior to the tumor bed boost. All patients received either a hypofractionated or standard fractionation regimen (42.4Gy in 16 fractions or 50.4 Gy in 28 fractions to the whole breast followed by a 4 fraction, 9.6Gy boost or 5 fraction, 10 Gy boost). Seroma volumes were contoured and compared on CT image sets at the time of whole breast simulation and tumor bed boost planning.

21 patients were identified with evidence of seroma on CT treated from April 2006 through March 2007. 19 patients received whole breast irradiation without drainage of the seroma. Mean seroma volume prior to whole breast irradiation and at boost planning was 69.7cm3 (Range 5.78 - 234.2 cm3) and 37.59cm3 (Range 6.4 - 102.6 cm3), respectively. Mean reduction in seroma volume during radiation was 39.08% (SD=25.59). 2 patients had the seroma drained prior to beginning the boost. Mean seroma volume prior to drainage was 144.85 cm3 (Range= 81.6 - 145.2 cm3). Mean seroma volume after drainage was 46.05cm3 (Range= 17.4 - 74.7 cm3). Mean reduction in seroma volume was 71.39% (SD=10.31). Mean number of days between surgery and radiation therapy was 65.86 (SD= 60.16).

The formation of a breast seroma after wide local excision is a significant factor affecting the volume of tumor bed boost in breast conserving therapy. Our review demonstrates that a significant volume of seroma remains after whole breast irradiation, resulting in large boost volumes. While a moderate reduction in volume does occur during whole breast irradiation, drainage of the seroma prior to the tumor bed boost results in the greatest reduction in seroma volume and thereby the volume of boost irradiation. In addition, CT based boost planning allows accurate target delineation given the dynamic nature of a seroma and hence the tumor bed requiring a boost. Fractionation schedule and length of time from surgery did not affect the change in seroma volume.

Sharma, R, Thawani, N, Hong, L, Garg, M, Kalnicki, S, Spierer, M, Change in Seroma Volume during Whole Breast Radiation Therapy.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/6001625.html