The Dynamic Tumor Bed: Volumetric Changes in the Lumpectomy Cavity During Breast-Conserving Therapy

The purpose of this study was to evaluate the rate of change (RoC) in the size of the lumpectomy cavity (LC) before and during breast radiotherapy (RT) using cone‐beam computed tomography (CBCT), relative to the initial LC volume at CT simulation (CTVLC) and timing from surgery. A prospective institutional review board‐approved study included 26 patients undergoing breast RT: 20 whole breast irradiation (WBI) patients and six partial breast irradiation (PBI) patients, with surgical clips outlining the LC. The patients underwent CT simulation (CTsim) followed by five CBCTs during RT, once daily for PBI and once weekly for WBI. The distance between surgical clips and their centroid (D) acted as a surrogate for LC size. The RoC of the LC size, defined as the percentage change of D between two scans divided by the time interval in days between the scans, was calculated before (CTsim to CBCT1) and during RT (CBCT1 to CBCT5). The mean RoC of D for all patients before starting RT was −0.25%/day (range, −1.3 to 1.4) and for WBI patients during RT was −0.15%/day (range, −0.45 to 0.40). Stratified by median CTVLC, the RoC before RT for large CTVLC group (≥25.7cc) was 15 times higher (−0.47%/day) than for small CTVLC group (<25.7 cc) (−0.03%/day), p=0.06. For patients undergoing CTsim < 42 days from surgery, the RoC before RT was −0.43%/day compared to −0.07%/day for patients undergoing CTsim≥42 days from surgery, p=0.12. For breast cancer RT, the rate of change of the LC is affected by the initial cavity size and the timing from surgery. Resimulation closer to the time of boost treatment should be considered in patients who are initially simulated within six weeks of surgery and/or with large CTVLC.PACS number: 87.55.de

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“…Prendergast et al ( 13 ) studied LC volume changes both before and after commencing RT in 36 patients undergoing WBI (

normaln = 30

) and PBI (

normaln = 6

). CT scans were performed shortly after surgery, at

{CT}_{sim}

and before the start of the treatment boost.…”

Section: Discussionmentioning

confidence: 99%

“…The results for initial

{CTV}_{LC}

and change in

{CTV}_{LC}

were mixed, with some studies reporting larger volume reduction over time with a larger initial

{CTV}_{LC}

, ( 12 , 14 , 16 , 17 ) while others reported no correlation. ( 8 , 9 , 13 ) …”

Section: Discussionmentioning

confidence: 99%

Cone‐beam computed tomography image guided therapy to evaluate lumpectomy cavity variation before and during breast radiotherapy

Truong

Hirsch

Kovalchuk

et al. 2013

J Applied Clin Med Phys

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“…Few studies have quantified tumor bed volume changes during the course of treatment (Prendergast et al, 2009). Redefining the tumor bed right before the boost treatment will give a better assessment for the boost volume, and the ultrasound image provides a convenient method for this without giving extra dose to the patient.…”

Section: Inter-fractional Changes In Tumor Bed Volume and Position Wimentioning

confidence: 99%

Clinical Application of Ultrasound Imaging in Radiation Therapy

Kim¹,

Brandner²,

Huq³

et al. 2011

Ultrasound Imaging - Medical Applications

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“…After superficial closure of the excision cavity, the tumor bed often appears as a seroma [9,10], which makes target definition more clear and consistent. Seroma volume (SV) is well-known to typically shrink with time [11][12][13][14][15][16][17]. Therefore, an ideal target volume should differ in each PBI fraction.…”

Section: Introductionmentioning

confidence: 99%

Seroma Change during Magnetic Resonance Imaging-Guided Partial Breast Irradiation and Its Clinical Implications

Jeon

Shin

Park

et al. 2017

International Journal of Radiation Oncology*Biology*Physics

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Background: To investigate the patterns of post-lumpectomy seroma volume (SV) change and related clinical factors to determine the benefits of adaptive planning in magnetic resonance imaging (MRI)-guided partial breast irradiation (PBI). Methods: MRI data obtained from 37 women with early breast cancer acquired at simulation and at the 1st, 6th, and 10th fractions were analyzed. The planning target volume (PTV) was defined as unequal margins of 10-15 mm added according to the directional surgical margin status of each seroma. Treatment was performed using a 0.35 T MRI-guided radiotherapy system. Univariate analysis was performed to assess the correlations between SV change rate and clinical factors. Seroma and PTV for adaptive planning were based on the images obtained at the 6th fraction.

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The Dynamic Tumor Bed: Volumetric Changes in the Lumpectomy Cavity During Breast-Conserving Therapy

Cited by 53 publications

References 28 publications

Cone‐beam computed tomography image guided therapy to evaluate lumpectomy cavity variation before and during breast radiotherapy

Cone‐beam computed tomography image guided therapy to evaluate lumpectomy cavity variation before and during breast radiotherapy

Clinical Application of Ultrasound Imaging in Radiation Therapy

Seroma Change during Magnetic Resonance Imaging-Guided Partial Breast Irradiation and Its Clinical Implications

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